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BACKGROUND: Early cardiac allograft vasculopathy (CAV) prognostication is needed to improve long-term outcomes after heart transplantation. We characterized first year posttransplant coronary anatomic-physiologic alterations to determine predictors of early CAV progression. METHODS: Heart transplant recipients at 2 institutions (enrolled January 2018 to March 2021) underwent prospective evaluation 3 and 12-month posttransplant with angiography and left anterior descending artery intravascular ultrasound, optical coherence tomography, fractional flow reserve, coronary flow reserve, and index of microcirculatory resistance measurements. CAV progression was assessed by intravascular ultrasound change in percentage intimal volume from baseline to 12-month follow-up. RESULTS: Eighty-two patients (mean age, 51 years; 60% men) completed evaluation at mean 13.8 and 56.3 weeks posttransplant. Donor atherosclerosis (baseline intravascular ultrasound maximal intimal thickness, ≥0.5 mm) was evident in 50%. De novo (follow-up maximal intimal thickness, ≥0.5 mm) and rapidly progressive CAV (maximal intimal thickness, ≥0.5-mm increase from baseline) developed in 24% and 13%, respectively. On optical coherence tomography, baseline to follow-up median intimal volume increased 42% (0.58 mm 3 /mm), percentage intimal volume increased 44% (4.6%), vessel volume decreased 4% (−0.50 mm 3 /mm) and lumen volume decreased 9% (−1.02 mm 3 /mm); P CONCLUSIONS: Fibrotic plaque on optical coherence tomography and index of microcirculatory resistance early posttransplant predict CAV progression in the first year of transplantation. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03217786.

The optimal length of dual antiplatelet therapy (DAPT) after percutaneous coronary intervention (PCI) remains debated. Current guidelines recommend individualized treatment with consideration of risk scores. We sought to evaluate the degree of agreement in treatment recommendations and the ability to predict ischemic and bleeding complications of the PRECISE-DAPT (predicting bleeding complications in patients undergoing stent implantation and subsequent dual antiplatelet therapy) and DAPT scores. Consecutive patients receiving 12 months of DAPT were grouped based on score treatment recommendation at the time of PCI: PRECISE-DAPT prolonged or shortened (PRECISE DAPT25 vs ≥25) and DAPT prolonged or shortened (DAPT ≥2 vs2). One-year ischemic and bleeding outcomes were compared for each group. In 451 patients, the PRECISE-DAPT and DAPT score recommendations were concordant in 56.7% of patients (Cohen's kappa for agreement of k = 0.139, 95% confidence interval 0.065 to 0.212). There was no difference in composite major adverse cardiovascular and cerebrovascular events between patients with high versus low PRECISE-DAPT or DAPT scores. In patients with a high PRECISE-DAPT score versus a low score, there was an increased incidence of 1-year all-cause mortality (2.13% vs 0%, p = 0.04) and an increase in bleeding (Bleeding Academic Research Consortium ≥3a: 17.0% vs 2.8%; p0.001; Bleeding Academic Research Consortium 3b/c and 5: 8.5% vs 1.4%; p = 0.001). There were no differences in rates of mortality or bleeding for patients with high versus low DAPT scores. In conclusion, when applied at the baseline, the PRECISE-DAPT and DAPT scores frequently make discordant DAPT duration recommendations. The PRECISE-DAPT, but not the DAPT score, demonstrated associations with all-cause mortality and bleeding in patients prescribed 12 months of DAPT after PCI.

Background: As a result of the COVID-19 pandemic first wave, reductions in ST-elevation myocardial infarction (STEMI) invasive care, ranging from 23% to 76%, have been reported from various countries. Whether this change had any impact on coronary angiography (CA) volume or on mechanical support device use for STEMI and post-STEMI mechanical complications in Canada is unknown. Methods: We administered a Canada-wide survey to all cardiac catheterization laboratory directors, seeking the volume of CA use for STEMI performed during the period from March 1 2020 to May 31, 2020 (pandemic period), and during 2 control periods (March 1, 2019 to May 31, 2019 and March 1, 2018 to May 31, 2018). The number of left ventricular support devices used, as well as the number of ventricular septal defects and papillary muscle rupture cases diagnosed, was also recorded. We also assessed whether the number of COVID-19 cases recorded in each province was associated with STEMI-related CA volume. Results: A total of 41 of 42 Canadian catheterization laboratories (98%) provided data. There was a modest but statistically significant 16% reduction (incidence rate ratio [IRR] 0.84; 95% confidence interval 0.80-0.87) in CA for STEMI during the first wave of the pandemic, compared to control periods. IRR was not associated with provincial COVID-19 caseload. We observed a 26% reduction (IRR 0.74; 95% confidence interval 0.61-0.89) in the use of intra-aortic balloon pump use for STEMI. Use of an Impella pump and mechanical complications from STEMI were exceedingly rare. Conclusions: We observed a modest 16% decrease in use of CA for STEMI during the pandemic first wave in Canada, lower than the level reported in other countries. Provincial COVID-19 caseload did not influence this reduction. Résumé: Introduction: Après la première vague de la pandémie de COVID-19, de nombreux pays ont déclaré une réduction de 23 % à 76 % des soins invasifs de l'infarctus du myocarde avec élévation du segment ST (STEMI). On ignore si ce changement a entraîné des répercussions sur le volume d'angiographies coronariennes (AC) ou sur l'utilisation des dispositifs d'assistance mécanique lors de STEMI et des complications mécaniques post-STEMI au Canada. Méthodes: Nous avons réalisé un sondage pancanadien auprès de tous les directeurs de laboratoire de cathétérisme cardiaque pour obtenir le volume d'utilisation des AC lors des STEMI réalisées durant la période du 1er mars 2020 au 31 mai 2020 (période de pandémie) et durant 2 périodes témoins (1er mars 2019 au 31 mai 2019 et 1er mars 2018 au 31 mai 2018). Le nombre de dispositifs d'assistance ventriculaire gauche utilisés et le nombre de cas de communications interventriculaires et de ruptures du muscle papillaire diagnostiqués ont également été enregistrés. Nous avons aussi évalué si le nombre de cas de COVID-19 enregistrés dans chaque province était associé au volume d'AC liées aux STEMI. Résultats: Au total, 41 des 42 laboratoires canadiens de cathétérisme (98 %) ont fourni des données. Lors de la comparaison de la première vague de la pandémie aux périodes témoins, nous avons noté une réduction modeste, mais significative, sur le plan statistique de 16 % (ratio du taux d'incidence [RTI] 0,84; intervalle de confiance à 95 % 0,80-0,87) des AC lors de STEMI. Le RTI n’était pas associé au nombre provincial de cas de COVID-19. Nous avons observé une réduction de 26 % (RTI 0,74; intervalle de confiance à 95 % 0,61-0,89) de l'utilisation de pompes à ballonnet intra-aortique lors de STEMI. L'utilisation d'une pompe Impella et les complications mécaniques après les STEMI étaient extrêmement rares. Conclusions: Nous avons observé une diminution modeste de 16 % de l'utilisation des AC lors de STEMI durant la première vague de la pandémie au Canada, soit une diminution plus faible que ce que les autres pays ont signalé. Le nombre provincial de cas de COVID-19 n'a pas influencé cette réduction.

Background: De-escalation from potent platelet P2Y12 inhibitors to clopidogrel is common. Despite having a clinical rationale, non-bleeding-related de-escalation when a lateral change between potent agents is an option may put patients at increased ischemic risk. We set out to define the scope of P2Y12 inhibitor de-escalation in a large clinical registry and evaluate the potential impact of non-bleeding-related de-escalation on clinical outcomes. Methods: : A retrospective cohort study was performed on consecutive patients in the Cardiovascular Percutaneous Intervention Trial (CAPITAL) registry to identify those who underwent a switch in therapy within 1 year of percutaneous coronary intervention. The de-escalations were categorized as bleeding-related or non-bleeding-related. The primary outcome was major adverse cardiovascular events, a composite of death, myocardial infarction, and stroke. Secondary outcomes included individual components of major adverse cardiovascular events and a safety endpoint of thrombolysis in myocardial infarction bleeding. Results: Of 1854 patients, 209 (11.3%) underwent de-escalation: 24.9% of cases were bleeding-related, 37.8% were non-bleeding-related, and 37.3% were for unknown reasons. All patients with non-bleeding-related de-escalation were switched from ticagrelor to clopidogrel. The primary outcome occurred in 14 (6.7%) patients, of which 50% underwent non-bleeding-related de-escalation (P = 0.430). Among those with non-bleeding-related de-escalation, 7.6% were hospitalized for myocardial infarction, compared to 1.9% and 3.8% among those with a bleeding-related and unknown rationale, respectively (P = 0.293). Conclusions: De-escalation, particularly non-bleeding-related de-escalation, of P2Y12 inhibitors is common. A substantial proportion of such de-escalation may be avoidable. Given the potential risk of ischemic complications, strategies should be considered to encourage both the upfront use of potent P2Y12 inhibitors and alternative strategies to de-escalation. Résumé: Contexte: La désescalade thérapeutique consistant à passer d'un inhibiteur puissant du récepteur plaquettaire P2Y12 au clopidogrel est pratique courante. En dépit de son fondement clinique, la désescalade non liée aux saignements lorsqu'une substitution d'inhibiteurs puissants est possible peut entraîner une augmentation du risque d'ischémie chez les patients. L'objectif de notre étude était d'analyser, dans un vaste registre clinique, l'amplitude du recours à la désescalade à partir d'un inhibiteur du récepteur P2Y12 et d’évaluer les conséquences possibles de la désescalade non liée aux saignements sur les résultats cliniques. Méthodologie: Une étude de cohorte rétrospective a été effectuée sur une série de patients consécutifs inscrits au registre CAPITAL (Cardiovascular Percutaneous Intervention Trial) afin de recenser ceux qui avaient fait l'objet d'un changement de traitement au cours de l'année suivant leur intervention coronarienne percutanée. Les désescalades ont été classées en deux catégories selon qu'elles étaient liées ou non liées aux saignements. Le critère d’évaluation principal, soit la survenue d'un événement cardiovasculaire indésirable majeur (ECIM), était un critère composite regroupant le décès, l'infarctus du myocarde et l'accident vasculaire cérébral. Les critères d’évaluation secondaires comprenaient chaque composante individuelle du critère composite et un critère d’évaluation de l'innocuité mesuré par le score TIMI (thrombolyse dans l'infarctus du myocarde) relatif aux saignements. Résultats: Sur 1854 patients, 209 (11,3 %) avaient fait l'objet d'une désescalade, qui était liée aux saignements dans 24,9 % des cas, non liée aux saignements dans 37,8 % des cas et sans raison indiquée dans 37,3 % des cas. Tous les patients ayant fait l'objet d'une désescalade non liée aux saignements étaient passés du ticagrélor au clopidogrel. Le critère d’évaluation principal a été observé chez 14 (6,7 %) patients, dont 50 % avaient fait l'objet d'une désescalade non liée aux saignements (p = 0,430). Parmi les patients ayant fait l'objet d'une désescalade non liée aux saignements, 7,6 % avaient été hospitalisés pour un infarctus du myocarde, comparativement à 1,9 % et 3,8 % des patients chez qui la désescalade était liée aux saignements ou n'avait pas de raison connue, respectivement (p = 0,293). Conclusions: La désescalade à partir d'inhibiteurs du récepteur P2Y12, et particulièrement la désescalade non liée aux saignements, est pratique courante, alors qu'elle pourrait être évitée dans une proportion élevée de cas. Compte tenu du risque de complications ischémiques d'une telle pratique, des stratégies devraient être envisagées afin d'encourager à la fois le recours dès le départ à des inhibiteurs puissants du récepteur P2Y12 et l'adoption de stratégies de remplacement de la désescalade.

The Coronavirus disease 2019 (COVID-19) pandemic has led to a significant increase in worldwide morbidity and mortality. Patients with COVID-19 are at risk for developing a variety of cardiovascular conditions including acute coronary syndromes, stress-induced cardiomyopathy, and myocarditis. Patients with COVID-19 who develop ST-elevation myocardial infarction (STEMI) are at a higher risk of morbidity and mortality when compared with their age- and sex-matched STEMI patients without COVID-19. We review current knowledge on the pathophysiology of STEMI in patients with COVID-19, clinical presentation, outcomes, and the effect of the COVID-19 pandemic on overall STEMI care.

We identified the prevalence of elevated high-sensitivity C-reactive protein and interleukin-6 in patients with recent cardiovascular (CV) events with or without prediabetes/diabetes, and in a control group of patients with remote CV events. Interleukin-6 was elevated in patients with prediabetes/diabetes and recent CV events (median, 4.84 pg/mL; interquartile range, 3.27-7.45) compared with patients with remote events (2.36 pg/mL; interquartile range, 1.09-4.00). There was a trend for elevated high-sensitivity C-reactive protein in patients with acute events and prediabetes/diabetes (P = 0.147). This supports the notion that patients with prediabetes/diabetes and recent CV events have higher inflammatory burdens than patients without recent CV events or dysglycemia. Résumé: Nous avons défini la prévalence de l’augmentation du taux de protéine C réactive à haute sensibilité et d’interleukine-6 chez des patients ayant récemment subi des événements cardiovasculaires (CV), atteints ou non de prédiabète ou de diabète, et dans un groupe témoin de patients ayant subi des événements CV antérieurement. Le taux d’interleukine-6 était élevé chez les patients atteints de prédiabète ou de diabète ayant récemment subi des événements CV (médiane de 4,84 pg/ml; écart interquartile de 3,27 à 7,45) par rapport aux patients ayant subi des événements antérieurement (2,36 pg/ml; écart interquartile de 1,09 à 4,00). Le taux de protéine C réactive à haute sensibilité avait tendance à être élevé chez les patients atteints de prédiabète ou de diabète ayant subi des événements aigus (p = 0,147). Ces données appuient la notion selon laquelle les patients atteints de prédiabète ou de diabète qui ont récemment subi des événements CV présentent des fardeaux inflammatoires supérieurs à ceux des patients qui n’ont pas récemment subi d’événements CV ou présenté de dysglycémie.

Coronary artery disease (CAD) is one of the major causes of death in the worldwide population. 1 Revascularization via percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) are current treatment modalities besides aggressive management of risk factors. Hence, accurate assessment and diagnosis of coronary artery disease is crucial in planning and implementing given treatment modality. Since the introduction of invasive coronary angiography (ICA) in 1958, it remains the most widely used modality to assess the anatomy and the extent of obstructive CAD. 2 In fact, indication for CABG or PCI and pre-procedural planning are commonly based on visualization of CAD via ICA. 3,4 While it allows assessment of coronary anatomy, degree of luminal obstruction, and blood flow, it is known to underestimate and/or overestimate lesion severity, especially for intermediate stenosis. 5 The major reason for this inaccurate eyeballing estimation is the transformation of a 3-dimensional (3D) lesion into a 2-dimensional image. Moreover, there is a significant interindividual examiner variation in the degree of lesion estimation. 6 Therefore, anatomical and morphological assessment of CAD is not only insufficient for understanding of the disease and coronary hemodynamics, but also for planning of complex interventions warranting additional functional and physiological assessment. Recent advances in invasive and noninvasive cardiac imaging such as fractional flow reserve (FFR), instantaneous wave-free ratio (iFR), intravascular ultrasound (IVUS), optical coherence tomography (OCT), near-infrared spectroscopy, coronary computed tomography angiogram (CCTA), positron emission tomography (PET), and single-photon emission computerized tomography myocardial perfusion imaging (MPI) allow more accurate assessment of a given lesion directing correct indication and planning of a given procedure. While their utility has been studied to variable extents in the context of PCI, there is a paucity, and in some of the modalities, there is a total absence of data in CABG.

Background The coronavirus disease 2019 (COVID-19) pandemic has impacted many aspects of ST-segment elevation myocardial infarction (STEMI) care, including timely access to primary percutaneous coronary intervention (PPCI). Objectives The goal of the NACMI (North American COVID-19 and STEMI) registry is to describe demographic characteristics, management strategies, and outcomes of COVID-19 patients with STEMI. Methods A prospective, ongoing observational registry was created under the guidance of 3 cardiology societies. STEMI patients with confirmed COVID+ (group 1) or suspected (person under investigation [PUI]) (group 2) COVID-19 infection were included. A group of age- and sex-matched STEMI patients (matched to COVID+ patients in a 2:1 ratio) treated in the pre-COVID era (2015 to 2019) serves as the control group for comparison of treatment strategies and outcomes (group 3). The primary outcome was a composite of in-hospital death, stroke, recurrent myocardial infarction, or repeat unplanned revascularization. Results As of December 6, 2020, 1,185 patients were included in the NACMI registry (230 COVID+ patients, 495 PUIs, and 460 control patients). COVID+ patients were more likely to have minority ethnicity (Hispanic 23%, Black 24%) and had a higher prevalence of diabetes mellitus (46%) (all p, Central Illustration

Adenosine boasts promising preclinical and clinical data supporting a vital role in modulating vascular homeostasis. Its widespread use as a diagnostic and therapeutic agent have been limited by its short half-life and complex biology, though adenosine-modulators have shown promise in improving vascular healing. Moreover, circulating adenosine has shown promise in predicting cardiovascular (CV) events. We sought to delineate whether circulating plasma adenosine levels predict CV events in patients undergoing invasive assessment for coronary artery disease. Patients undergoing invasive angiography had clinical data prospectively recorded in the Cardiovascular and Percutaneous ClInical TriALs (CAPITAL) revascularization registry and blood samples collected in the CAPITAL Biobank from which adenosine levels were quantified. Tertile-based analysis was used to assess prediction of major adverse cardiovascular events (MACE; composite of death, myocardial infarction, unplanned revascularization, and cerebrovascular accident). Secondary analyses included MACE subgroups, clinical subgroups and adenosine levels. There were 1,815 patients undergoing angiography who had blood collected with adenosine quantified in 1,323. Of those quantified, 51.0% were revascularized and 7.3% experienced MACE in 12 months of follow-up. Tertile-based analysis failed to demonstrate any stratification of MACE rates (log rank, P = 0.83), when comparing low-to-middle (hazard ratio (HR) 1.10, 95% confidence interval (CI) 0.68-1.78, P = 0.70) or low-to-high adenosine tertiles (HR 0.95, 95% CI 0.56-1.57, P = 0.84). In adjusted analysis, adenosine similarly failed to predict MACE. Finally, adenosine did not predict outcomes in patients with acute coronary syndrome nor in those revascularized or treated medically. Plasma adenosine levels do not predict subsequent CV outcomes or aid in patient risk stratification.

BACKGROUND Physician perception of procedural risk and clinical outcome can affect revascularization decision making. Public reporting of percutaneous coronary intervention outcomes accentuates the need for accuracy in risk prediction in order to avoid a treatment paradox of undertreating the highest risk patients. Our study compares a validated risk score to physician prediction (PP) of 1-year mortality based on clinical impression at the time of invasive angiography. METHODS AND RESULTS We performed a cohort study between August 2015 and May 2018 to determine the discriminative accuracy of interventional cardiologists on one-year mortality of the treated patient. PP of one-year mortality was compared to the New York State Percutaneous Coronary Intervention Reporting System (NYPCIRS) score in predicting mortality. Three thousand seven hundred ninety-two patients were followed with a median follow-up period of 14.4 months (interquartile range 12.4-18.1 months) and 165 patients (4.4%) died within one-year. PP of mortality was associated with one-year mortality with a hazard ratio of 8.78 (95% confidence interval 5.24-14.71, P < 0.0001). Clinical presentation in the form of cardiogenic shock, return of spontaneous circulation, and liver and renal dysfunction were associated with PP. Diagnostic accuracy and specificity were improved in PP compared to NYPCIRS. The combination of PP to NYPCIRS improved the overall c-statistic and diagnostic yield. CONCLUSION PP appears to be especially specific and accurate for prediction of mortality compared to NYPCIRS though it lacks sensitivity. Furthermore, the combination of PP with NYPCIRS improved the c-statistic and diagnostic yield. Overall, the utility of PP with an objective risk score improves the diagnostic accuracy of mortality prediction.

Myocardial blood flow (MBF) quantification by Rubidium-82 positron emission tomography (PET) has shown promise for cardiac allograft vasculopathy (CAV) surveillance and risk stratification post heart transplantation. The objective was to determine the prognostic value of serial PET performed early post transplantation. Heart transplant (HT) recipients at the University of Ottawa Heart Institute with 2 PET examinations (PET1 = baseline, PET2 = follow-up) within 6 years of transplant were included in the study. Evaluation of PET flow quantification included stress MBF, coronary vascular resistance (CVR), and myocardial flow reserve (MFR). The primary composite outcome was all-cause death, re-transplant, myocardial infarction, revascularization, allograft dysfunction, cardiac allograft vasculopathy (CAV), or heart failure hospitalization. A total of 121 patients were evaluated (79% male, mean age 56 ± 11 years) with consecutive scans performed at mean 1.4 ± 0.7 and 2.6 ± 1.0 years post HT for PET1 and PET2, respectively. Over a mean follow-up of 3.0 (IQR 1.8, 4.6) years, 26 (22%) patients developed the primary outcome: 1 death, 11 new or progressive angiographic CAV, 2 percutaneous coronary interventions, 12 allograft dysfunction. Unadjusted Cox analysis showed a significant reduction in event-free survival in patients with PET1 stress MBF 76 (HR: 2.19, 95% CI 0.87-5.51 P = 0.045). There was no association between MFR and outcomes. Low-stress MBF and persistent increased CVR on serial PET imaging early post HT are associated with adverse cardiovascular outcomes. Early post-transplant and longitudinal assessment by PET may identify at-risk patients for increased surveillance post HT.

Purpose: The impact of cardiology fellows (CFs) and interventional cardiology fellows (ICFs) on patient radiation and contrast exposure during diagnostic coronary angiography and percutaneous coronary intervention is unknown. Methods: Between 2011 and 2014, 16,175 cases were retrospectively assessed involving 27 CFs, 22 ICFs and 24 staff as primary operators. Results: During diagnostic coronary angiography, ICFs administered the lowest radiation dose (5,648±5,523 cGy*cm2; 1.30 ± 1.27 mSv)—achieving 22% less radiation than the staff (6,889±4,294 cGy*cm2; 1.58 ± 0.99 mSv) and 36% less than CFs (7,700±6,751 cGy*cm2; 1.77 ± 1.55 mSv) (p

We previously demonstrated high diagnostic accuracy of Rubidium-82 positron emission tomography (PET) myocardial blood flow (MBF) quantification for CAV. The purpose of this study was to validate multiparametric PET detection of CAV by combined rate-pressure-product-corrected myocardial flow reserve (cMFR), stress MBF, and coronary vascular resistance (CVR) assessment. Diagnostic CAV cut-offs of cMFR 55 determined in a previous study (derivation) were assessed in heart transplant recipients referred for coronary angiography and intravascular ultrasound (IVUS) (validation). CAV was defined as International Society of Heart and Lung Transplantation CAV1-3 on angiography; and maximal intimal thickness ≥ 0.5 mm on IVUS. Eighty patients (derivation n = 40, validation n = 40) were included: 80% male, mean age 54±14 years, 4.5±5.6 years post transplant. The prevalence of CAV was 44% on angiography and 78% on IVUS. Combined PET cMFR 55 CAV assessment yielded high 88% (specificity 75%) and 83% (specificity 40%) sensitivity for ≥ 1 abnormal parameter and high 88% (sensitivity 59%) and 90% (sensitivity 43%) specificity for 3 abnormal parameters, in the derivation and validation cohorts, respectively. We validate the diagnostic accuracy of multiparametric PET flow quantification by cMFR, stress MBF, and CVR for CAV.

Dual antiplatelet therapy (DAPT) with aspirin and a P2Y12 inhibitor is prescribed for 1-year after myocardial infarction. Two clinical strategies are considered at 1-year: continuation of DAPT or "Dual Pathway" (DP), using aspirin and rivaroxaban. No head-to-head comparative studies exist. In our

Atherosclerosis remains a leading cause of morbidity and mortality, with revascularization remaining a cornerstone of management. Conventional revascularization modalities remain challenged by target vessel reocclusion-an event driven by mechanical, thrombotic, and proliferative processes. Despite considerable advancements, restenosis remains the focus of ongoing research. Adjunctive agents, including dipyridamole, offer a multitude of effects that may improve vascular homeostasis. We sought to quantify the potential therapeutic impact of dipyridamole on vascular occlusion. We performed a literature search (EMBASE and MEDLINE) examining studies that encompassed 3 areas: (1) one of the designated medical therapies applied in (2) the setting of a vascular intervention with (3) an outcome including vascular occlusion rates and/or quantification of neointimal proliferation/restenosis. The primary outcome was vascular occlusion rates. The secondary outcome was the degree of restenosis by neointimal quantification. Both human and animal studies were included in this translational analysis. There were 6,839 articles screened, from which 73 studies were included, encompassing 16,146 vessels followed up for a mean of 327.3 days (range 7-3650 days). Preclinical studies demonstrate that dipyridamole results in reduced vascular occlusion rates {24.9% vs. 48.8%, risk ratio 0.53 [95% confidence interval (CI) 0.40-0.70], I2 = 39%, P < 0.00001}, owing to diminished neointimal proliferation [standardized mean differences -1.13 (95% CI -1.74 to -0.53), I2 = 91%, P = 0.0002]. Clinical studies similarly demonstrated reduced occlusion rates with dipyridamole therapy [23.5% vs. 31.0%, risk ratio 0.77 (95% CI 0.67-0.88), I2 = 84%, P < 0.0001]. Dipyridamole may improve post-intervention vascular patency and mitigate restenosis. Dedicated studies are warranted to delineate its role as an adjunctive agent after revascularization.

Background: Transradial access (TRA) has emerged as the preferred vascular access site for coronary angiography and percutaneous coronary intervention. This systematic review and meta-analysis was performed to evaluate 30-day all-cause mortality comparing TRA with transfemoral access for percutaneous coronary intervention in patients with ST-segment–elevation myocardial infarction. Methods: We performed a systematic literature search and meta-analysis of randomized controlled studies published from inception until January 7, 2020, in MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Web of Science Core Collection. Preferred Reported Items for Systematic Reviews and Meta-Analyses guidelines were used for abstracting data. The primary outcome was all-cause mortality at 30 days. Secondary outcomes included myocardial infarction, major bleeding, stroke, and access site complications. Results: A total of 14 studies representing 11 707 patients (5802 patients with TRA; 5905 patients with transfemoral access) were included in this systematic review. All-cause mortality (N=8 studies) was significantly reduced in the TRA group with an overall risk ratio (RR) of 0.72 (95% CI, 0.56–0.92) in the pooled analysis. Major bleeding (N=12 studies; RR, 0.60 [95% CI, 0.45–0.80]) and access site complications (N=9 studies; RR, 0.40 [95% CI, 0.30–0.53]) were significantly higher in the transfemoral access group. There was no statistical difference in reinfarction (N=10 studies; RR, 0.96 [95% CI, 0.75–1.25]) or stroke (N=8 studies; RR, 1.47 [95% CI, 0.87–2.50]). Conclusions: TRA is associated with lower 30-day mortality, major bleeding, and access site complications when compared with transfemoral access in ST-segment–elevation myocardial infarction patients who undergo percutaneous coronary intervention. Registration: URL: https://www.crd.york.ac.uk/PROSPERO/ ; Unique identifier: 127955.

This review describes the current evidence and controversies for viability imaging to direct revascularization decisions and the impact on patient outcomes. Balancing procedural risks and possible benefit from revascularization is a key question in patients with heart failure of ischemic origin (IHF). Different stages of ischemia induce adaptive changes in myocardial metabolism and function. Viable but dysfunctional myocardium has the potential to recover after restoring blood flow. Modern imaging techniques demonstrate different aspects of viable myocardium; perfusion (single-photon emission computed tomography [SPECT], positron emission tomography [PET], cardiovascular magnetic resonance [CMR]), cell metabolism (PET), cell membrane integrity and mitochondrial function (201Tl and 99mTc-based SPECT), contractile reserve (stress echocardiography, CMR) and scar (CMR). Observational studies suggest that patients with IHF and significant viable myocardium may benefit from revascularization compared with medical treatment alone but that in patients without significant viability, revascularization appears to offer no survival benefit or could even worsen the outcome. This was not supported by 2 randomized trials (Surgical Treatment for Ischemic Heart Failure [STICH] and PET and Recovery Following Revascularization [PARR] -2) although post-hoc analyses suggest that benefit can be achieved if decisions had been strictly based on viability imaging recommendations. Based on current evidence, viability testing should not be the routine for all patients with IHF considered for revascularization but rather integrated with clinical data to guide decisions on revascularization of high-risk patients with comorbidities.

BACKGROUND The Coordinated National Network to Engage Cardiologists in the antithrombotic Treatment of patients with Atrial Fibrillation undergoing Percutaneous Coronary Intervention (CONNECT AF+PCI-I) program provided a snapshot (Nov 2015-Jul 2018) of the antithrombotic management of 467 non-valvular atrial fibrillation (NVAF) patients undergoing PCI in Canada (Bagai et al Can J Cardiol 2018;34:S16). Since then, further randomized clinical trials have supported updated Canadian Cardiovascular Society (CCS) AF and Antiplatelet guideline recommendations for antithrombotic strategies for NVAF and coronary artery disease (CAD) patients undergoing PCI and/or medical management. Thus, an updated quality enhancement assessment in Canadian practice (CONNECT AF+PCI-II) was undertaken. METHODS AND RESULTS By retrospective chart audit (Aug 2018-Dec 2020), 68 cardiologists from 8 provinces identified 626 patients with NVAF. 37% had stable CAD, 56% had an acute coronary syndrome (ACS) and PCI, and 7% had an ACS and were medically managed. Median age was 76 (25th,75th percentiles 69, 83; 87% ≥65 years); 29% female; 38% diabetes; median CHADS2 score 2 (1, 3); median CHA2DS2-VASc score 4 (3, 5); median HAS-BLED score 3 (2, 3). 73% were receiving oral anticoagulation (OAC) before the index ACS/PCI (apixaban 31%, rivaroxaban 24%, dabigatran 6%, edoxaban 2%, warfarin 10%). Initial antithrombotic therapy after the index ACS/PCI was: 53% triple therapy (OAC+dual antiplatelet therapy [DAPT=ASA+P2Y12 receptor inhibitor], 31% OAC+P2Y12 inhibitor, 9% DAPT, 4% OAC+ASA, 2% OAC alone, and CONCLUSION While triple therapy remains the most common initial antithrombotic strategy used in AF patients undergoing PCI and/or admitted with ACS in Canada, treatment duration has shortened over time. Further, more patients are receiving CCS guideline-recommended OAC+ P2Y12 receptor inhibitor post-PCI compared to previously, and OAC monotherapy 1 year post-ACS/PCI.

BACKGROUND In patients with ST-segment elevation myocardial infarction (STEMI), presentation during off-hours may have an impact on clinical outcomes. Research in this area is not only scarce, but also conflicting. This study investigated the relationship between off-hours presentation and in-hospital clinical outcomes in patients presenting with STEMI. METHODS AND RESULTS We included all consecutive STEMI patients referred to the University of Ottawa Heart Institute as part of a primary percutaneous coronary intervention (PCI) strategy between July 2004 and December 2017 inclusive. Patients were included if they had =1mm ST-segment elevation in two contiguous leads on a 12-lead ECG. Patients who received fibrinolysis or required therapeutic hypothermia were excluded. Patients were stratified into two groups based on the time of presentation at the PCI center: Group 1 consisted of patients presenting during on-hours defined as between 08:00 and 17:59 hrs; Group 2 consisted of patients presenting during the off-hours defined as 18:00 and 07:59 hrs, on weekends, or statutory holidays. The primary outcome was defined as in-hospital mortality. We identified 5626 patients meeting the inclusion criteria: 2150 (38%) in the on-hours group, and 3476 (62%) in the off-hours group. At baseline, the two groups were similar except for lower rates of diabetes (17.6% vs. 20.4%, p=0.01) and smokers (38.2% vs. 41.5%, p=0.02) in the on-hours group. The median door-to-balloon time was 77 min (interquartile range [IQR]: 43-116) in the on-hours group and 102 min (IQR: 76-134) in the off-hours group (p CONCLUSION Patients who presented for primary PCI during regular hours had significantly lower in-hospital mortality as compared to patients presenting during off-hours.

Although the incidence of ST-elevation myocardial infarction (STEMI) is on the decline, management of patients who present with STEMI continues to require significant health care resources. Earlier hospital discharge in low-risk patients who present with STEMI has been an area of focus in an attempt to reduce health care costs. As a result, discharge within 48-72 hours after successful primary percutaneous coronary intervention has increasingly become routine practice. Moreover, the current COVID-19 pandemic has led to enormous pressure on health care systems to find ways to increase bed capacity, preserve resources, and reduce the risk of exposure to patients and health care workers. In response to this goal, the Ottawa Heart Institute has developed and implemented a novel Very Early Hospital Discharge (VEHD) protocol. The VEHD protocol is a simple, 4-step algorithm designed to accurately and efficiently identify low-risk STEMI patients who can be safely discharged between 20 and 36 hours after successful primary percutaneous coronary intervention. When deemed eligible for VEHD predischarge tasks are completed by the treating medical and nursing team and the patient is discharged home. Follow-up is completed remotely via virtual care (48 hours, 7 days, 30 days), and in the outpatient cardiology clinic (4-6 weeks). Amid a worldwide COVID-19 pandemic we believe the VEHD protocol is a crucial step in maintaining exceptional quality of care, in terms of patient satisfaction and clinical outcomes, while concurrently decreasing the risk of nosocomial infections, and reducing resource utilization.

Background Dual antiplatelet therapy (DAPT) is the standard of care following PCI. DAPT reduces ischemic events but increases bleeding risk. Duration of DAPT following PCI remains controversial. Current guidelines recommend duration be individualized based on risk of ischemia and bleeding. Although multiple strategies exist to risk stratify patients, including application of the PRECISE-DAPT and DAPT scores, there is currently no standardized risk assessment protocol. Purpose To determine if the PRECISE-DAPT and DAPT scores can identify patients at increased risk of ischemia or bleeding in a cohort prescribed 12 months of DAPT following PCI. Methods We calculated the PRECISE-DAPT and DAPT scores for 469 consecutive patients at baseline after PCI. Patients were grouped based on score treatment recommendation; PRECISE-DAPT prolonged or shortened (PRECISE DAPT Results Among 469 patients, mean age was 64.4 (SD 12.2); 102 (21.7%) were women. Index presentation consisted of a STEMI in 207 (44.1%), NSTEMI in 99 (21.1%), and UA in 60 (12.8%). At presentation, 174 (37.1%) were current smokers, 115 (24.5%) had a prior MI, 118 (25.2%) had diabetes, 249 (53.1%) had dyslipidemia and 281 (60.0%) were previously diagnosed as hypertensive. Overall, there was an increase in bleeding and no difference in MACE for patients with a PRECISE-DAPT score ≥25 (13.3% vs. 4.1% P Conclusion A PRECISE-DAPT score ≥25 was associated with an increased rate of bleeding and no difference in MACE in patients prescribed 12 months of DAPT. This supports the use of the PRECISE-DAPT as a prospective tool in clinical practice. Funding Acknowledgement Type of funding source: None

Background Acute kidney injury (AKI) complicating primary percutaneous coronary intervention (PCI) is an independent predictor of short- and long-term outcomes in patients presenting with ST-elevation myocardial infarction (STEMI). Prior studies suggest a lower incidence of AKI in patients undergoing PCI through radial artery compared to femoral artery access; however, no randomized clinical trials have specifically investigated this question in patients presenting with STEMI. Methods To determine whether radial access (RA) is associated with a reduced frequency of AKI following primary PCI, we performed a substudy of the SAFARI-STEMI trial. The SAFARI-STEMI trial was an open-label, multicenter trial, which randomized patients presenting with STEMI to RA or femoral access (FA), between July 2011 and December 2018. The primary outcome of this post hoc analysis was the incidence of AKI, defined as an absolute (>0.5 mg/dL) or relative (>25%) increase in serum creatinine from baseline. Results In total 2,285 (99.3%) of the patients enrolled in SAFARI-STEMI were included in the analysis—1,132 RA and 1,153 FA. AKI occurred in 243 (21.5%) RA patients and 226 (19.6%) FA patients (RR: 0.91, 95% CI: 0.78-1.07, P = .27). An absolute increase in serum creatinine >0.5 mg/dL was seen in 49 (4.3%) radial and 52 (4.5%) femoral patients (RR: 1.04, 95% CI: 0.71-1.53, P = .83). AKI was lower in both groups when the KDIGO definition was applied (RA 11.9% vs FA 10.8%; RR: 0.90, 95% CI: 0.72-1.13, P = .38). Conclusions Among STEMI patients enrolled in the SAFARI-STEMI trial, there was no association between catheterization access site and AKI, irrespective of the definition applied. These results challenge the independent association between catheterization access site and AKI noted in prior investigations.

Myocardial blood flow (MBF) quantification by Rubidium-82 positron emission tomography (PET) has shown promise for cardiac allograft vasculopathy (CAV) surveillance and risk stratification post heart transplantation. The objective was to determine the prognostic value of serial PET performed early post transplantation.Heart transplant (HT) recipients at the University of Ottawa Heart Institute with 2 PET examinations (PET1 = baseline, PET2 = follow-up) within 6 years of transplant were included in the study. Evaluation of PET flow quantification included stress MBF, coronary vascular resistance (CVR), and myocardial flow reserve (MFR). The primary composite outcome was all-cause death, re-transplant, myocardial infarction, revascularization, allograft dysfunction, cardiac allograft vasculopathy (CAV), or heart failure hospitalization. A total of 121 patients were evaluated (79% male, mean age 56 ± 11 years) with consecutive scans performed at mean 1.4 ± 0.7 and 2.6 ± 1.0 years post HT for PET1 and PET2, respectively. Over a mean follow-up of 3.0 (IQR 1.8, 4.6) years, 26 (22%) patients developed the primary outcome: 1 death, 11 new or progressive angiographic CAV, 2 percutaneous coronary interventions, 12 allograft dysfunction. Unadjusted Cox analysis showed a significant reduction in event-free survival in patients with PET1 stress MBF 2.1 (HR: 2.43, 95% CI 1.11-5.29 P = 0.047) and persistent abnormal PET1 to PET2 CVR 76 (HR: 2.19, 95% CI 0.87-5.51 P = 0.045). There was no association between MFR and outcomes.Low-stress MBF and persistent increased CVR on serial PET imaging early post HT are associated with adverse cardiovascular outcomes. Early post-transplant and longitudinal assessment by PET may identify at-risk patients for increased surveillance post HT.

We previously demonstrated high diagnostic accuracy of Rubidium-82 positron emission tomography (PET) myocardial blood flow (MBF) quantification for CAV. The purpose of this study was to validate multiparametric PET detection of CAV by combined rate-pressure-product-corrected myocardial flow reserve (cMFR), stress MBF, and coronary vascular resistance (CVR) assessment.Diagnostic CAV cut-offs of cMFR 2.9, stress MBF 2.3, CVR 55 determined in a previous study (derivation) were assessed in heart transplant recipients referred for coronary angiography and intravascular ultrasound (IVUS) (validation). CAV was defined as International Society of Heart and Lung Transplantation CAVWe validate the diagnostic accuracy of multiparametric PET flow quantification by cMFR, stress MBF, and CVR for CAV.

Background Dual antiplatelet therapy (DAPT), with aspirin and a P2Y12 inhibitor, is the standard therapy for patients following PCI. Duration of treatment with DAPT has been controversial despite large studies. Current guidelines recommend treatment duration be individualized based on risk of ischemia and bleeding. To facilitate treatment decisions, risk assessment tools, including the DAPT and PRECISE-DAPT scores, have been developed. Purpose As components of these scores differ, the variability of recommendation remains unknown. We set to evaluate inter-tool concordance in treatment recommendation in a cohort of patients after PCI. Methods Using data from our local PCI registry, we calculated the PRECISE-DAPT at baseline following PCI and the DAPT after 1 year of treatment for 311 consecutive patients with complete data for both scores to be calculated. Based on their DAPT and PRECISE-DAPT scores, patients were grouped into concordant for long-term treatment (DAPT ≥2 and PRECISE-DAPT Results Among the 311 patients, mean age was 63.4 (SD 11.6); 245 (79%) were men, 93 (29.9%) had history of a prior MI, 130 (41.8%) were current smokers, 32 (10.3%) had a history of CHF or LVEF Concordance Analysis PRECISE-DAPT Score Recommendation Long Term (N=245) Shortened (N=66) DAPT Score Recommendation Long Term (N=162) 136 (43.7%) 26 (8.4%) Concordant for Long Term Treatment Shortened (N=149) 109 (35%) 40 (12.8%) Concordant for Shortened Treatment Conclusion Comparison of the DAPT score and the PRECISE-DAPT score showed concordance in treatment recommendation in only 56.6% of patients. Given the poor agreement between these tools, prospective concurrent evaluations and correlation to outcomes will be required in future studies.

Background Large increases in myocardial trace elements may adversely affect metabolism and become detrimental to cardiac function. Percutaneous coronary intervention (PCI) allows for the revascularisation of obstructive coronary artery disease using drug-eluting stents. These stents are comprised of a metallic stent backbone covered in an engineered polymer which delivers a drug over a prescribed period to the vessel wall. Given the potential implications of trace metal accumulation within the myocardium, our goal is to determine if metallic coronary stents are able to cause detectable elevations in serum cobalt and/or chromium levels. Methods This study was a single centre, observational, pilot study with 20 patients who underwent planned PCI with implantation of a cobalt chromium drug eluting stent. Serum blood samples were drawn at baseline prior to PCI, 4 hours post-stent deployment and at the time of routine follow-up after PCI. All blood samples were analysed for cobalt and chromium concentrations. The primary outcome of this study was the difference in serum cobalt and chromium levels at routine clinical follow-up. Results The mean follow up was 64.1 ± 17.3 days. There was no difference in serum cobalt levels when comparing baseline and routine clinical follow up (3.32 ± 2.14 nmol/L vs. 3.14 ± 1.00 nmol/L, p = 0.99) nor in chromium levels (4.24 ± 2.31 nmol/L vs. 2.82 ± 1.22 nmol/L, p = 0.11). There was also no difference between baseline and 4 hours post-PCI serum concentrations. Conclusions Percutaneous coronary intervention with cobalt chromium coronary stents does not appear to cause an elevation in these trace element serum concentrations.

BACKGROUND: Radial artery access is commonly performed for coronary angiography and invasive hemodynamic monitoring. Despite limitations in diagnostic accuracy, the modified Allen test (manual occlusion of radial and ulnar arteries followed by release of the latter and assessment of palmar blush) is used routinely to evaluate the collateral circulation to the hand and, therefore, to determine patient eligibility for radial artery access. We sought to evaluate whether a smartphone application may provide a superior alternative to the modified Allen test. METHODS: We compared the modified Allen test with a smartphone heart rate–monitoring application (photoplethysmography readings detected using a smartphone camera lens placed on the patient’s index finger) in patients undergoing a planned cardiac catheterization. Test order was randomly assigned in a 1:1 fashion. All patients then underwent conventional plethysmography of the index finger, followed by Doppler ultrasonography of the radial and ulnar arteries (the diagnostic standard). The primary outcome was diagnostic accuracy of the heart rate–monitoring application. RESULTS: Among 438 patients who were included in the study, we found that the heart rate–monitoring application had a superior diagnostic accuracy compared with the modified Allen test (91.8% v. 81.7%, p = 0.002), attributable to its greater specificity (93.0% v. 82.8%, p = 0.001). We also found that this application had greater diagnostic accuracy for assessment of radial or ulnar artery patency in the ipsilateral and contralateral wrist (94.0% v. 84.0%, p INTERPRETATION: A smartphone application used at the bedside was diagnostically superior to traditional physical examination for confirming ulnar patency before radial artery access. This study highlights the potential for smartphone-based diagnostics to aid in clinical decision-making at the patient’s bedside. Trial registration: Clinicaltrials.gov, no. NCT02519491.

Background: Clinical outcomes in acute coronary syndrome patients treated with P2Y12 inhibitors who require urgent coronary artery bypass grafting (CABG) have not been well studied. Methods: We examined clinical outcomes in acute coronary syndrome patients in relation to the timing of CABG following P2Y12 inhibitor discontinuation (5 days). The primary ischemic outcome was a composite of death, reinfarction, need for revascularization, or stroke. The primary safety outcome was bleeding of at least moderate severity as defined by a Universal Definition of Perioperative Bleeding class ≥2. Results: Among 508 patients (95 ticagrelor, 413 clopidogrel), the timing of CABG following P2Y12 inhibitor discontinuation was 5 days in 44.7%. Compared with CABG within 72 h, CABG 72 h to five days (adjusted odds ratio (OR) 0.35; 95% confidence interval (CI) 0.14–0.85; p=0.02) but not >5 days (adjusted OR 0.62; 95% CI 0.33–1.16; p=0.14) after P2Y12 inhibitor discontinuation was associated with lower odds of the primary ischemic outcome. Compared with CABG within 72 h, CABG 72 h to five days (adjusted OR 0.38; 95% CI 0.22–0.66; p=0.001) and >5 days (adjusted OR 0.33; 95% CI 0.20–0.53; p12 inhibitor discontinuation were associated with lower rates of Universal Definition of Perioperative Bleeding class ≥2 bleeding. Conclusions: CABG within 72 h after P2Y12 inhibitor discontinuation is associated with excess ischemia and bleeding. The rates of ischemic and bleeding events were comparable in patients undergoing CABG 72 h to five days compared with >5 days after P2Y12 inhibitor discontinuation.

Objectives: Mitigating the gastrointestinal (GI) bleeding risks of dual antiplatelet therapy (DAPT) is a common clinical concern. While proton pump inhibitors (PPIs) remain the most effective therapy, their adverse events warrant considering alternatives, including Histamine 2 receptor antagonists (H2RAs). Methods: We searched for randomized controlled trials in MEDLINE, EMBASE, PubMed, and Cochrane Central Register of Controlled Trials, published from 1980 to 2016. After screening, 10 trials were eligible. We compared PPIs to H2RAs in patients on DAPT in terms of 2 clinical and one laboratory outcomes; GI complications, major adverse cardiovascular events (MACE) and high on-treatment platelet reactivity (HTPR). Clinical and statistical inter-study heterogeneity was low for all 3 outcomes (I2 = 0%, p > 0.05 for all). Results: Fixed effects meta-analysis suggested that PPIs were superior to H2RAs in preventing GI complications (OR 0.28, 95% CI 0.17–0.48) but with higher risk of HTPR (OR 1.28, 95% CI 1.030–1.60) though without a higher incidence of MACE (OR 0.99, 95% CI 0.55–1.77). Conclusions: PPIs are superior to H2RAs for gastroprotection in patients on DAPT. However, PPIs are associated with HTPR, with no significant difference demonstrated in MACE. Based on currently available data, the use of PPIs may be warranted in selected patients on DAPT deemed at risk for GI complications.

Background Early stent thrombosis (ST) remains an important complication of primary percutaneous intervention (PCI). To date, our information on angiographic and clinical predictors of early ST in ST-segment elevation myocardial infarction (STEMI) patients treated with primary PCI is limited. Methods We tried to evaluate the incidence, predictors, and outcomes of early ST in real-world patients treated with primary PCI. We identified all the patients presenting with STEMI between June 2004 and January 2011 who underwent primary PCI as the primary mode of revascularization. Diagnosis of ST was made as per the standard definition proposed by the Academic Research Consortium. Results The incidence of early ST was 1% among 2,303 patients treated with primary PCI. Definite and probable early ST occurred in 22 and 2 patients, respectively. Patients with early ST had higher in-hospital (P = 0.03) and 30-day mortality (P = 0.048). The rate of cardiogenic shock (P = 0.0006) and cerebrovascular accident (P = 0.0004) was also greater in the early ST group. Smaller stent diameter and lower use of intracoronary glycoprotein IIb/IIIa inhibitor were associated with higher rate of early ST. There was a trend of higher bivalirudin use in ST group, which did not reach significance (P = 0.07) On IVUS imaging, stent malapposition and uncovered plaque area were noted in 6 out of 11 cases. Conclusion The incidence of early ST in primary PCI cohort is low. However, it is still associated with higher mortality and morbidity. Small stent diameter and disuse of intracoronary glycoprotein IIb/IIIa inhibitor may be associated with early ST.

SummaryTicagrelor has been endorsed by guidelines as the P2Y12 inhibitor of choice in patients with acute coronary syndrome. Clinically, some patients on ticagrelor will require a switch to clopidogrel; however, the optimal strategy and pharmacodynamics effects of switching remain unknown. Patients with an indication to switch were randomly assigned to either a bolus arm (Clopidogrel 600 mg bolus followed by 75 mg daily, n=30) or a no-bolus arm (Clopidogrel 75 mg daily, n=30). Blood samples were collected at baseline, 12, 24, 48, 54, 60 and 72 hours (h) for assessment of platelet reactivity. The primary outcome was P2Y12 reactivity units (PRU) at 72 h. Secondary outcomes included: PRUs at each time point, incidence of high on-treatment platelet reactivity (HPR), major adverse cardiac events (MACE) and TIMI bleeding at 30 days. Serial PRUs increased after switching to clopidogrel in both groups. At 72 h, no difference in PRU was observed (165.8 ± 71.0 vs 184.1 ± 67.7, bolus vs no bolus, respectively, p=0.19). At 48 h the PRUs were significantly lower in the bolus arm (114 ± 73.1 vs 165.1 ± 70.5, respectively; p=0.0076) and at 72 h, there was a significant reduction in incidence of HPR (26.7 % vs 56.7 %, p=0.02). No differences in MACE or TIMI bleeding were observed. Although a bolus strategy was not associated with improved platelet inhibition at 72 h; at 48 h, platelet inhibition was superior with reduced incidence of HPR. Larger studies will be required to determine its clinical significance. Until then, decision for giving a bolus of clopidogrel at the time of a switch may in part be dependent on the indication for switching, especially if there are concerns for bleeding risk.Supplementary Material to this article is available online at www.thrombosis-online.com.

Purpose Intravascular ultrasound (IVUS) assessment of cardiac allograft vasculopathy (CAV) provides diagnostic and prognostic information. Multivessel analysis has high sensitivity for detecting CAV, but is time consuming, costly and associated with procedural risks compared to single-vessel examination. We evaluated the regional distribution and plaque characteristics of CAV to guide clinical evaluation by IVUS. Methods Consecutive heart transplant recipients referred for coronary angiography were prospectively evaluated with multivessel IVUS. Quantitative IVUS analysis was performed for every 1 mm axial slice to determine average maximal intimal thickness, intimal area and percentage intimal area. Virtual histology was utilized for plaque characterization. Results Forty patients completed evaluation at 4.8 ± 5.8 years post-transplant: mean age 56 ± 14 years, 31 (78%) male. Angiographic disease was present in 14 (35%) patients: 9 (23%) CAV1, 2 (5%) CAV2, 3 (8%) CAV3. Maximal stenosis was greater in the LAD (median 34% (IQR 20, 63) vs. 19% (IQR 0, 29) for LCx, 0% (IQR 0, 18) for RCA, (p=0.001)) and proximal segments (median 17% (IQR 12, 29) vs. 13% (IQR 9, 23) for mid, 12% (IQR 8, 16) for distal segments, p=0.005). A total of 268 segments in 101 vessels (40 left anterior descending (LAD), 35 circumflex (LCx), 26 right coronary artery (RCA)) were analyzed with IVUS. Mean coronary length examined was 64 ± 15 mm. Intimal disease on IVUS was greater in the LAD and proximal coronary segments (Table). On virtual histology, plaque composition was predominantly mixed atheromatous fibrotic and more prevalent in the LAD (72%) vs. LCx (54%) and RCA (42%), p=0.043. There was no isolated fibrotic plaque and low 13% prevalence of vulnerable thin cap fibroatheroma plaque. Conclusion There is heterogeneous distribution of CAV with high disease burden in the LAD and proximal coronary segments. Single-vessel IVUS examination for CAV, beginning in the LAD could avoid risks of multivessel examination.