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Background: There is variability in clinical and lesion characteristics as well as techniques in chronic total occlusion (CTO) percutaneous coronary intervention (PCI)., Methods: We analyzed patient and lesion characteristics, techniques, and outcomes in 11 503 CTO-PCI procedures performed in North America (NA) and in the combined regions of Europe, Asia, and Africa from 2017 to 2023 as documented in the PROGRESS-CTO registry., Results: Eight thousand four hundred seventy-nine (74%) procedures were performed in NA. Compared with non-NA patients, NA patients were older, with higher body mass index and higher prevalence of diabetes, hypertension, dyslipidemia, family history of coronary artery disease, prior history of PCI, coronary artery bypass graft surgery and heart failure, cerebrovascular disease, and peripheral arterial disease. Their CTOs were more complex, with higher J-CTO (2.56 ± 1.22 vs 1.81 ± 1.24; P less than .001) and PROGRESS-CTO (1.29 ± 1.01 vs 1.07 ± 0.95; P less than .001) scores, longer length, and higher prevalence of proximal cap ambiguity, blunt/no stump, moderate to severe calcification, and proximal tortuosity. Retrograde (31.0% vs 22.1%; P less than .001) and antegrade dissection and re-entry (ADR) (21.2% vs 9.2%; P less than .001) were more commonly used in NA centers, along with intravascular ultrasound (69.0% vs 10.1%; P less than .001). Procedure and fluoroscopy times were longer in NA, while contrast volume and radiation dose were lower. Technical (86.7% vs 86.8%; P > .90) and procedural (85.4% vs 85.8%; P = .70) success and in-hospital major adverse cardiovascular events (MACE) (1.9% vs 1.7%; P = .40) were similar in NA and non-NA centers., Conclusions: Compared with non-NA patients, NA patients undergoing CTO PCI have more comorbidities, higher CTO lesion complexity, are more likely to undergo treatment with retrograde and ADR, and have similar technical success and MACE.

Background: There is limited data on retrograde chronic total occlusion (CTO) percutaneous coronary intervention (PCI) via ipsilateral epicardial collaterals (IEC)., Aims: To compare the clinical and angiographic characteristics, and outcomes of retrograde CTO PCI via IEC versus other collaterals in a large multicenter registry., Methods: Observational cohort study from the Prospective Global registry for the study of Chronic Total Occlusion Intervention (PROGRESS-CTO)., Results: Of 4466 retrograde cases performed between 2012 and 2023, crossing through IEC was attempted in 191 (4.3%) cases with 50% wiring success. The most common target vessel in the IEC group was the left circumflex (50%), in comparison to other retrograde cases, where the right coronary artery was most common (70%). The Japanese CTO score was similar between the two groups (3.13 ± 1.23 vs. 3.06 ± 1.06, p = 0.456); however, the IEC group had a higher Prospective Global Registry for the Study of Chronic Total Occlusion Intervention (PROGRESS-CTO) score (1.95 ± 1.02 vs. 1.27 ± 0.92, p < 0.0001). The most used IEC guidewire was the SUOH 03 (39%), and the most frequently used microcatheter was the Caravel (43%). Dual injection was less common in IEC cases (66% vs. 89%, p < 0.0001). Technical (76% vs. 79%, p = 0.317) and procedural success rates (74% vs. 79%, p = 0.281) were not different between the two groups. However, IEC cases had a higher procedural complications rate (25.8% vs. 16.4%, p = 0.0008), including perforations (17.3% vs. 9.0%, p = 0.0001), pericardiocentesis (3.1% vs. 1.2%, p = 0.018), and dissection/thrombus of the donor vessel (3.7% vs. 1.2%, p = 0.002)., Conclusion: The use of IEC for retrograde CTO PCI was associated with similar technical and procedural success rates when compared with other retrograde cases, but higher incidence of periprocedural complications., (© 2024 Wiley Periodicals LLC.)

Ranolazine is an anti-anginal medication given to patients with chronic angina and persistent symptoms despite medical therapy. We examined 11 491 chronic total occlusion (CTO) percutaneous coronary interventions (PCI) that were performed at 41 US and non-US centers between 2012 and 2023 in the PROGRESS-CTO Registry. Patients on ranolazine at baseline had more comorbidities, more complex lesions, lower procedural and technical success (based on univariable but not multivariable analysis), and higher incidence of major adverse cardiac events (MACE) (on both univariable and multivariable analysis).

Background: There is limited data on equipment loss or entrapment during chronic total occlusion (CTO) percutaneous coronary intervention (PCI)., Methods: We analyzed the baseline clinical and angiographic characteristics and outcomes of equipment loss/entrapment at 43 US and non-US centers between 2017 and 2023., Results: Equipment loss/entrapment was reported in 40 (0.4%) of 10 719 cases during the study period. These included guidewire entrapment/fracture (n = 21), microcatheter entrapment/fracture (n = 11), stent loss (n = 8) and balloon entrapment/fracture/rupture (n = 5). The equipment loss/entrapment cases were more likely to have moderate to severe calcification, longer lesion length, higher J-CTO and PROGRESS-CTO complications scores, and use of the retrograde approach compared with the remaining cases. Retrieval was attempted in 71.4% of the guidewire, 90.9% of the microcatheter, 100% of the stent loss, and 100% of the balloon cases, and was successful in 26.7%, 30.0%, 50%, and 40% of the cases, respectively. Procedures complicated by equipment loss/entrapment had higher procedure and fluoroscopy time, contrast volume and patient air kerma radiation dose, lower procedural (60.0% vs 85.6%, P less than .001) and technical (75.0% vs 86.8%, P = .05) success, and higher incidence of major adverse cardiac events (MACE) (17.5% vs 1.8%, P less than .001), acute MI (7.5% vs 0.4%, P less than .001), emergency coronary artery bypass graft (CABG) (2.5% vs 0.1%, P = .03), perforation (20.0% vs 4.9%, P less than .001), and death (7.5% vs 0.4%, P less than .001)., Conclusions: Equipment loss is a rare complication of CTO PCI; it is more common in complex CTOs and is associated with lower technical success and higher MACE.

Objectives: There is limited data on race and outcomes of chronic total occlusion (CTO) percutaneous coronary intervention (PCI). The authors sought to evaluate CTO PCI techniques and outcomes in different racial groups., Methods: We examined the baseline characteristics and procedural outcomes of 11 806 CTO PCIs performed at 44 US and non-US centers between 2012 and March 2023. In-hospital major adverse cardiac events (MACE) included death, myocardial infarction, repeat target-vessel revascularization, pericardiocentesis, cardiac surgery, and stroke prior to discharge., Results: The most common racial group was White (84.5%), followed by Black (5.7%), "Other" (3.9%), Hispanic (2.9%), Asian (2.4%), and Native American (0.7%). There were significant differences in the baseline characteristics between different racial groups. When compared with non-White patients, the retrograde approach and antegrade dissection re-entry were more likely to be the successful crossing strategies in White patients without any significant differences in technical success (86.4% vs 86.4%; P = .93), procedural success (84.8% vs 85.0%; P = .79), and in-hospital MACE (2.0% vs 1.5%; P = .15) between the 2 groups. The technical success rate was significantly higher in the "Other" racial group (91.0% vs 86.4% in White, 86.9% in Asian, 84.5% in Black, 84.5% in Hispanic, and 83.3% in Native American; P = .03) without any significant differences in procedural success or in-hospital MACE rates between the groups., Conclusions: Despite differences in baseline characteristics and procedural techniques, the procedural success and in-hospital MACE of CTO PCI were not significantly different between most racial groups.

Background: The optimal range of activated clotting time (ACT) in chronic total occlusion (CTO) percutaneous coronary intervention (PCI) has received limited study., Methods: We examined the association between ACT and in-hospital ischemic and bleeding outcomes in patients who underwent CTO PCI in the Prospective Global Registry for the Study of CTO Intervention., Results: ACT values were available for 4377 patients who underwent CTO PCI between 2012 and 2023 at 29 centers. The mean ACT distribution was less than 250 seconds (19%), 250 to 349 seconds (50%), and greater than or equal to 350 seconds (31%). The incidence of ischemic events, bleeding events, and net adverse cardiovascular events (NACE) was 0.8%, 3.0%, and 3.8%, respectively. In multiple logistic regression analysis, increasing nadir ACT was associated with decreasing ischemic events (adjusted odds ratio [aOR] per 50-second increments: 0.69 [95% confidence interval (CI), 0.50-0.94; P=.017]; and increasing peak ACT was associated with increasing bleeding events (aOR per 50-second increments: 1.17 [95% CI ,1.01-1.36; P=.032]). A U-shaped association was seen between mean ACT and NACE, where restricted cubic spline analysis demonstrated that patients with a low ( less than 200 seconds) or high ( greater than 400 seconds) ACT had increasing NACE risk compared with an ACT of 200 to 400 seconds (aOR 2.06, 95% CI 1.18-3.62; P=.012)., Conclusions: Among patients who underwent CTO PCI, mean ACT had a U-shaped relationship with NACE, where patients with a low ( less than 200 seconds) ACT (driven by ischemic events) or high ( greater than 400 seconds) ACT (driven by bleeding) had higher NACE compared with an ACT of 200 to 400 seconds.

Background: Retrograde chronic total occlusion (CTO) percutaneous coronary intervention (PCI) is associated with lower success and higher complication rates when compared with the antegrade approach., Objectives: This study sought to assess contemporary techniques and outcomes of retrograde CTO PCI., Methods: We examined the baseline characteristics, procedural techniques and outcomes of 4,058 retrograde CTO PCIs performed at 44 centers between 2012 and 2023. Major adverse cardiac events (MACE) included any of the following in-hospital events: death, myocardial infarction, repeat target vessel revascularization, pericardiocentesis, cardiac surgery, and stroke., Results: The average J-CTO (Multicenter CTO Registry in Japan) score was 3.1 ± 1.1. Retrograde crossing was successful in 60.5% and lesion crossing in 81.6% of cases. The collaterals pathways successfully used were septals in 62.0%, saphenous vein grafts in 17.4%, and epicardials in 19.1%. The technical and procedural success rates were 78.7% and 76.6%, respectively. When retrograde crossing failed, technical success was achieved in 50.3% of cases using the antegrade approach. In-hospital MACE was 3.5%. The clinical coronary perforation rate was 5.8%. The incidence of in-hospital MACE with retrograde true lumen crossing, just marker antegrade crossing, conventional reverse controlled antegrade and retrograde tracking (CART), contemporary reverse CART, extended reverse CART, guide-extension reverse CART, and CART was 2.1%, 0.8%, 5.5%, 3.0%, 2.1%, 3.2%, and 4.1%, respectively; P = 0.01)., Conclusions: Retrograde CTO PCI is utilized in highly complex cases and yields moderate success rates with 5.8% perforation and 3.5% periprocedural MACE rates. Among retrograde crossing strategies, retrograde true lumen puncture was the safest. There is need for improvement of the efficacy and safety of retrograde CTO PCI., Competing Interests: Funding Support and Author Disclosures The Minneapolis Heart Institute Foundation; Science Center for Coronary Artery Disease (CCAD) helped support this research project. Study data were collected and managed using Research Electronic Data Capture. (REDCap) electronic data capture tools hosted at the Minneapolis Heart Institute Foundation (MHIF), Minneapolis, Minnesota. Dr Allana has been a consultant for Boston Scientific and Abiomed. D. Choi has received speaking honoraria from Shockwave. Dr Alaswad has been a consultant and speaker for Boston Scientific, Abbott Cardiovascular, Teleflex, and Cardiovascular Systems Inc. Dr Davies has received speaking honoraria from Abiomed, Asahi Intec, Boston Scientific, Medtronic, Siemens Healthineers, Shockwave, and Teleflex; and has served on advisory boards for Abiomed, Boston Scientific, Medtronic, and Rampart. Dr Karmpaliotis has received honoraria from Boston Scientific, Abbott Vascular, Abiomed; Equity: Saranas, Soundbite, and Traverse Vascular. Dr Jaffer has received research funding from Canon, Siemens, Shockwave, Teleflex, Mercator, Boston Scientific, HeartFlow, and Amarin; has been a consultant for Boston Scientific, Siemens, Magenta Medical, International Medical Device Solutions, Asahi Intecc, Biotronik, Philips, Intravascular Imaging, and DurVena; holds equity interest in Intravascular Imaging Inc, Massachusetts General Hospital, and DurVena; and has licensing arrangements with Terumo, Canon, and Spectrawave, for which he hast he right to receive royalties. Dr Khatri has received honoraria for proctoring and speaking from Abbott Vascular, Medtronic, Terumo, and Shockwave Medical. Dr Poommipanit has been a consultant for Medtronic, Asahi Intecc, and Abbott Vascular. Dr Azzalini has received consulting fees from Teleflex, Abiomed, GE Healthcare, Asahi Intecc, Philips, Abbott Vascular, Reflow Medical, and Cardiovascular Systems, Inc. Dr Nicholson has been a proctor and is on Speakers Bureau and advisory boards for Abbott Vascular, Boston Scientific, and Asahi Intecc; and holds intellectual property with Vascular Solutions. Dr Jaber has received consulting fees from Inari Medical and Medtronic. Dr Rinfret has been a consultant for Boston Scientific, Teleflex, Medtronic, Abbott, and Abiomed. Dr Brilakis has received consulting/speaker honoraria from Abbott Vascular, American Heart Association (as associate editor of Circulation), Amgen, Asahi Intecc, Biotronik, Boston Scientific, Cardiovascular Innovations Foundation (board of directors), ControlRad, CSI, Elsevier, GE Healthcare, IMDS, InfraRedx, Medicure, Medtronic, Opsens, Siemens, and Teleflex; has received research support from Boston Scientific and GE Healthcare; is the owner of Hippocrates LLC; and is a shareholder in MHI Ventures, Cleerly Health, and Stallion Medical. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

We examined the outcomes of the Carlino technique in chronic total occlusion (CTO) percutaneous coronary interventions (PCIs). We analyzed the baseline clinical and angiographic characteristics and outcomes of 128 CTO PCIs that included the Carlino technique at 22 US and no-US centers between 2016 and 2023. The Carlino technique was used in 128 (2.8%) of 4,508 cases that used anterograde dissection and reentry (78.9%) or the retrograde approach (21.1%) during the study period, and it increased steadily over time (from 0.0% in 2016 to 8.3% in 2023). The mean patient age was 65.6 ± 9.7 years, and 88.7% of the patients were men with high prevalence of hypertension (89.1%) and dyslipidemia (80.2%). The Carlino technique was more commonly used in cases with moderate to severe calcification (77.2% vs 55.5%, p <0.001) with higher J-CTO (3.3 ± 0.9 vs 3.0 ± 1.1, p = 0.007), Prospective Global Registry for the Study of Chronic Total Occlusion Intervention (PROGRESS-CTO) (1.7 ± 1.0 vs 1.4 ± 1.0, p = 0.001), PROGRESS-CTO Mortality (2.6 ± 0.9 vs 2.0 ± 0.9, p = 0.013) and PROGRESS-CTO Perforation (3.7 ± 1.1 vs 3.5 ± 1.0, p = 0.029) scores. Carlino cases had longer procedure and fluoroscopy time, and higher contrast volume and radiation dose. Carlino cases had lower technical (65.6% vs 78.5%, p <0.001) and procedural (63.3% vs 76.3%, p <0.001) success, similar major adverse cardiac events (6.2% vs 3.2%, p = 0.101) and higher incidence of pericardiocentesis (3.9% vs 1.3%, p = 0.042), perforation (18.0% vs 8.9%, p = 0.001) and contrast-induced acute kidney injury (2.3% vs 0.4%, p = 0.012). The Carlino technique was associated with higher procedural success when used for retrograde crossing (81.5% vs 58.4%, p = 0.047). The Carlino technique is increasingly being used in CTO PCI especially for higher complexity lesions., Competing Interests: Declaration of Competing Interest The authors have no competing interests to declare., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Intravascular lithotripsy (IVL) safely and effectively modifies calcified coronary lesions during percutaneous coronary interventions (PCI). Data regarding its utility in modifying calcified left main coronary artery (LMCA) disease are limited. This study aimed to evaluate short-term outcomes of IVL-assisted LMCA PCI., Methods: This retrospective multicenter all-comers study analyzed patients who underwent intravascular imaging-guided, IVL-assisted PCI for calcified LMCA disease. Clinical and procedural characteristics were obtained, including intravascular imaging measurements. Technical success was defined as successful stent deployment with <30% residual diameter stenosis. Major adverse cardiac events (MACE) was a composite of all-cause death, myocardial infarction, and target vessel revascularization evaluated immediately postprocedure and at 30-day follow-up., Results: Among 184 patients treated at 7 centers from 2019-2023, IVL-assisted LMCA PCI achieved 99.4% technical success. Calcium fracture was identified in 136/165 cases (82.4%) on post-IVL imaging. Pretreatment minimal luminal area increased significantly compared to post-PCI minimal stent area (MSA) (4.1 ± 1.3 to 9.3 ± 2.5 mm 2 , respectively; P < .001). There was a direct correlation between IVL balloon size and the final MSA ( P = .002). In-hospital MACE was 4.4% and 30-day MACE was 8.8%. In multivariate logistic regression, presentation with troponin-positive myocardial infarction was the sole predictor of 30-day MACE., Conclusions: IVL-assisted PCI for calcified LMCA lesions was safe and resulted in high technical success rates, confirming its utility as an effective treatment in this challenging lesion subset., (© 2023 The Author(s).)

Background: Coronary calcification is common and increases the difficulty of chronic total occlusion (CTO) percutaneous coronary intervention (PCI)., Methods: We examined the impact of calcium on procedural outcomes of 13,079 CTO PCIs performed in 12,799 patients at 46 US and non-US centers between 2012 and 2023., Results: Moderate or severe calcification was present in 46.6% of CTO lesions. Patients whose lesions were calcified were older and more likely to have had prior coronary artery bypass graft surgery. Calcified lesions were more complex with higher J-CTO score (3.0 ± 1.1 vs. 1.9 ± 1.2; p < 0.001) and lower technical (83.0% vs. 89.9%; p < 0.001) and procedural (81.0% vs. 89.1%; p < 0.001) success rates compared with mildly calcified or non-calcified CTO lesions. The retrograde approach was more commonly used among cases with moderate/severe calcification (40.3% vs. 23.5%; p < 0.001). Balloon angioplasty (76.6%) was the most common lesion preparation technique for calcified lesions, followed by rotational atherectomy (7.3%), laser atherectomy (3.4%) and, intravascular lithotripsy (3.4%). The incidence of major adverse cardiovascular events (MACE) was higher in cases with moderate or severe calcification (3.0% vs. 1.2%; p < 0.001), as was the incidence of perforation (6.5% vs. 3.4%; p < 0.001). On multivariable analysis, the presence of moderate/severe calcification was independently associated with lower technical success (odds ratio, OR = 0.73, 95% CI: 0.63-0.84) and higher MACE (OR = 2.33, 95% CI: 1.66-3.27)., Conclusions: Moderate/severe calcification was present in nearly half of CTO lesions, and was associated with higher utilization of the retrograde approach, lower technical and procedural success rates, and higher incidence of in-hospital MACE., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background: The impact of preprocedural anemia on the outcomes of chronic total occlusion (CTO) percutaneous coronary intervention (PCI) has received limited study., Methods: We examined the clinical and angiographic characteristics and procedural outcomes of 8633 CTO PCIs performed at 39 US and non-US centers between 2012 and 2023. Anemia was defined as a hemoglobin level of <13 g/dL in men and <12 g/dL in women., Results: Anemia was present in 1652 (19%) patients undergoing CTO PCI. Anemic patients had a higher incidence of comorbidities, such as diabetes mellitus, hypertension, dyslipidemia, heart failure, cerebrovascular disease, and peripheral arterial disease. CTOs in anemic patients were more likely to have complex angiographic characteristics, including smaller diameter, longer length, moderate to severe calcification, and moderate to severe proximal tortuosity. Anemic patients required longer procedure (119 vs. 107 min; p < 0.001) and fluoroscopy (45 vs. 40 min; p < 0.001) times but received similar contrast volumes. Technical success was similar between the two groups. In-hospital major adverse cardiac events (MACE) rates were higher in patients with anemia; however, this association was no longer significant after adjusting for confounding factors. Baseline anemia was independently associated with follow-up MACE (adjusted hazard ratio [HR]: 1.63; 95% confidence interval [CI]: 1.07-2.49; p = 0.023) and all-cause mortality (adjusted HR: 3.03; 95% CI: 1.41-6.49; p = 0.004)., Conclusions: Preprocedural anemia is associated with more comorbidities, higher lesion complexity, longer procedure times, and higher follow-up MACE and mortality after CTO PCI., (© 2023 Wiley Periodicals LLC.)

Background: There is limited information on the impact of the target vessel on the procedural techniques and outcomes of chronic total occlusion (CTO) percutaneous coronary intervention (PCI)., Methods: We analyzed the baseline clinical and angiographic characteristics and procedural outcomes of 11,580 CTO PCIs performed between 2012 and 2022 at 44 centers., Results: The most common CTO target vessel was the right coronary artery (RCA) (53.1%) followed by the left anterior descending artery (LAD) (26.0%) and the left circumflex artery (LCX) (19.8%). RCA CTOs were longer and more complex, with a higher Japanese CTO score compared with LAD or LCX CTOs. Technical success was higher among LAD (88.8%) lesions when compared with RCA (85.7%) or LCX (85.8%) lesions (P less than .001). The incidence of major adverse cardiovascular events (MACE) was overall 1.9% (n = 220) and was similar among target vessels (P=.916). There was a tendency toward more frequent utilization of the retrograde approach for more proximal occlusions in all 3 target vessels. When compared with all other RCA lesions combined, distal RCA lesions had higher technical success (87.7% vs 85.3%; P=.048). Technical success was similar between various locations of LAD CTOs (P=.704). First/second/third obtuse marginal branch had lower technical success when compared with all other LCX lesion locations (82.7% vs 86.8%; P=.014). There was no association between MACE and CTO location in all 3 target vessels., Conclusions: LAD CTO PCIs had higher technical and procedural success rates among target vessels. The incidence of MACE was similar among target vessels and among various locations within the target vessel.

Ischaemic papillary muscle rupture causing acute severe mitral regurgitation (MR) has a dramatic presentation and a very high mortality. Emergent surgical repair improves outcomes, which necessitates robust preoperative stabilisation. Here we discuss a patient with cardiogenic shock with an acute severe MR that was deemed very high risk for emergent valve replacement due to haemodynamic instability and respiratory failure. A percutaneous left ventricular assist device Impella 2.5 (Abiomed, Danvers, MA) drastically improved clinical status, and the patient underwent a successful surgical mitral valve replacement soon after placement of the temporary assist device. Our case highlights that percutaneous ventricular assist devices may help to stabilise patients with severe acute ischaemic MR, and it can serve as a bridge to surgery in high risk patients., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Importance: Several attempts have been made at developing models to predict 30-day readmissions in patients with heart failure, but none have sufficient discriminatory capacity for clinical use. Machine-learning (ML) algorithms represent a novel approach and may have potential advantages over traditional statistical modeling., Objective: To develop models using a ML approach to predict all-cause readmissions 30 days after discharge from a heart failure hospitalization and to compare ML model performance with models developed using "conventional" statistically based methods., Design, Setting, and Participants: Models were developed using ML algorithms, specifically, a tree-augmented naive Bayesian network, a random forest algorithm, and a gradient-boosted model and compared with traditional statistical methods using 2 independently derived logistic regression models (a de novo model and an a priori model developed using electronic health records) and a least absolute shrinkage and selection operator method. The study sample was randomly divided into training (70%) and validation (30%) sets to develop and test model performance. This was a registry-based study, and the study sample was obtained by linking patients from the Get With the Guidelines Heart Failure registry with Medicare data. After applying appropriate inclusion and exclusion criteria, 56 477 patients were included in our analysis. The study was conducted between January 4, 2005, and December 1, 2010, and analysis of the data was conducted between November 25, 2014, and June 30, 2016., Main Outcomes and Measures: C statistics were used for comparison of discriminatory capacity across models in the validation sample., Results: The overall 30-day rehospitalization rate was 21.2% (11 959 of 56 477 patients). For the tree-augmented naive Bayesian network, random forest, gradient-boosted, logistic regression, and least absolute shrinkage and selection operator models, C statistics for the validation sets were similar: 0.618, 0.607, 0.614, 0.624, and 0.618, respectively. Applying the previously validated electronic health records model to our study sample yielded a C statistic of 0.589 for the validation set., Conclusions and Relevance: Use of a number of ML algorithms did not improve prediction of 30-day heart failure readmissions compared with more traditional prediction models. Although there will likely be further applications of ML approaches in prognostic modeling, our study fits within the literature of limited predictive ability for heart failure readmissions.

A 91-year-old woman presented to the emergency department by ambulance after her family found her minimally responsive. Telemetry monitoring demonstrated episodes of non-sustained polymorphic ventricular tachycardia (PMVT) associated with significantly prolonged repolarization. Her medical history revealed that she was taking quinine or a derivative in three different forms: hydroxychloroquine, quinine sulfate (for leg cramps), and her gin mixed with tonic water (containing quinine). The present case is illustrative of classic etiologies and findings of acquired long QT syndrome, and serves as an important reminder for providers to take a complete medication history, including use of duplicative and alternative medicines and type of alcohol consumption., Competing Interests: The authors declare that they do not have a conflict of interest.