Do ICD diagnostics predict failure of ventricular tachycardia response to antitachycardia pacing and need for shock?

Abstract

Background: Among heart failure patients with implantable cardioverter defibrillators (ICDs), monomorphic ventricular tachycardia (MMVT) failing antitachycardia pacing (ATP) and terminated by shock renders higher mortality as compared to MMVT terminated by ATP only. It is unknown if the higher mortality in ATP failure reflects decompensated heart failure. Objective: It was the purpose of the present study to determine if ICD heart failure diagnostics can predict the failure of ATP and the need to shock to terminate MMVT. Methods: This was a single-center retrospective review of 103 consecutive patients with Medtronic ICDs who had MMVT and received ICD therapy. Heart failure diagnostics preceding each MMVT event were reviewed including atrial fibrillation burden, patient activity, night heart rate, heart rate variability, Optivol ® fluid index, and MMVT heart rate. Results: A total of 452 MMVT events were analyzed, of which 23% required shock. Compared to MMVT that responded to ATP, MMVT that failed ATP and required shock had significantly faster heart rates and higher atrial fibrillation burden. Patient activity, night heart rate, heart rate variability, and OptiVol ® fluid index were similar between ATP responsive MMVT events and those that failed ATP. In a multivariate analysis adjusting for baseline characteristics, higher atrial fibrillation burden and lower patient activity were associated with ATP failure and shock termination. Conclusion: Device diagnostics associated with decompensated heart failure identified MMVT events that failed ATP and necessitated shock. K E Y W O R D S antitachycardia pacing, implantable cardioverter defibrillator diagnostics 1 INTRODUCTION In a subset of heart failure patients, implantable cardioverter defibrillators (ICD) are associated with mortality reduction through terminating Abbreviations: ATP, antitachycardia pacing; CRT-D, cardiac resynchronization therapy with defibrillator; ICD, implantable cardioverter defibrillator; MMVT, monomorphic ventricular tachycardia ventricular tachyarrhythmia. 1-3 An ICD device can terminate a ventricular tachyarrhythmia through either antitachycardia pacing (ATP) or shock. Previous studies have demonstrated that among patients who received ICDs, those patients who received shocks to terminate ventricular tachyarrhythmias had higher mortality rates compared to those patients who did not receive a shock. 4-6 However, appropriate termination of ventricular tachyarrhythmia with ATP had