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Introduction: The electrocardiogram (ECG) is a valuable tool for the diagnosis of myocardial ischemia as it presents distinctive ischemic patterns. Deep learning methods such as convolutional neural networks (CNN) are employed to extract data-derived features and to recognize natural patterns. Hence, CNN enable an unbiased view on well-known clinical phenomenon, e.g., myocardial ischemia. This study tested a novel, hypothesis-generating approach using pre-trained CNN to determine the optimal ischemic parameter as obtained from the highly susceptible intracoronary ECG (icECG)., Method: This was a retrospective observational study in 228 patients with chronic coronary syndrome. Each patient had participated in clinical trials with icECG recording and ST-segment shift measurement at the beginning (i.e., non-ischemic) and the end (i.e., ischemic) of a one-minute proximal coronary artery balloon occlusion establishing the reference. Using these data (893 icECGs in total), two pre-trained, open-access CNN (GoogLeNet/ResNet101) were trained to recognize ischemia. The best performing CNN during training were compared with the icECG ST-segment shift for diagnostic accuracy in the detection of artificially induced myocardial ischemia., Results: Using coronary patency or occlusion as reference for absent or present myocardial ischemia, receiver-operating-characteristics (ROC)-analysis of manually obtained icECG ST-segment shift (mV) showed an area under the ROC-curve (AUC) of 0.903±0.043 (p<0.0001, sensitivity 80%, specificity 92% at a cut-off of 0.279mV). The best performing CNN showed an AUC of 0.924 (sensitivity 93%, specificity 92%). DeLong-Test of the ROC-curves showed no significant difference between the AUCs. The underlying morphology responsible for the network prediction differed between the trained networks but was focused on the ST-segment and the T-wave for myocardial ischemia detection., Conclusions: When tested in an experimental setting with artificially induced coronary artery occlusion, quantitative icECG ST-segment shift and CNN using pathophysiologic prediction criteria detect myocardial ischemia with similarly high accuracy., Competing Interests: The authors have declared that no competing interests exist.

Introduction: In patients with chronic coronary syndrome, percutaneous coronary intervention targets haemodynamically significant stenoses, that is, those thought to cause ischaemia. Intracoronary ECG (icECG) detects ischaemia directly where it occurs. Thus, the goal of this study was to test the accuracy of icECG during pharmacological inotropic stress to determine functional coronary lesion severity in comparison to the structural parameter of quantitative angiographic per cent diameter stenosis (%S), as well as to the haemodynamic indices of fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR)., Method: The primary study endpoint of this prospective trial was the maximal change in icECG ST-segment shift during pharmacological inotropic stress induced by dobutamine plus atropine obtained within 1 min after reaching maximal heart rate(=220 - age). IcECG was acquired by attaching an alligator clamp to the angioplasty guidewire positioned downstream of the stenosis. For the pressure-derived stenosis severity ratios, coronary perfusion pressure and simultaneous aortic pressure were continuously recorded., Results: There was a direct linear relation between icECG ST-segment shift and %S: icECG=-0.8+0.03*%S (r 2 =0.164; p<0.0001). There were inverse linear correlations between FFR and %S: FFR=1.1-6.1*10-3*%S (r 2 =0.494; p<0.0001), and between iFR and %S: iFR=1.27-8.6*10-3*%S (r 2 =0.461; p<0.0001). Using a %S-threshold of ≥50% as the reference for structural stenosis relevance, receiver operating characteristics-analysis of absolute icECG ST-segment shift during hyperemia showed an area under the curve (AUC) of 0.678±0.054 (p=0.002; sensitivity=85%, specificity=50% at 0.34 mV). AUC for FFR was 0.854±0.037 (p<0.0001; sensitivity=64%, specificity=96% at 0.78), and for iFR it was 0.816±0.043 (p<0.0001;sensitivity=62%, specificity=96% at 0.83)., Conclusions: Hyperaemic icECG ST-segment shift detects structurally relevant coronary stenotic lesions with high sensitivity, while they are identified highly specific by FFR and iFR., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Introduction: The electrocardiogram (ECG) is a valuable diagnostic tool for the diagnosis of myocardial ischemia during acute coronary syndrome. Aside from the commonly used ST-segment shift indicative of ischemia, several other ECG parameters are pathophysiologically reasonable. Thus, the goal of this study was to assess the accuracy of different ischemia parameters as obtained by the highly susceptible intracoronary ECG (icECG)., Method: This was a retrospective observational study in 100 patients with chronic coronary syndrome. From each patient, a non-ischemic as well as ischemic icECG at the end of a one-minute proximal coronary balloon occlusion was available, and analysed twice by three different physicians, as well as once together for consensual results. The evaluated parameters were icECG ST-segment shift (mV), ST-integral (mV*sec), T-wave-integral (mV*sec), T-peak (mV), T-peak-to-end time (TPE; msec) and QTc-time (msec)., Results: All six icECG parameters showed significant differences between the non-ischemic and the ischemic recording. Using the icECG recording during coronary patency or occlusion as criterion for absent or present myocardial ischemia, ROC-analysis of icECG ST-segment shift showed an area under the curve (AUC) of 0.963 ± 0.029 (p < 0.0001). AUC for ST-integral was 0.899 ± 0.044 (p < 0.0001), for T-wave integral 0.791 ± 0.059 (p < 0.0001), for T-peak 0.811 ± 0.057 (p < 0.0001), for TPE 0.667 ± 0.068 (p < 0.0001), and for QTc-time 0.770 ± 0.061 (p < 0.0001). The best cut-off point for the detection of ischemia by icECG ST-segment shift was 0.365 mV (sensitivity 90%, specificity 95%)., Conclusion: When tested in a setting with artificially induced absolute myocardial ischemia, icECG ST-segment shift at a threshold of 0.365 mV most accurately distinguishes between absent and present ischemia., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

Natural, nonsurgical internal mammary artery (IMA) bypasses to the coronary circulation have been shown to function as extracardiac sources of myocardial blood supply. The goal of this randomized, placebo-controlled, double-blind trial was to test the efficacy of permanent right IMA (RIMA) device occlusion on right coronary artery (RCA) occlusive blood supply and on clinical and electrocardiographic (ECG) signs of myocardial ischemia., Methods: This was a prospective superiority trial in 100 patients with chronic coronary artery disease randomly allocated (1:1) to RIMA vascular device occlusion (verum group) or to RIMA sham procedure (placebo group). The primary study end point was RCA collateral flow index (CFI) as obtained during a 1-minute ostial RCA balloon occlusion at baseline before and at follow-up examination 6 weeks after the trial intervention. CFI is the ratio between simultaneous mean coronary occlusive divided by mean aortic pressure both subtracted by central venous pressure. Simultaneously obtained secondary study end points were the registration of angina pectoris and quantitative intracoronary ECG ST-segment shift., Results: CFI change during the follow-up period was +0.036 ± 0.068 in the verum group and -0.021 ± 0.097 in the placebo group (P = .0011). Angina pectoris during the same RCA balloon occlusions had disappeared at follow-up in 14/49 patients of the verum group and in 4/49 patients of the placebo group (P = .0091). Simultaneous intracoronary ECG ST-segment shift change revealed diminished myocardial ischemia at follow-up in the verum group and more severe ischemia in the placebo group., Conclusions: Permanent RIMA device occlusion augments RCA supply to the effect of diminishing clinical and electrocardiographic signs of myocardial ischemia during a brief controlled coronary occlusion., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Inferolateral early repolarization (ER) is associated with an increase in arrhythmic risk, particularly in the presence of myocardial ischemia., Objective: The purpose of this study was to determine the effect of myocardial ischemia on ER., Methods: We retrospectively analyzed procedural electrocardiograms (ECGs) of patients with ER undergoing a controlled, 1-minute coronary balloon occlusion for collateral function testing. ECG leads with ER were analyzed immediately before coronary balloon occlusion (PRE), at 60 seconds of coronary balloon occlusion (OCCL), and >30 seconds after balloon deflation., Results: Seventy-seven patients with ER in the preprocedural ECG (86% inferior, 20% lateral) underwent 135 coronary balloon occlusions during which a J wave was recorded in 224 leads (ER leads). From PRE to OCCL, ST-segment amplitude (ST) in the ER lead increased in 94 cases (44%) from 0.00 ± 0.03 to 0.05 ± 0.06 mV (P < .0001). In this group, J-wave amplitude (JWA) increased from 0.10 ± 0.07 to 0.13 ± 0.09 mV (P < .0001). ST in the ER lead decreased or was unchanged in 121 cases (56%) from PRE to OCCL (from 0.01 ± 0.05 to -0.02 ± 0.04 mV; P < .0001). In this group, JWA decreased from 0.10 ± 0.05 to 0.08 ± 0.07 mV (P < .0001). The change in JWA was related to the change in ST (linear regression analysis; R 2 = 0.34; P < .0001), while there was no relation between the change in R-wave amplitude and the change in ST (R 2 = 0.0003; P = .83)., Conclusion: During acute ischemia, JWA mirrors ST-segment changes. This may explain increased arrhythmic vulnerability of patients with ER during myocardial ischemia. It also adds weight to the hypothesis of ER being a phenomenon of repolarization., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Objectives: This study sought to validate European Society of Cardiology guideline-endorsed high-risk features of stent-related recurrent ischemic events for the prediction of ischemic and bleeding outcomes including a stratification according to the PRECISE-DAPT score estimated bleeding risk., Background: The 2017 European Society of Cardiology-focused update on dual-antiplatelet therapy endorsed high-risk features of stent-related recurrent ischemic events. Because patients with high ischemic risk also have an increased bleeding risk, appropriate risk stratification for ischemic and bleeding events is crucial., Methods: Between January 2009 and December 2015, a total of 10,236 consecutive patients undergoing clinically indicated percutaneous coronary intervention were prospectively included in the Bern PCI Registry. Guideline-endorsed high-risk features were retrospectively assessed. The primary ischemic endpoint was device-oriented composite endpoint (DOCE) (cardiac death, target-vessel myocardial infarction, and target lesion revascularization) at 1 year, and the primary bleeding endpoint was Bleeding Academic Research Consortium (BARC) 3-5 at 1 year., Results: A total of 5,323 (52.0%) patients had at least 1 high-risk feature. Among patients with high-risk features, DOCE (12.3% vs. 5.5%; p < 0.001) and BARC 3-5 bleeding (4.9% vs. 2.2%; p < 0.001) occurred more frequently compared with those without. There was a graded risk increase for DOCE (0: 5.5%; 1 to 2: 11.3%; and ≥3: 16.7%; p < 0.001) and BARC 3-5 bleeding (0: 2.2%; 1 to 2: 4.5%; and ≥3: 6.6%; p < 0.001) as the number of high-risk features increased. High-PRECISE-DAPT score (≥25) was associated with an increased risk of DOCE and BARC 3-5 bleeding, irrespective of number of high-risk features., Conclusions: The European Society of Cardiology guideline-endorsed high-risk features were associated with increased ischemic and bleeding risks following percutaneous coronary intervention in routine clinical practice. (CARDIOBASE Bern PCI Registry; NCT02241291)., (Copyright © 2019 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objective: To test the effect of long-term pegfilgrastim on collateral function and myocardial ischaemia in patients with chronic stable coronary artery disease (CAD)., Methods: This was a prospective clinical trial with randomized 2:1 allocation to pegfilgrastim or placebo for 6 months. The primary study endpoint was collateral flow index (CFI) as obtained during a 1-minute ostial coronary artery balloon occlusion. CFI is the ratio of mean coronary occlusive divided by mean aortic pressure both subtracted by central venous pressure (mm Hg/mm Hg). Secondary endpoints were signs of myocardial ischaemia determined during the same coronary occlusion, that is quantitative intracoronary (i.c.) ECG ST-segment shift (mV) and the occurrence of angina pectoris. Endpoints were obtained at baseline before and at follow-up after three subcutaneous study drug injections., Results: Collateral flow index in the pegfilgrastim group changed from 0.096 ± 0.076 at baseline to 0.126 ± 0.070 at follow-up (P = 0.0039), while in the placebo group CFI changed from 0.157 ± 0.146 to 0.122 ± 0.043, respectively (P = 0.29); the CFI increment at follow-up was +0.030 ± 0.075 in the pegfilgrastim group and -0.034 ± 0.148 in the placebo group (P = 0.0172). In the pegfilgrastim group, i.c. ECG ST-segment shift changed from +1.23 ± 1.01 mV at baseline to +0.93 ± 0.97 mV at follow-up (P = 0.0049), and in the placebo group, it changed from +0.98 ± 1.02 mV to +1.43 ± 1.09 mV, respectively (P = 0.05). At follow-up, the fraction of patients free from angina pectoris during coronary occlusion had increased in the pegfilgrastim but not in the placebo group., Conclusion: Pegfilgrastim given over the course of 6 months improves collateral function in chronic stable CAD, which is reflected by reduced myocardial ischaemia during a controlled coronary occlusion., (© 2018 Stichting European Society for Clinical Investigation Journal Foundation.)

Background: The function of naturally existing internal mammary (IMA)-to-coronary artery bypasses and their quantitative effect on myocardial ischemia are unknown., Methods and Results: The primary end point of this study was collateral flow index (CFI) obtained during two 1-minute coronary artery balloon occlusions, the first with and the second without simultaneous distal IMA occlusion. The secondary study end point was the quantitatively determined intracoronary ECG ST-segment elevation. CFI is the ratio of simultaneously recorded mean coronary occlusive pressure divided by mean aortic pressure both subtracted by mean central venous pressure. A total of 180 pairs of CFI measurements were performed among 120 patients. With and without IMA occlusion, CFI was 0.110±0.074 and 0.096±0.072, respectively (P<0.0001). The difference of CFI obtained in the presence minus CFI obtained in the absence of IMA occlusion was highest and most consistently positive during left IMA with left anterior descending artery occlusion and during right IMA with right coronary artery occlusion (ipsilateral occlusions): 0.033±0.044 and 0.025±0.027, respectively. This CFI difference was absent during right IMA with left anterior descending artery occlusion and during left IMA with right coronary artery occlusion (contralateral occlusions): -0.007±0.034 and 0.001±0.023, respectively (P=0.0002 versus ipsilateral occlusions). The respective CFI differences during either IMA with left circumflex artery occlusion were inconsistently positive. Intracoronary ECG ST-segment elevations were significantly reduced during ipsilateral IMA occlusions but not during contralateral or left circumflex artery occlusions., Conclusion: There is a functional, ischemia-reducing extracardiac coronary artery supply via ipsilateral but not via contralateral natural IMA bypasses., Clinical Trial Registration Url: http://www.clinicaltrials.gov. Unique identifier: NCTO1676207., (© 2014 American Heart Association, Inc.)

Objective: This study tested the hypotheses that intermittent coronary sinus occlusion (iCSO) reduces myocardial ischaemia, and that the amount of ischaemia reduction is related to coronary collateral function., Design: Prospective case-control study with intraindividual comparison of myocardial ischaemia during two 2-min coronary artery balloon occlusions with and without simultaneous iCSO by a balloon-tipped catheter., Setting: University Hospital., Patients: 35 patients with chronic stable coronary artery disease., Intervention: 2-min iCSO., Main Outcome Measures: Myocardial ischaemia as assessed by intracoronary (i.c.) ECG ST shift at 2 min of coronary artery balloon occlusion. Collateral flow index (CFI) without iCSO, that is, the ratio between mean distal coronary occlusive (Poccl) and mean aortic pressure (Pao) both minus central venous pressure., Results: I.c. ECG ST segment shift (elevation in all) at the end of the procedure with iCSO versus without iCSO was 1.33±1.25 mV versus 1.85±1.45 mV, p<0.0001. Regression analysis showed that the degree of i.c. ECG ST shift reduction during iCSO was related to CFI, best fitting a Lorentzian function (r(2)=0.61). Ischaemia reduction with iCSO was greatest at a CFI of 0.05-0.20, whereas in the low and high CFI range the effect of iCSO was absent., Conclusions: ICSO reduces myocardial ischaemia in patients with chronic coronary artery disease. Ischaemia reduction by iCSO depends on coronary collateral function. A minimal degree of collateral function is necessary to render iCSO effective. ICSO cannot manifest an effect when collateral function prevents ischaemia in the first place.

Aims: Late acquired incomplete stent apposition (ISA) is more common after drug-eluting stent (DES) than bare metal stent (BMS) implantation and has been associated with vascular hypersensitivity and stent thrombosis (ST). We investigated the impact of incidentally discovered ISA as assessed by intravascular ultrasound (IVUS) 8 months after DES implantation on the long-term clinical outcome., Methods and Results: A total of 194 patients with 221 lesions were prospectively followed through 5 years. At 8 months, IVUS showed evidence of ISA among 37 patients with 39 lesions (18%) (mean ISA(max) 4.7 ± 5.0 mm(2)), whereas no ISA was observed among 157 patients with 182 lesions. Incomplete stent apposition was more prevalent among segments treated with sirolimus-eluting (n = 103) than paclitaxel-eluting stents (n = 118) (27 vs. 9%, P = 0.001). Between IVUS investigation at the 8-month and 5-year follow-up, major adverse cardiac events occurred more frequently in patients with (18.9%, n = 7) than without ISA (7.0%, n = 11) (HR = 2.71, 95% CI: 1.05-6.96, P = 0.031). While there were no differences with respect to death, the rate of myocardial infarction was higher among patients with (13.5%, n = 5) than without ISA (1.9%, n = 3) (HR = 7.53, 95% CI: 1.79-31.6, P = 0.001). Very late ST was more common among patients with than without ISA [Academic Research Consortium-definite ST:13.5% (n = 5) vs. 0.6% (n = 1) HR = 23.2, 95% CI: 2.65-203, P < 0.001]., Conclusion: In the present study, the presence of ISA as assessed by IVUS 8 months after DES implantation was associated with a higher rate of myocardial infarction and very late stent thrombosis during long-term follow-up. The prognostic impact of ISA on long-term clinical outcomes requires further investigation.

Background: Although rare, iatrogenic left main coronary artery (LM) dissection is a feared complication of coronary catheterization. Its incidence, optimal therapeutic management, and prognosis remain largely unknown. The aim of the present study was to estimate the incidence, characterize the population at risk, depict the initial management, and evaluate the long-term prognosis of iatrogenic LM dissection., Methods: Thirty-eight patients who fulfilled the National Heart, Lung, and Blood Institute diagnostic criteria for iatrogenic LM dissection were retrieved from our database and followed up by telephone or physician visit. The primary end point was freedom from major adverse cardiac events (MACE) at 5 years., Results: The overall incidence of iatrogenic LM dissection during the study period was 0.07% (38/51,452 patients) and almost twice as common with percutaneous coronary intervention than coronary angiography. From 38 patients, 1 (3%) patient died before any therapeutic attempt was performed, 6 (16%) patients were treated conservatively, and 31 (82%) patients underwent stent implantation and/or coronary artery bypass grafting (CABG). In-hospital outcome was favorable irrespective of the therapeutic strategy. During the 5-year follow-up, among 31 patients who underwent revascularization treatment by stenting or CABG, one patient died in each group from a cardiac cause, and MACE were observed in 12 patients (39%). Kaplan-Meier cumulative survival estimates showed no significant difference between different revascularization treatment strategies., Conclusions: Iatrogenic LM dissection is a rare complication of cardiac catheterization procedures with favorable early and long-term outcome when recognized timely and managed properly., (Copyright 2010 Mosby, Inc. All rights reserved.)

Infarct size (IS) increases with vascular occlusion time, area at risk for infarction, lack of collateral supply, absence of preconditioning, and myocardial demand for O2 supply. ECG S-T segment elevation is used as a measure of severity of ischemia and a surrogate for IS. This study in 50 patients with coronary artery disease undergoing a first 120-s balloon occlusion of a stenosis sought to determine whether S-T segment elevation, corrected for the above-mentioned variables, in the left coronary artery (LCA group, n = 36) is different from that in the right coronary artery (RCA group, n = 14) territory. After consideration of all known determinants of IS, particularly mass at risk and collateral supply, the LCA territory is more sensitive than the RCA region to a 2-min period of myocardial ischemia.

Background: Evidence for the proper management of ischemic heart disease (IHD) in the general population is well established, but recommendations for physical activity and competitive sports in these patients are scarce. The aim of the present paper was to provide such recommendations to complement existing ESC and international guidelines on rehabilitation and primary/secondary prevention., Design and Methods: Due to the lack of studies in this field, the current recommendations are the result of consensus among experts. Sports are classified into low/moderate/high dynamic and low/moderate/high static, respectively., Results: Patients with a definitive IHD and higher probability of cardiac events are not eligible for competitive sports (CS) but for individually designed leisure time physical activity (LPA); patients with definitive IHD and lower probability of cardiac events as well as those with no IHD but with a positive exercise test and high risk profile (SCORE > 5%) are eligible for low/moderate static and low dynamic (IA-IIA) sports and individually designed LPA. Patients without IHD and a high risk profile+ a negative exercise-test and those with a low risk profile (SCORE < 5%) are allowed all LPA and competitive sports with a few exceptions., Conclusions: Individually designed LPA is possible and encouraged in patients with and without established IHD. Competitive sports may be restricted for patients with IHD, depending on the probability of cardiac events and the demands of the sport according to the current classification.

Fractional flow reserve (FFR) measurements are recommended for assessing hemodynamic coronary stenosis severity. Intracoronary ECG (icECG) is easily obtainable and highly sensitive in detecting myocardial ischemia due to its close vicinity to the myocardium. We hypothesized that the remission time of myocardial ischemia on icECG after a controlled coronary occlusion accurately detects hemodynamically relevant coronary stenosis. This retrospective, observational study included patients with chronic coronary syndrome undergoing hemodynamic coronary stenosis assessment immediately following a strictly 1-min proximal coronary artery balloon occlusion with simultaneous icECG recording. icECG was used for a beat-to-beat analysis of the ST-segment shift during reactive hyperemia immediately following balloon deflation. The time from coronary balloon deflation until the ST-segment shift reached 37% of its maximum level, i.e., icECG ST-segment shift remission time (τ-icECG in seconds), was obtained by an automatic algorithm. τ-icECG was tested against the simultaneously obtained reactive hyperemia FFR at a threshold of 0.80 as a reference parameter. From 120 patients, 139 icECGs (age, 68 ± 10 yr old) were analyzed. Receiver operating characteristic (ROC) analysis of τ-icECG for the detection of hemodynamically relevant coronary stenosis at an FFR of ≤0.80 was performed. The area under the ROC curve was equal to 0.621 (P = 0.0363) at an optimal τ-icECG threshold of 8 s (sensitivity, 61%; specificity, 67%). τ-icECG correlated inversely and linearly with FFR (P = 0.0327). This first proof-of-concept study demonstrates that τ-icECG, a measure of icECG ST segment-shift remission after a 1-min coronary artery balloon occlusion accurately detects hemodynamically relevant coronary artery stenosis according to FFR at a threshold of ≥8 s. NEW & NOTEWORTHY: Invasive hemodynamic measurements are recommended by the current cardiology guidelines to guide percutaneous coronary interventions in the setting of chronic coronary syndrome. However, those pressure-derived indices demonstrate several theoretical and practical limitations. Thus, this study demonstrates the accuracy of a novel, pathophysiology-driven approach using intracoronary ECG for the identification of hemodynamically relevant coronary lesions by quantitatively assessing myocardial ischemia remission. [ABSTRACT FROM AUTHOR]

Background--The objective of this study is to test the effect of permanent right internal mammary artery device closure on coronary collateral function and myocardial ischemia. Methods and Results--This was a prospective, open-label clinical trial in 50 patients with coronary artery disease. The primary study end point was coronary collateral flow index as obtained during a 1-minute proximal right coronary artery (RCA) and left coronary artery balloon occlusion at baseline before and at follow-up examination 6 weeks after distal right internal mammary artery device closure. Collateral flow index is the ratio between simultaneously recorded mean coronary occlusive pressure divided by mean aortic pressure, both subtracted by central venous pressure. Secondary study end points were fractional flow reserve during vessel patency, the quantitative intracoronary ECG ST-segment elevation, and angina pectoris during the same 1-minute coronary occlusion. Collateral flow index in the untreated RCA and left coronary artery changed from 0.071±0.082 at baseline to 0.132±0.117 (P<0.0001) at follow-up examination and from 0.106±0.092 to 0.081±0.079 (P=0.29), respectively. RCA fractional flow reserve increased significantly (P=0.0029) from baseline to follow-up examination, despite deferral of coronary intervention in all patients. There was a decrease in intracoronary ECG ST-elevation during RCA occlusion from baseline to follow-up examination (P=0.0015); it did not change in the left coronary artery. Angina pectoris during RCA occlusion tended to occur in fewer patients at follow-up versus baseline examination (P=0.06). Conclusions--Permanent right internal mammary artery device closure seems to augment extracardiac ipsilateral coronary supply to the effect of reducing ischemia in the dependent myocardial region. [ABSTRACT FROM AUTHOR]

Many people with acute myocardial infarction die from sudden cardiac arrest before reaching the hospital. The current clinical understanding of the mechanisms and risk factors surrounding sudden cardiac death is limited. However, 2 factors related to sudden death, namely the occluded coronary vessel (right coronary, left circumflex, or left anterior descending artery) and the extent of collateral circulation, are of potential relevance. Recent data suggest that the risk differs between the different coronary arteries and that coronary collateral circulation seems to have an important protective 'antiarrhythmic' effect. This editorial will address possible mechanisms and potential implications in clinical practice. Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]