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Association Between Left Ventricular Ejection Fraction Post-Cardiac Resynchronization Treatment and Subsequent ICD Therapy for Sustained Ventricular Tachyarrhythmias
Study Questions:
What is the association between left ventricular ejection fraction (LVEF) after cardiac resynchronization therapy (CRT) treatment and future appropriate ICD therapy for sustained ventricular tachycardia and ventricular fibrillation?
Methods:
This was a single-center retrospective study of 423 patients who received an implantable cardioverter-defibrillator (ICD) with CRT-defibrillator (CRT-D). Patients included had systolic heart failure (ischemic or nonischemic) and an LVEF of ≤35%, with New York Heart Association functional class III/IV on optimal medical therapy. A total of 270 patients with measured post-CRT-D LVEF and no ICD therapy within 1 year of device implantation were followed. The primary endpoint was time to appropriate ICD therapy defined as antitachycardia pacing and high-voltage shocks for ventricular arrhythmias. The secondary endpoint was post-CRT-D LVEF of ≥45%. Follow-up measurements to assess CRT-D LVEF were left at the discretion of the attending electrophysiologist.
Results:
The median age of patients was 72 years. The median follow-up was 2.64 years (interquartile range, 1.84-3.20 years); 71% of the patients were male, 61% had ischemic cardiomyopathy, and 81% had ICD therapy placement for primary prevention. Of the 270 patients analyzed at 1 year, 8.2% had subsequent appropriate ICD therapy over a median follow-up of 1.5 years. The estimated 2-year risk of appropriate ICD therapy was 3.0% (95% confidence interval [CI], 0-6.3%), 2.1% (95% CI, 0-5.0%), and 1.5% (95% CI, 0-3.9%) for post-CRT-D LVEF of 45%, 50%, and 55%, respectively. In patients with a primary prevention indication for CRT-D, the estimated 2-year risk is 3.3% (95% CI, 0-7.3%), 2.5% (95% CI, 0-6.1%), and 1.9% (95% CI, 0-5.1%) for post-CRT-D LVEF of 45%, 50%, and 55%, respectively.
Conclusions:
With improvement in post-CRT-D LVEF to ≥45%, the risk of appropriate ICD therapy decreases for sustained tachyarrhythmias, raising the concern for future decisions on the type of CRT device to be designated at time of generator change.
Perspective:
CRT treatment can demonstrate an unpredictable improvement in LVEF. This study demonstrates the increased need for future studies to help determine the role of ICD therapy in patients who demonstrate an improvement in LVEF with CRT treatment. The potential role of predicting patients who would benefit from CRT-pacing versus CRT-D with improvement in CRT-D LVEF could have a crucial economic impact.
Keywords: Myocardial Ischemia, Ventricular Function, Left, Ventricular Fibrillation, Heart Failure, Systolic, Tachycardia, Cardiac Resynchronization Therapy, Heart Diseases, Tachycardia, Ventricular, Cardiac Pacing, Artificial, Pacemaker, Artificial, Stroke Volume, Confidence Intervals, Defibrillators, Implantable
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