Determining the recurrence rate of premature ventricular complexes and idiopathic ventricular tachycardia after radiofrequency catheter ablation with the help of designing a machine-learning model.

Ventricular arrhythmias increase cardiovascular morbidity and mortality. Recurrent PVCs and IVT are generally considered benign in the absence of structural heart abnormalities. Artificial intelligence is a rapidly growing field. In recent years, medical professionals have shown great interest in the potential use of ML, an integral part of AI, in various disciplines, including diagnostic applications, decision-making, prognostic stratification, and solving complex pathophysiological aspects of diseases from these data at extraordinary complexity, scale, and acquisition rate. The aim of this study was to design an ML model to predict the probability of PVC and IVT recurrence after RF ablation. Data of patients were collected and manipulated using traditional analysis and various artificial intelligence models, namely MLP, Gradient Boosting Machines, Random Forest, and Logistic Regression. Hypertension, male sex, and the use of non-irrigate catheters were associated with less freedom from arrhythmia. All these results were obtained through traditional analytic methods, and according to AI, none of the variables had a clear effect on the recurrence of arrhythmia. Each AI model presents unique strengths and weaknesses, and further optimization and fine-tuning of these models are necessary to increase their clinical utility. By expanding the dataset, improved predictions can be fostered to ultimately increase the clinical utility of AI in predicting PVC erosion outcomes.

Risk scores for prediction of paroxysmal atrial fibrillation after acute ischemic stroke or transient ischemic attack: A systematic review and meta-analysis.

Introduction: Detection of paroxysmal atrial fibrillation (PAF) is crucial for secondary prevention in patients with recent strokes of unknown etiology. This systematic review and meta-analysis assess the predictive power of available risk scores for detecting new PAF after acute ischemic stroke (AIS). Methods: PubMed, Embase, Scopus, and Web of Science databases were searched until September 2023 to identify relevant studies. A bivariate random effects meta-analysis model pooled data on sensitivity, specificity, and area under the curve (AUC) for each score. The QUADAS-2 tool was used for the quality assessment. Results: Eventually, 21 studies with 18 original risk scores were identified. Age, left atrial enlargement, and NIHSS score were the most common predictive factors, respectively. Seven risk scores were meta-analyzed, with iPAB showing the highest pooled sensitivity and AUC (sensitivity: 89.4%, specificity: 74.2%, AUC: 0.83), and HAVOC having the highest pooled specificity (sensitivity: 46.3%, specificity: 82.0%, AUC: 0.82). Altogether, seven risk scores displayed good discriminatory power (AUC ≥0.80) with four of them (HAVOC, iPAB, Fujii, and MVP scores) being externally validated. Conclusion: Available risk scores demonstrate moderate to good predictive accuracy and can help identify patients who would benefit from extended cardiac monitoring after AIS. External validation is essential before widespread clinical adoption.

Trans-apical catheter ablation of ventricular tachycardia in a patient with metallic aortic and mitral valves.

We present a patient with a history of heart failure and metallic aortic and mitral valves surgeries, who required ablation for a drug-refractory left ventricular tachycardia. But the metallic valves prohibited the insertion of catheters via retrograde or via trans-septal approaches. Therefore, we decided to perform catheter ablation by direct left ventricle puncture through a minithoracotomy. The arrhythmia was successfully ablated via of trans-apical approach and did not recur at six months follow-up.

Brain MRI and EEG overemployment in patients with vasovagal syncope: results from a tertiary syncope unit.

BACKGROUND: The diagnosis of vasovagal syncope (VVS) is mainly based on history-taking and physical examination. However, brain Magnetic Resonance Imaging (MRI) and Electroencephalogram (EEG) are commonly used in the diagnostic course of VVS, despite not being indicated in the guidelines. This study aims to find the possible associated factors with the administration of brain MRI and EEG in patients with VVS. METHODS: Patients with a diagnosis of VVS from 2017 to 2022 were included. Several demographic and syncope features were recorded. The association of these was assessed with undergoing MRI, EEG, and either MRI or EEG. Univariate and multivariable logistic regression models were also used to calculate odds ratios (OR) and 95% confidence intervals (CI). RESULTS: A total of 1882 patients with VVS were analyzed, among which 810 underwent MRI (43.04%), 985 underwent EEG (52.34%), and 1166 underwent MRI or EEG (61.96%). Head trauma (OR 1.38, 95% CI 1.06 to 1.80), previous neurologist visit (OR 6.28, 95% CI 4.24 to 9.64), and gaze disturbance during syncope (OR 1.75, 95% CI 1.13 to 2.78) were all positively associated to the performance of brain MRI/EEG. Similar results were found for urinary incontinence (OR 2.415, 95% CI 1.494 to 4.055), amnesia (OR 1.421, 95% CI 1.053 to 1.930), headache after syncope (OR 1.321, 95% CI 1.046 to 1.672), and tonic-clonic movements in head-up tilt table test (OR 1.501, 95% CI 1.087 to 2.093). However, male sex (OR 0.655, 95% CI 0.535 to 0.800) and chest pain before syncope (OR 0.628, 95% CI 0.459 to 0.860) had significant negative associations with performing brain MRI/EEG. CONCLUSION: Based on our findings, performing MRI or EEG was common among VVS patients while it is not indicated in the majority of cases. This should be taken into consideration to prevent inappropriate MRI/EEG when there is a typical history compatible with VVS.

Effectiveness of conduction system pacing for cardiac resynchronization therapy: A systematic review and network meta-analysis.

INTRODUCTION: Cardiac resynchronization therapy (CRT) with biventricular pacing (BiV-CRT) is ineffective in approximately one-third of patients. CRT with Conduction system pacing (CSP-CRT) may achieve greater synchronization. We aimed to assess the effectiveness of CRT with His pacing (His-CRT) or left bundle branch pacing (LBB-CRT) in lieu of biventricular CRT. METHODS AND RESULTS: The PubMed, Embase, Web of Science, Scopus, and the Cochrane Library were systematically searched until August 19, 2023, for original studies including patients with reduced left ventricular ejection fraction (LVEF) who received His- or LBB-CRT, that reported either CSP-CRT success, LVEF, QRS duration (QRSd), or New York Heart Association (NYHA) classification. Effect measures were compared with frequentist network meta-analysis. Thirty-seven publications, including 20 comparative studies, were included. Success rates were 73.5% (95% CI: 61.2-83.0) for His-CRT and 91.5% (95% CI: 88.0-94.1) for LBB-CRT. Compared to BiV-CRT, greater improvements were observed for LVEF (mean difference [MD] for His-CRT +3.4%; 95% CI [1.0; 5.7], and LBB-CRT: +4.4%; [2.5; 6.2]), LV end-systolic volume (His-CRT:17.2mL [29.7; 4.8]; LBB-CRT:15.3mL [28.3; 2.2]), QRSd (His-CRT: -17.1ms [-25.0; -9.2]; LBB-CRT: -17.4ms [-23.2; -11.6]), and NYHA (Standardized MD [SMD]: His-CRT:0.4 [0.8; 0.1]; LBB-CRT:0.4 [-0.7; -0.2]). Pacing thresholds at baseline and follow-up were significantly lower with LBB-CRT versus both His-CRT and BiV-CRT. CSP-CRT was associated with reduced mortality (R = 0.75 [0.61-0.91]) and hospitalizations risk (RR = 0.63 [0.42-0.96]). CONCLUSION: This study found that CSP-CRT is associated with greater improvements in QRSd, echocardiographic, and clinical response. LBB-CRT was associated with lower pacing thresholds. Future randomized trials are needed to determine CSP-CRT efficacy.

Predictors of mortality and clinical outcomes following implantable cardioverter-defibrillator therapy in elderly patients: A retrospective single-center cohort study.

Background and aims: Implantable cardioverter-defibrillators (ICDs) are frequently used to prevent sudden cardiac death in patients with high-risk arrhythmias. However, the use of ICD therapy in elderly patients beyond the predicted age of life expectancy is still controversial. We aimed to evaluate the predictors of mortality and clinical outcomes following ICD implantation in elderly patients. Methods: We conducted a retrospective analysis of 145 elderly patients aged 72 years and older who received ICD implantation between January 2010 and August 2015. We collected and analyzed baseline data, including clinical, demographic, and medical history, the reason for ICD therapy, procedural data, and echocardiography results. Follow-up data included the development of complications and mortality. The predictors of mortality were identified using the univariate and multivariable Cox regression models. Results: During the median follow-up duration of 30.5 [18.0-48.0] months, 141 cases completed follow-up (mean age = 76.0 ± 3.7 years). Forty-four patients experienced at least one episode of ICD therapy. Inappropriate shock, recurrent shock, and device-related infection were the most frequent complications observed in our study. Of the 145 patients, 42 died during the follow-up period, with an average survival time of 22.4 months after ICD implantation. Among these patients, 11 received ICD for primary prevention, and 31 received it for secondary prevention. Cardiovascular problems were the leading cause of death. We found that a low baseline ejection fraction (EF) was an independent predictor of mortality (hazard ratio = 0.93, 95% confidence interval: 0.90-0.98; p = 0.008). Conclusion: Our study suggests that ICD therapy is a valuable treatment option for elderly patients beyond their predicted age of life expectancy. The study highlights the importance of baseline EF as a significant predictor of mortality in these patients.

Clinical Associations of Injuries Caused by Vasovagal Syncope: A Cohort Study From a Tertiary Syncope Unit.

Background Recent research has revealed that vasovagal syncope (VVS) leads to a high incidence of injuries; however, clinical associations of injury are not well-established. We present data from an ongoing VVS cohort and aimed to determine characteristics associated with VVS-related injury. Methods and Results Between 2017 and 2020, consecutive patients ≥18 years of age presenting to a tertiary syncope unit and diagnosed with VVS were included. Clinical characteristics relevant to syncope were obtained for the index episode. The outcome was incidence of injury during VVS, documented by clinical evaluation at the syncope clinic. Among 1115 patients (mean age, 45.9 years; 48% women), 260 injuries (23%) occurred. History of VVS-related injuries (adjusted relative risk [aRR], 1.80 [95% CI, 1.42-2.29]), standing position (aRR, 1.34 [95% CI, 1.06-1.68]), and female sex (aRR, 1.30 [95% CI, 1.06-1.60]) were associated with injury, whereas recurrent VVS (aRR, 0.63 [95% CI, 0.49-0.81]) and syncope in the noon/afternoon (aRR, 0.70 [95% CI, 0.56-0.87]) and evening/night (aRR, 0.43 [95% CI, 0.33-0.57]) compared with morning hours were associated with lower risk. There was a trend for higher rates of injury with overweight/obesity (aRR, 1.23 [95% CI, 0.99-1.54]) and syncope occurring at home (aRR, 1.22 [95% CI, 0.98-1.51]). In a per-syncope analysis considering up to 3 previous episodes (n=2518, 36% traumatic), syncope at home (aRR, 1.33 [95% CI, 1.17-1.51]) and absence of prodromes (aRR, 1.34 [95% CI, 1.09-1.61]) were associated with injury. Conclusions Patient characteristics, VVS presentations, the circumstances, and surroundings can determine the risk of injury. These associations of VVS-related injury identify at-risk individuals and high-risk situations. Future prospective studies are needed to investigate potential strategies for prevention of post-VVS injury in recurrent cases.

Implementation of supervised physical training to reduce vasovagal syncope recurrence: A randomized controlled trial.

INTRODUCTION: Physical techniques used for the prevention of vasovagal syncope have limited evidence for efficacy. We aimed to evaluate multimodal supervised physical training as a treatment approach. METHODS: In this 1:1 randomized trial, patients with ≥2 episodes of clinically diagnosed vasovagal syncope were included. On top of standard care, the intervention arm performed supervised tilt training and aerobic exercise in six sessions at a cardiac rehabilitation center (three sessions during the first month, and then at 3-month intervals), plus home tilt training. The control arm received standard care with a similar protocol of home tilt training. The primary outcome was time to first syncopal recurrence during 1 year of follow-up. RESULTS: Fifty participants were randomized (mean age: 34.5 ± 14.8 years; 64% female). The rate of syncopal recurrence was 28% and 64% within the intervention and control arms, respectively, with significantly higher syncope-free survival at 1 year in the intervention arm (Log-rank p = .003). The frequency of recurrent syncopal events was significantly lower with physical training (p = .017). Participants in the intervention arm reported significantly higher adherence to the home tilt training program (80% vs. 52%; p = .037). CONCLUSION: Among patients with recurrent vasovagal syncope, a supervised program of tilt training and aerobic exercise reduced syncopal recurrence. Future trials are warranted to further investigate multimodal supervised physical techniques as a therapeutic approach in treating vasovagal syncope.

Compression stockings for treating vasovagal syncope (COMFORTS-II) trial: Rationale and design of a triple-blind, multi-center, randomized controlled trial.

BACKGROUND: Reduced venous return is an important trigger of vasovagal syncope (VVS). Elastic compression stockings (ECS) can modify venous return and be of therapeutic interest; however, evidence for ECS efficacy in VVS is scarce. This randomized controlled trial was designed to address the issue. METHODS: COMFORTS-II is a multicenter, triple-blind, parallel design, randomized controlled trial aimed to assess the efficacy of ECS in preventing VVS recurrences. Using central online randomization, 268 participants will be allocated to 2 arms (1:1 ratio), wearing intervention ECS (25-30 mm Hg pressure) or sham ECS (≤10 mm Hg pressure). All participants will receive standard VVS treatment in the form of education, and lifestyle modification recommendations (drinking 2-3 l/d of fluids and consuming 10 g/d-roughly half a tablespoon-of table salt). Adherence to ECS treatment will be evaluated through diary sheets, and compared between study arms. Follow-up continues for 1 year, and is conducted via a 24/7 phone line available to patients and trimonthly visits. The co-primary outcomes are proportion of participants with any syncopal recurrence and time to first syncopal episode. Secondary outcomes include frequency of VVS spells, time intervals between recurrences, and incidence of any patient-reported adverse effects. CONCLUSION: To the best of our knowledge, COMFORTS-II is the first clinical trial to assess ECS efficacy among patients with VVS, addressing an important gap in evidence for VVS treatments.

Prevalence and trends of coronary artery disease risk factors and their effect on age of diagnosis in patients with established coronary artery disease: Tehran Heart Center (2005-2015).

BACKGROUND: Coronary artery disease (CAD) is a universal public health challenge, more prominently so in the low- and middle-income countries. In this study, we aimed to determine prevalence and trends of CAD risk factors in patients with documented CAD and to determine their effects on the age of CAD diagnosis. MATERIALS AND METHODS: We conducted a registry-based, serial cross-sectional study using the coronary angiography data bank of the Tehran Heart Center. Adult patients who had obstructive (> 50% stenosis) CAD were included in the study. The prevalence and 11-year trends of conventional CAD risk factors were analyzed by sex and age, and their adjusted effects on the age of CAD diagnosis were calculated. RESULTS: From January 2005 to December 2015, data for 90,094 patients were included in this analysis. A total of 61,684 (68.5%) were men and 28,410 (31.5%) were women. Men were younger at diagnosis than women, with a mean age of 60.1 in men and 63.2 in women (p < 0.001), and had fewer risk factors at the time of diagnosis. Mean age at diagnosis had an overall increasing trend during the study period. Increasing trend was seen in body-mass index, hypertension prevalence, diabetes mellitus. All lipid profile components (total cholesterol, low-density lipoprotein cholesterol, triglycerides, and high-density lipoprotein cholesterol) decreased over time. Of particular interest, opium consumption was associated with 2.2 year earlier age of CAD diagnosis. CONCLUSION: The major results of this study (lower age of CAD diagnosis in men, lower age of diagnosis associated with most risk factors, and lower prevalence of serum lipids over time) were expected. A prominent finding of this study is confirming opium use was associated with a much younger age of CAD onset, even after adjusting for all other risk factors. In addition to recommendations for control of the traditional risk factors, spreading information about the potential adverse effect of opium use, which has only recently been associated with higher risk of CAD, may be necessary.

Transforming the vaccine supply chain in Australia: Opportunities and challenges.

BACKGROUND: Analyzing potential benefits of thermostable vaccines delivered through Micro Array Patch (MAP) has received great attention in low and middle-income countries. The experience may or may not be the same in developed countries where the infrastructure is more developed. It is anticipated that transforming the vaccine supply chain from syringe-and-needle to thermostable MAP-delivered vaccines will result in reduced supply chain costs - including manufacturing/supply, logistics/distribution, and administration costs - as well as reduced wastes and improved safety. This paper provides an end-to-end supply chain analysis comparing the key aspects (cost, safety and environmental aspects) of the conventional syringe-and-needle vaccine supply chain with those of the MAP vaccine supply chain for influenza vaccine delivery in Australia. Directions for future research in this area will be provided. OBJECTIVE: To determine the potential supply chain impacts of replacing syringe-and-needle flu vaccine with MAP-enabled thermostable flu vaccine in Australia. METHODS: We analyze the current flu vaccine supply chain in Australia to identify practical limitations and opportunities for improvement. Data/information is collected through interviewing the key stakeholders across vaccine supply chain including vaccine manufacturers, logistics providers, clinics, hospitals, and pharmacies. FINDINGS: A detailed practice-informed analysis is completed on the key operations of the flu vaccine supply chain. Barriers and limitations of the conventional flu vaccine are discussed, along with potential improvements that can be achieved through the implementation of MAP-enabled flu vaccine delivery. We discuss how technology-driven innovations can help advance vaccine supply chains, improve vaccine visibility, reduce wastes, and enable informed decision-making. CONCLUSION: We find that the benefits of moving from syringe-and-needle vaccines to thermostable MAP-delivered vaccines are beyond transportation and storage cost saving. Potential benefits through cost saving, waste reduction, and service level improvement are discussed along with various safety and wellbeing consequences followed by directions for future research in this area.

Micro array patch (MAP) for the delivery of thermostable vaccines in Australia: A cost/benefit analysis.

BACKGROUND: It is anticipated that transforming the vaccine supply chain from syringe-and-needle to thermostable vaccines enabled by Micro Array Patch (MAP) will result in reduced supply chain costs as well as reduced wastes (environmental impact) and improved safety. This paper provides a thorough cost comparison of the conventional syringe-and-needle vaccine supply chain versus the MAP vaccine supply chain for influenza vaccine delivery in Australia. OBJECTIVE: To determine the potential cost implications and general benefits of replacing syringe-and-needle flu vaccine with MAP-enabled thermostable flu vaccine in Australia. METHODS: We first provide a snapshot of the existing flu vaccine supply chain in Australia including its limitations and opportunities for improvement. Data/information is collected through interviewing the key stakeholders across vaccine supply chain including vaccine manufacturers, logistics providers, clinics, hospitals, and pharmacies. A cost/benefit analysis of the anticipated supply chain of the MAP-enabled vaccine will reveal the opportunities and challenges of supply chain transformation for flu vaccine delivery in Australia. FINDINGS: Our high-level practice-informed cost/benefit analysis identifies cold chain removal as an important source of cost saving, but administrative cost savings appear to be even more significant (e.g., time saving for nurses and those involved in cold chain management). Our analysis also identifies the key benefits and limitations of vaccine supply chain transformation in Australia. CONCLUSION: We conclude that the benefits of moving from syringe-and-needle vaccines to thermostable MAP-delivered vaccines are beyond transportation and storage cost saving. Potential benefits through cost saving, waste reduction, and service level improvement are discussed along with various safety and wellbeing consequences as well as directions for future research in this area.

The effect of the mobile "blood pressure management application" on hypertension self-management enhancement: a randomized controlled trial.

BACKGROUND: Self-management of hypertension is of great significance given its increasing incidence and its associated disabilities. In view of the increased use of mobile health in medicine, the present study evaluated the effect of a self-management application on patient adherence to hypertension treatment. METHODS: This clinical trial was performed on 120 hypertensive patients who were provided with a mobile intervention for 8 weeks and followed up until the 24th week. Data on the primary outcome (adherence to treatment) and secondary outcomes (adherence to the DASH diet, regular monitoring of blood pressure, and physical activity) were collected using a questionnaire and a mobile application, respectively. The inter-group change difference over time was analyzed using repeated measures ANOVA (general linear model). RESULTS: The treatment adherence score increased by an average of 5.9 (95% CI 5.0-6.7) in the intervention group compared to the control group. The scores of "adherence to the low-fat and low-salt diet plans" were 1.7 (95% CI 1.3-2.1) and 1.5 (95% CI 1.2-1.9), respectively. Moreover, moderate physical activity increased to 100.0 min (95% CI 61.7-138.3) per week in the intervention group. CONCLUSION: The treatment and control of blood pressure require a multifaceted approach given its complexity and multifactorial nature. Considering the widespread use of smartphones, mHealth interventions can be effective in self-management and better patient adherence to treatments. Our results showed that this application can be used as a successful tool for hypertension self-management in patients attending public hospitals in developing countries. TRIAL REGISTRATION: Iran Randomized Clinical Trial Center IRCT2015111712211N2 . Registered on 1 January 2016.

Atomoxetine as an adjunct to nonpharmacological treatments for preventing vasovagal attacks in patients with recurrent vasovagal syncope: A pilot randomized-controlled trial.

BACKGROUND: Despite the reduced quality of life in patients with recurrent vasovagal syncope (VVS), pharmacologic treatment options remain limited. Studies indicate that norepinephrine reuptake inhibition reduces tilt-induced syncope/pre-syncope. This study aimed to evaluate the effects of atomoxetine on syncopal/pre-syncopal episodes in patients with recurrent VVS. METHODS: In a placebo-controlled trial, we randomized patients with newly diagnosed VVS who experienced ≥3 syncopal episodes in the past three months to receive either atomoxetine (20 mg daily for two weeks followed by 40 mg daily for two weeks) or placebo. The primary endpoint was the combined number of syncopal and pre-syncopal episodes. RESULTS: Among 843 patients initially screened, 46 were randomized (N = 23 in each group) and reevaluated at one and three months. Compared to placebo, atomoxetine significantly reduced the primary endpoint after three months (P < 0.001). In the atomoxetine arm, the median time to first pre-syncopal episode was 55 days (95% confidence interval (CI): 41.21-68.79), while this was 27 days (95% CI: 14.48-39.52) for the placebo group (P < 0.001). In a subgroup analysis of patients with systolic blood pressure < 110 mmHg, atomoxetine reduced the primary endpoint, and the number of syncopal and pre-syncopal episodes after one and three months. In this subgroup, the median time to first pre-syncopal attack was 56 days in the atomoxetine group as opposed to 9 days in the placebo group. CONCLUSIONS: In this pilot study, the promising effects of atomoxetine in reducing syncopal/pre-syncopal episodes in recurrent VVS, especially with low blood pressure phenotype, warrant the conduction of future randomized trials.

Comparison of Outcomes with Midodrine and Fludrocortisone for Objective Recurrence in Treating Syncope (COMFORTS trial): Rationale and design for a multi-center randomized controlled trial.

BACKGROUND: The cornerstone of the treatment of vasovagal syncope (VVS) is lifestyle modifications; however, some patients incur life-disturbing attacks despite compliance with these treatments which underscores the importance of pharmacological interventions. METHODS: In this open-label multi-center randomized controlled trial, we are going to randomize 1375 patients with VVS who had ≥2 syncopal episodes in the last year into three parallel arms with a 2:2:1 ratio to receive midodrine, fludrocortisone, or no medication. All patients will be recommended to drink 2 to 3 liters of fluids per day, consume 10 grams of NaCl per day, and practice counter-pressure maneuvers. In medication arms, patients will start on 5 mg of midodrine TDS or 0.05 mg of fludrocortisone BD. After one week the dosage will be up-titrated to midodrine 30 mg/day and fludrocortisone 0.2 mg/day. Patient tolerance will be the principal guide to dosage adjustments. We will follow-up the patients on 3, 6, 9, and 12 months after randomization. The primary outcome is the time to first syncopal episode. Secondary outcomes include the recurrence rate of VVS, time interval between first and second episodes, changes in quality of life (QoL), and major and minor adverse drug reactions. QoL will be examined by the 36-Item Short Form Survey questionnaire at enrollment and 12 months after randomization. CONCLUSION: The COMFORTS trial is the first study that aims to make a head-to-head comparison between midodrine and fludrocortisone, against a background of lifestyle modifications for preventing recurrences of VVS and improving QoL in patients with VVS.

Effect of COVID-19 medications on corrected QT interval and induction of torsade de pointes: Results of a multicenter national survey.

BACKGROUND: There are some data showing that repurposed drugs used for the Coronavirus disease-19 (COVID-19) have potential to increase the risk of QTc prolongation and torsade de pointes (TdP), and these arrhythmic side effects have not been adequately addressed in COVID-19 patients treated with these repurposed medications. METHODS: This is the prospective study of 2403 patients hospitalised at 13 hospitals within the COVID-19 epicentres of the Iran. These patients were treated with chloroquine, hydroxychloroquine, lopinavir/ritonavir, atazanavir/ritonavir, oseltamivir, favipiravir and remdesivir alone or in combination with azithromycin. The primary outcome of the study was incidence of critical QTc prolongation, and secondary outcomes were incidences of TdP and death. RESULTS: Of the 2403 patients, 2365 met inclusion criteria. The primary outcome of QTc ≥ 500 ms and ∆QTc ≥ 60 ms was observed in 11.2% and 17.6% of the patients, respectively. The secondary outcomes of TdP and death were reported in 0.38% and 9.8% of the patients, respectively. The risk of critical QT prolongation increased in the presence of female gender, history of heart failure, treatment with hydroxychloroquine, azithromycin combination therapy, simultaneous furosemide or beta-blocker therapy and acute renal or hepatic dysfunction. However, the risk of TdP was predicted by treatment with lopinavir-ritonavir, simultaneous amiodarone or furosemide administration and hypokalaemia during treatment. CONCLUSION: This cohort showed significant QTc prolongation with all COVID-19 medications studied, however, life-threatening arrhythmia of TdP occurred rarely. Among the repurposed drugs studied, hydroxychloroquine or lopinavir-ritonavir alone or in combination with azithromycin clearly demonstrated to increase the risk of critical QT prolongation and/or TdP.