Utility of Substrate Mapping Using Extrasystole to Localise Comprehensive Ventricular Tachycardia Circuits: Results From Intra-operative Mapping Studies.

BACKGROUND: Substrate mapping-based identification of all ventricular tachycardia (VT) circuits (diastolic activation), including partial and complete diastolic circuits in clinical and nonclinical VT, could be beneficial in guiding VT ablation to prevent VT recurrence. The utility of extrasystole induced late potentials has not been compared with late potentials in sinus rhythm (SR) and right ventricular pacing (RVp). METHODS: Intraoperative simultaneous panoramic endocardial mapping of 21 VTs in 16 ischemic heart disease patients was performed with the use of a 112-bipole endocardial balloon. The decrement of near-field electrogram later than surface QRS during extrasystole (eLP) was studied. RESULTS: Patients had a mean age of 52 ± 9 years and were predominantly (75%) male. The mean sensitivity of eLP (0.75 [95% confidence interval [CI] 0.72-0.78]) to detect VT circuits was better than SR (0.33 [0.30-0.36]; P < 0.001) and RVp (0.36 [0.33-0.39]; P < 0.001) without significant differences in specificity, eLP (0.77 [0.74-0.81], SR (0.82 [0.80-0.84]; P = 0.23), and RVp (0.81 [0.78-0.83]; P = 0.11). Both negative (NPV) and positivie (PPV) predictive values were significantly better for eLP mapping. The mean NPV was 0.77 (95% CI 0.74-0.81), 0.57 (0.55-0.59), and 0.58 (0.55-0.61) for eLP, SR, and RVp, respectively (P < 0.0001). PPV was 0.75 (95% CI 0.72-0.78), 0.63 (0.59-0.67), and 0.63 (0.59-0.67) for eLP, SR, and RVp, respectively (P < 0.001). Overall diagnostic performance (area under the receiver operating characteristic curve) was significantly better for eLP (0.85 [95% CI 0.80-0.90] compared with SR (0.63 [0.56-0.72]; P < 0.001) or RVp (0.61 [0.52-0.74]; P < 0.001). CONCLUSIONS: Evoked late potential mapping is a better tool to detect comprehensive diastolic circuits activated during VT, compared with eLP mapping in sinus rhythm or RV pacing.

Orientation of conduction velocity vectors on cardiac mapping surfaces.

AIMS: Electroanatomical maps using automated conduction velocity (CV) algorithms are now being calculated using two-dimensional (2D) mapping tools. We studied the accuracy of mapping surface 2D CV, compared to the three-dimensional (3D) vectors, and the influence of mapping resolution in non-scarred animal and human heart models. METHODS AND RESULTS: Two models were used: a healthy porcine Langendorff model with transmural needle electrodes and a computer stimulation model of the ventricles built from an MRI-segmented, excised human heart. Local activation times (LATs) within the 3D volume of the mesh were used to calculate true 3D CVs (direction and velocity) for different pixel resolutions ranging between 500 µm and 4 mm (3D CVs). CV was also calculated for endocardial surface-only LATs (2D CV). In the experimental model, surface (2D) CV was faster on the epicardium (0.509 m/s) compared to the endocardium (0.262 m/s). In stimulation models, 2D CV significantly exceeded 3D CVs across all mapping resolutions and increased as resolution decreased. Three-dimensional and 2D left ventricle CV at 500 µm resolution increased from 429.2 ± 189.3 to 527.7 ± 253.8 mm/s (P < 0.01), respectively, with modest correlation (R = 0.64). Decreasing the resolution to 4 mm significantly increased 2D CV and weakened the correlation (R = 0.46). The majority of CV vectors were not parallel (<30°) to the mapping surface providing a potential mechanistic explanation for erroneous LAT-based CV over-estimation. CONCLUSION: Ventricular CV is overestimated when using 2D LAT-based CV calculation of the mapping surface and significantly compounded by mapping resolution. Three-dimensional electric field-based approaches are needed in mapping true CV on mapping surfaces.

On the Electrophysiology and Mapping of Intramural Arrhythmic Focus.

BACKGROUND: Conventional mapping of focal ventricular arrhythmias relies on unipolar electrogram characteristics and early local activation times. Deep intramural foci are common and associated with high recurrence rates following catheter-based radiofrequency ablation. We assessed the accuracy of unipolar morphological patterns and mapping surface indices to predict the site and depth of ventricular arrhythmogenic focal sources. METHODS: An experimental beating-heart model used Langendorff-perfused, healthy swine hearts. A custom 56-pole electrode array catheter was positioned on the left ventricle. A plunge needle was placed perpendicular in the center of the grid to simulate arrhythmic foci at variable depths. Unipolar electrograms and local activation times were generated. Simulation models from 2 human hearts were also included with grids positioned simultaneously on the endocardium-epicardium from multiple left ventricular, septal, and outflow tract sites. RESULTS: A unipolar Q or QS complex lacks specificity for superficial arrhythmic foci, as this morphology pattern occupies a large surface area and is the predominant pattern as intramural depth increases without developing a R component. There is progressive displacement from the arrhythmic focus to the surface exit as intramural focus depth increases. A shorter total activation time over the overlying electrode array, larger surface area within initial 20 ms activation, and a dual surface breakout pattern all indicate a deep focus. CONCLUSIONS: Displacement from the focal intramural origin to the exit site on the mapping surface could lead to erroneous lesion delivery strategies. Traditional unipolar electrogram features lack specificity to predict the intramural arrhythmic source; however, novel endocardial-epicardial mapping surface indices can be used to determine the depth of arrhythmic foci.

Multi-Axes Lead With Tetrahedral Electrode Tip for Cardiac-Implantable Devices: Creative Concept for Pacing and Sensing Technology.

BACKGROUND: We developed a multi-axes lead (MaxLead) incorporating 4 electrodes arranged at the lead-tip, organized in an equidistant tetrahedron. Here, we studied MaxLead performance in sensing, pacing, and activation wavefront-direction analysis. METHODS: Sixteen explanted animal hearts (from 7 pigs, 7 sheep, and 2 rabbits) were used. Pacing threshold was tested from all axes of MaxLead from right-ventricular (RV) apex before and after simulated dislodgement. In addition, conduction-system pacing was performed in sheep heart preparations from all axes of MaxLead. Sensing via MaxLead positioned at RV apex was tested during sinus rhythm (SR), pacing from RV and left-ventricular (LV) free-wall, and ventricular fibrillation (VF). MaxLead-enabled voltage (MaxV), defined as the largest span of the sensed electric field loop, was compared with traditional lead-tip voltage detection. RESULTS: Pacing: MaxLead minimized change in pacing threshold owing to lead dislodgement (average voltage change 0.2 mV; 95% confidence interval [CI], -0.5 to 0.9), using multiple bipoles available for pacing. In animals with high conduction system-pacing thresholds (> 2 mV) in 1 or more bipoles (3 of 7), acceptable thresholds (< 1 mV) were demonstrated in an average of 2.5 remaining bipoles. Sensing: MaxV of SR and VF was consistently higher than the highest bipolar voltage (voltage difference averaged -0.18 mV, 95% CI, -0.28 to -0.07), P = 0.001). Electric field-loop geometry consistently differentiated ventricular activation in SR from that during pacing from RV and LV free walls. CONCLUSIONS: The multi-axes MaxLead electrode showed advantages in pacing, sensing, and mapping and has the potential to allow for improvements in lead-electrode technology for cardiac-implanted electronic devices.

High density intramural mapping of post-infarct premature ventricular contractions and ventricular tachycardia.

BACKGROUND: Spontaneous ventricular premature contractions (PVCs) and ventricular tachycardia (VT) in the acute post infarct milieu is assumed to be due to automaticity. However, the mechanism has not been studied with intramural mapping. OBJECTIVE: To study the mechanism of spontaneous PVCs with high density intramural mapping in a canine model, and to test the hypothesis that post-infarct PVCs and VT are due to re-entry rather than automaticity. METHODS: In 15 anesthetized dogs, using 768 intramural unipolar electrograms, simultaneous recordings were made. After 20 min of stabilization, recordings were made during the first 10 min of ischemia, and activation maps of individual beats were constructed. Acute ischemia was produced by clamping the left anterior descending coronary artery proximal to the first diagonal branch. RESULTS: In all experiments ST-T alternans was present. Spontaneous ventricular beats occurred in five of 15 dogs where the earliest ectopic activity was manifested in the endocardium, well within the ischemic zone. From there, activity spread rapidly along the subendocardium, with endo-to epicardial spread along the non-ischemic myocardium. Epicardial breakthrough always occurred at the border of the ischemic myocardium. In three dogs, delayed potentials were observed, which were earliest at the ischemic epicardium and extended transmurally with increasing delay towards the endocardium, where they culminated in a premature beat. A similar sequence was observed in VT that followed. CONCLUSION: Graded responses that occur with each sinus beat intramurally, when able to propagate from epicardium to endocardium are the mechanism of PVCs and VT in post-infarct myocardium.

Safety, efficacy, and monitoring of bipolar radiofrequency ablation in beating myopathic human and healthy swine hearts.

BACKGROUND: The safety and efficacy parameters for bipolar radiofrequency (RF) ablation are not well defined. OBJECTIVE: The purpose of this study was to investigate the safe range of power, utility of transmyocardial bipolar electrogram (EGM) amplitude, and circuit impedance in ablation monitoring. METHODS: Sixteen beating ex vivo human and swine hearts were studied in a Langendorff setup. Ninety-two bipolar ablations using two 4-mm irrigated catheters were performed at settings of 20-50 W, 60 seconds, and 30 mL/min irrigation in the left ventricle. RESULTS: For low-power ablations (20 and 30 W), transmurality was observed in 29 of 38 (76%) and 10 of 28 (36%) ablations for tissue thickness ≤17 mm and >17 mm, respectively. For high-power ablations (40 and 50 W), transmurality was observed in 5 of 7 (71%) and 7 of 19 (37%) ablations for tissue thickness ≤17 mm and >17 mm, respectively. Steam pop occurrence for low- and high-power ablations was 11 of 66 (16%) and 16 of 26 (62%), respectively (P = .0001), respectively. Lesion depth (limited by transmurality) was 12.0 ± 5.7 mm and 12.3 ± 5.8 mm, respectively (P = 1). Transmyocardial EGM amplitude decrement >60% strongly predicted transmurality (area under the curve [AUC] 0.8), and circuit impedance decrement >26% predicted steam pops (AUC 0.75). Half-normal saline did not affect transmurality or incidence of steam pops compared to normal saline irrigation. CONCLUSION: Bipolar RF ablation at power of 20-30 W provided an ideal balance of safety and efficacy, whereas power ≥40 W should be used with caution due to the high incidence of steam pops. Lesion transmurality monitoring and steam pop avoidance were best achieved using transmyocardial bipolar EGM voltage and circuit impedance, respectively.

The Role of Ablation in Prevention of Recurrent Implantable Cardioverter Defibrillator Shocks in Patients With Tetralogy of Fallot.

BACKGROUND: Implantable cardioverter defibrillators (ICDs) are effective in preventing arrhythmic sudden cardiac death in patients with tetralogy of Fallot (TOF). Although ICD therapies for malignant ventricular arrhythmias can be life-saving, shocks could have deleterious consequences. Substrate-based ablation therapy has become the standard of care to prevent recurrent ICD shocks in patients with ischemic cardiomyopathy. However, the efficacy and safety of this invasive therapy in the prevention of recurrent ICD shocks in patients with TOF has not been well evaluated. METHODS: Records of a total of 47 consecutive TOF patients (mean age: 43.1 ± 13.2 years, male sex: n = 34 [72.3%]) who underwent ICD implantation for secondary prevention between 2000 and 2018 were reviewed. RESULTS: Twenty (42.6%) patients underwent invasive therapy (radiofrequency catheter ablation, n = 8; surgical ablation with pulmonary valve replacement, n = 12) before ICD implantation. Twenty-seven patients (57.4%) were managed noninvasively. During follow-up (median 80.5 [interquartile range, 28.5-131.0] months), 2 (10.0%) patients in the invasive group and 10 (37.0%) patients in the noninvasive group received appropriate ICD shocks (P = 0.036). Logistic regression analysis showed that invasive therapy was associated with a decreased risk of ICD shocks by 81.1% (odds ratio, 0.189; 95% confidence interval, 0.036-0.990; P = 0.049). Furthermore, invasive therapy was associated with decreased risk of the composite outcomes of ICD shock, death, cardiac transplantation, and hospital admission (odds ratio, 0.090; 95% confidence interval, 0.025-0.365; P = 0.013) compared with noninvasive therapy. CONCLUSIONS: Invasive substrate modification therapy was associated with a lower likelihood of ICD shocks and improvement of long-term outcomes in TOF patients.

CONTEXTE: Les défibrillateurs cardioverteurs implantables (DCI) sont efficaces pour prévenir la mort cardiaque subite provoquée par une arythmie chez les patients présentant une tétralogie de Fallot (TF). Bien que le traitement des arythmies ventriculaires malignes par DCI puisse sauver des vies, les chocs administrés peuvent avoir des conséquences délétères. L'ablation du substrat est devenue le traitement de référence pour prévenir l'administration à répétition de chocs par DCI chez les patients atteints d'une cardiomyopathie ischémique. L'efficacité et l'innocuité de ce traitement invasif pour prévenir l'administration de chocs répétés chez les patients présentant une TF n'ont toutefois pas été bien évaluées. MÉTHODOLOGIE: Nous avons examiné les cas consécutifs de 47 patients présentant une TF (âge moyen : 43,1 ± 13,2 ans; hommes : n = 34 [72,3 %]) ayant reçu un DCI en prévention secondaire entre 2000 et 2018. RÉSULTATS: Au total, 20 (42,6 %) patients ont subi un traitement invasif (ablation par cathéter par radiofréquence, n = 8; ablation chirurgicale et remplacement de la valve pulmonaire, n = 12) avant l'implantation d'un DCI. Vingt-sept patients (57,4 %) ont été pris en charge de façon non invasive. Au cours de la période de suivi (durée médiane de 80,5 [intervalle interquartile : 28,5 à 131,0] mois), 2 (10,0 %) patients du groupe ayant subi une intervention invasive et 10 (37,0 %) patients du groupe ayant subi une intervention non invasive ont reçu un choc approprié par DCI (p = 0,036). Les résultats de l'analyse par régression logistique montrent que le traitement invasif est associé à une réduction du risque de choc par DCI de 81,1 % (rapport des cotes : 0,189; intervalle de confiance à 95 % : de 0,036 à 0,990; p = 0,049). En outre, le traitement invasif est associé à une réduction du risque de survenue d'un des événements du paramètre d'évaluation composé, soit un choc administré par DCI, le décès, une transplantation cardiaque ou une hospitalisation (rapport des cotes : 0,090; intervalle de confiance à 95 % : de 0,025 à 0,365; p = 0,013) par rapport au traitement non invasif. CONCLUSIONS: La modification invasive du substrat a été associée à une probabilité plus faible de choc administré par DCI et à une amélioration des résultats à long terme chez les patients présentant une TF.

Implementation of Cardiac Stereotactic Radiotherapy: From Literature to the Linac.

Stereotactic radiotherapy (SBRT) has been applied to treat cardiac arrhythmias, but our institution had not yet implemented this technique. Here, we explain how we used implementation science and knowledge translation to provide cardiac SBRT to a critically ill patient with malignancy-associated refractory ventricular tachycardia. We reviewed the critical factors that enabled the implementation of this urgent treatment, such as the context of the implementation, the characteristics of the intervention, and the stakeholders. These principles can be used by other radiation programs to implement novel treatments in urgent settings, where the gold standard process of planning and developing policies and protocols is not possible.

Stimulation and propagation of activation in conduction tissue: Implications for left bundle branch area pacing.

BACKGROUND: Characterizing wavefront generation and impulse conduction in left bundle (LB) has implications for left bundle branch area pacing (LBBAP). OBJECTIVES: The purpose of this study was to describe the pacing characteristics of LB and to study the role of pacing pulse width (PW) in overcoming left bundle branch block. METHODS: Twenty fresh ovine heart slabs containing well-developed and easily identifiable tissues of the conduction system were used for the study. LB stimulation, activation, and propagation were studied under baseline conditions, simulated conduction slowing, conduction block, and fascicular block. RESULTS: The maximum radius of the LB early activation increased up to 13.4 ± 2.4 mm from the pacing stimulus, and the time from stimulus to evoked potential shortened when pacing PW was increased from 0.13 to 2 ms at baseline. Conduction slowing and block induced by cooling could be resolved by increasing pacing PW from 0.25 to 1.5 ms over a distance of 10 ± 1.5 mm from the pacing stimulus. The LB strength-duration (SD) curve was shifted to the left of the myocardial SD curve. CONCLUSION: Increasing PW resolved conduction slowing and block and bypassed the experimental model of fascicular block in LB. Precise positioning of the LB lead in left ventricular subendocardium is not mandatory in LBBAP, as the SD curve of LB was shifted to the left of the myocardium SD curve and could be captured from a distance by optimizing PW.

Safety and Long-term Outcomes of Defibrillator Therapy in Patients With Right-Sided Implantable Cardiac Devices in Adults With Congenital Heart Disease.

BACKGROUND: Implantable cardioverter-defibrillators (ICDs) have been proven to prevent sudden cardiac death in adult congenital heart disease (ACHD) patients. Although the left side is chosen by default, implantation from the right side is often required. However, little is known about the efficacy and safety of right-sided ICDs in ACHD patients. METHODS: In this study we reviewed a total of 191 ACHD patients undergoing ICD/cardioverter resynchronisation therapy-defibrillator (CRT-D) implantation at our hospital between 2001 and 2019 (134 men and 57 women; age [mean ± standard deviation], 41.5 ± 14.8 years). RESULTS: Twenty-seven patients (14.1%) had right-sided devices. The most common causes of right-sided implantation were persistent left superior vena cava and vein occlusion (37.0%). Although procedure time (202.8 ± 60.5 minutes vs 143.8 ± 69.1 minutes, P = 0.008) was longer and the procedural success was lower (92.6% vs 99.4%, P = 0.008) for right-sided devices, no difference in R-wave and pacing threshold were noted. Among the 47 patients (24.6%) who underwent defibrillation threshold testing (DFT), no difference in DFT was observed (25.2 ± 5.3 J vs 23.8 ± 4.1 J, P = 0.460). During the median follow-up of 42.4 months, appropriate ICD therapy was observed in 5 (18.5%) and 30 (18.3%) patients for right- and left-sided ICDs/CRTDs, respectively (P = 0.978). No significant difference was seen in complications between them. CONCLUSIONS: Implantation of an ICD on the right side is technically challenging, but it is feasible as an alternative approach for ACHD patients with contraindications to left-sided device implantation.

Mortalité, congé et arythmie chez les patients ayant la COVID-19 et une atteinte cardiaque.

CONTEXTE: Les atteintes cardiaques sont fréquentes dans les cas graves de maladie à coronavirus 2019 (COVID-19) et sont associées à un mauvais pronostic. Notre étude portait sur les facteurs prédictifs de mortalité intrahospitalière, les caractéristiques de l'arythmie et les effets des traitements qui allongent l'intervalle QT chez les patients ayant une atteinte cardiaque. MÉTHODES: Nous avons fait une étude de cohorte rétrospective des cas graves de COVID-19 admis à l'hôpital Tongji, à Wuhan, en Chine, entre le 29 janvier et le 8 mars 2020. En examinant ceux qui avaient une atteinte cardiaque, définie ici comme un taux élevé de troponine I cardiaque (TnIc), nous avons déterminé les caractéristiques biologiques et cliniques associées à la mortalité et au besoin de ventilation invasive. RÉSULTATS: Parmi les 1284 cas graves de COVID-19, 1159 avaient au dossier un taux de TnIc mesuré à l'admission, qui pour 170 (14,7 %) participants indiquait une atteinte cardiaque. Les patients ayant une atteinte cardiaque avaient un taux de mortalité nettement plus élevé que les autres patients (71,2 % c. 6,6 %; p < 0,001). Nous avons constaté que le taux de TnIc initial (pour chaque augmentation d'un facteur 10, rapport de risque [HR] 1,32, intervalle de confiance [IC] à 95 % 1,06­1,66) et le taux de TnIc maximal atteint au cours de la maladie (pour chaque augmentation d'un facteur 10, HR 1,70, IC à 95 % 1,38­2,10) étaient associés à de minces chances de survie. Le taux de TnIc maximal était aussi associé au besoin de ventilation invasive (rapport de cotes 3,02, IC à 95 % 1,92­4,98). Sur les 170 patients ayant une atteinte cardiaque, 44 (25,9 %) présentaient une arythmie. Les 6 qui souffraient de tachycardie ou de fibrillation ventriculaires sont morts. Nous avons remarqué que les patients qui recevaient des médicaments allongeant l'intervalle QT avaient un intervalle QTc plus long que ceux qui n'en recevaient pas (différence entre les médianes 45 ms; p = 0,01), mais que ce traitement n'était pas directement lié à la mortalité (HR 1,04, IC à 95 % 0,69­1,57). INTERPRÉTATION: Chez les patients ayant la COVID-19 et une atteinte cardiaque, les taux initial et maximal de TnIc sont associés à de minces chances de survie, et le taux maximal est un facteur prédictif du besoin de ventilation invasive. Les malades de la COVID-19 doivent subir un dépistage des atteintes cardiaques et être surveillés, surtout si on leur fait suivre un traitement qui peut prolonger la repolarisation. Enregistrement de l'essai : Registre des essais cliniques chinois, n° ChiCTR2000031301.

Minimalistic strategy for coronary sinus lead implant: A single tool capable of electrophysiological mapping, pressure measurement, and angiography.

BACKGROUND: Left ventricular (LV) lead implantation for cardiac resynchronization therapy (CRT) may be confounded by contrast load during attempted cannulation and lead dislodgement during guiding catheter splitting. An LV lead implant system with a steerable single catheter that completely avoids the use of guiding catheters when needed, acquires atrioventricular electrograms, measures intracardiac pressures, permits CS angiography, and has the ability to direct a coronary angioplasty wire that will lead the final delivery of LV lead into a CS tributary, may help limit contrast use and avoid lead dislodgement at CS guide sheath removal. METHODS AND RESULTS: In this article as a proof of concept, we describe the use of this minimalist technique as a first line approach in six patients who had standard indications for CRT. The LV lead was successfully implanted in a target vein in all patients without acute complications. Contrast was not used in half the group and the LV lead was successfully implanted without guiding catheter in four patients. The implantation technique evolved through the series and in the final patient, no guiding sheath or contrast was used. Postimplant lead positions on chest X-ray and lead parameters were stable in all patients at follow-up. CONCLUSION: In proof of concept paper, we describe a technique of LV lead implantation potentially without the use of contrast and standard CS guiding catheters. Once familiar, this approach may provide a less complicated strategy.

Signature signal strategy: Electrogram-based ventricular tachycardia mapping.

Multiple decades of work have recognized complexities of substrates responsible for ventricular tachycardia (VT). There is sufficient evidence that 3 critical components of a re-entrant VT circuit, namely, region of slow conduction, zone of unidirectional block, and exit site, are located in spatial vicinity to each other in the ventricular scar. Each of these components expresses characteristic electrograms in sinus rhythm, at initiation of VT, and during VT, respectively. Despite this, abnormal electrograms are widely targeted without appreciation of these signature electrograms during contemporary VT ablation. Our aim is to stimulate physiology-based VT mapping and a targeted ablation of VT. In this article, we focus on these 3 underappreciated aspects of the physiology of ischemic scar-related VT circuits that have practical applications during a VT ablation procedure. We explore the anatomic and functional elements underlying these distinctive bipolar electrograms, specifically the contribution of tissue branching, conduction restitution, and wave curvature to the substrate, as they pertain to initiation and maintenance of VT. We propose a VT ablation approach based on these 3 electrogram features that can be a potential practical means to recognize critical elements of a VT circuit and target ablation.

Death, discharge and arrhythmias among patients with COVID-19 and cardiac injury.

BACKGROUND: Cardiac injury is common in severe coronavirus disease 2019 (COVID-19) and is associated with poor outcomes. We aimed to study predictors of in-hospital death, characteristics of arrhythmias and the effects of QT-prolonging therapy in patients with cardiac injury. METHODS: We conducted a retrospective cohort study involving patients with severe COVID-19 who were admitted to Tongji Hospital in Wuhan, China, between Jan. 29 and Mar. 8, 2020. Among patients who had cardiac injury, which we defined as an elevated level of cardiac troponin I (cTnI), we identified demographic and clinical characteristics associated with mortality and need for invasive ventilation. RESULTS: Among 1284 patients with severe COVID-19, 1159 had a cTnI level measured on admission to hospital, of whom 170 (14.7%) had results that showed cardiac injury. We found that mortality was markedly higher in patients with cardiac injury (71.2% v. 6.6%, p < 0.001). We determined that initial cTnI (per 10-fold increase, hazard ratio [HR] 1.32, 95% confidence interval [CI] 1.06-1.66) and peak cTnI level during illness (per 10-fold increase, HR 1.70, 95% CI 1.38-2.10) were associated with poor survival. Peak cTnI was also associated with the need for invasive ventilation (odds ratio 3.02, 95% CI 1.92-4.98). We found arrhythmias in 44 of the 170 patients with cardiac injury (25.9%), including 6 patients with ventricular tachycardia or fibrillation, all of whom died. We determined that patients who received QT-prolonging drugs had longer QTc intervals than those who did not receive them (difference in medians, 45 ms, p = 0.01), but such treatment was not independently associated with mortality (HR 1.04, 95% CI 0.69-1.57). INTERPRETATION: We found that in patients with COVID-19 and cardiac injury, initial and peak cTnI levels were associated with poor survival, and peak cTnI was a predictor of need for invasive ventilation. Patients with COVID-19 warrant assessment for cardiac injury and monitoring, especially if therapy that can prolong repolarization is started. TRIAL REGISTRATION: Chinese Clinical Trial Registry, No. ChiCTR2000031301.