Long-Term Clinical Course of Patients After Termination of Ventricular Tachyarrhythmia by an Implanted Defibrillator

Abstract

Background-The implanted cardioverter defibrillator (ICD) improves survival in high-risk cardiac patients. This analysis from the MADIT-II trial database examines the long-term clinical course and subsequent mortality risk of patients after termination of life-threatening ventricular tachyarrhythmias by an ICD. Methods and Results-Life-table survival analysis was performed, and proportional hazards regression analysis was used to evaluate the contribution of baseline clinical factors and time-dependent defibrillator therapy to mortality during long-term follow-up. Of 720 patients with an ICD (average follow-up 21 months), 169 patients received 701 antiarrhythmic device therapies for ventricular tachyarrhythmias. Few baseline characteristics distinguished patients who received appropriate ICD therapy for their first ventricular tachyarrhythmic episode. The probability of survival for at least 1 year after first therapy for ventricular tachycardia (VT) or ventricular fibrillation (VF) was 80%. The hazard ratios for the risk of death due to any cause in those who survived appropriate therapy for termination of VT and VF were 3.4 (PϽ0.001) and 3.3 (Pϭ0.01), respectively, compared with those who survived without receiving ICD therapy, with a high frequency of heart failure and late nonsudden cardiac death after first successful ICD therapy for VF. Conclusions-Successful appropriate therapy by an ICD for VT or VF is associated with 80% survival at 1 year after arrhythmia termination. These patients are at increased risk for heart failure and nonsudden cardiac death after device termination of VT or VF and should receive special attention for the prevention and management of progressive left ventricular dysfunction during long-term follow-up.

Device Therapies Among Patients Receiving Primary Prevention Implantable Cardioverter‐Defibrillators in the Cardiovascular Research Network

“…For example, the 3‐year cumulative therapy rate was lower than reported in MADIT (Multicenter Automatic Defibrillator Implantation Trial) II, for both appropriate therapies (34% versus 24%)21 and inappropriate therapies (18% versus 12%) 22. Several factors may explain this.…”

What factors lead to the acceleration of ventricular tachycardia during antitachycardia pacing?—Results from over 1000 episodes

“…Although ICD shocks could terminate those arrhythmias immediately, they would result in both physical and psychological damages and even increase the mortality and hospitalization as proved in some previous studies 2, 3, 4…”

Clinical trials of antiarrhythmic therapies and optimizing health care resource deployment: the need for a paradigm shift

“…Similar situations exist in trials employing implantable cardioverterdefibrillators (ICDs) for sudden death prophylaxis in patients with renal dysfunction and class IV heart failure [4,8]. Other baseline variables influence outcomes only with specific interventions, for example, amiodarone use in atrial fibrillation patients with preexisting or treated thyroid disease or high energy shocks in patients with impaired left ventricular function and comorbidities [6,7].…”

“…Recently, these foundational clinical trials have been revisited in part or in great measure [6,7]. These reports have been both enlightening and concerning.…”

“…High-energy shocks may cause ventricular stunning and cardiac enzyme release which has variable tolerance in patients with left ventricular dysfunction [7]. Amiodarone promotes more serious cardiovascular hospitalizations and increases noncardiac mortality by hitherto unrecognized mechanisms [6].…”