SAN FRANCISCO – Inappropriate implantable cardioverter defibrillator (ICD) shocks for atrial fibrillation/flutter lead to increased risk of death during the next several years, while inappropriate shocks for sinus tachycardia, supraventricular tachycardia, artifact, noise, or device oversensing are associated with the same survival as in patients who did not receive a shock.
This was the key finding in the ALTITUDE study, the first study large enough to permit subgroup analysis in patients who receive inappropriate shocks for different heart rhythms. The ALTITUDE results go a long way toward solving a mystery that has puzzled electrophysiologists in recent years: Why do the landmark clinical trials of implantable cardioverter defibrillator (ICD) therapy and cardiac resynchronization therapy plus defibrillation (CRT-D) consistently show that inappropriate shocks are associated with decreased survival, compared with no shocks?
"In this study, the adverse prognosis following an ICD shock may likely be related to the underlying arrhythmia and its associated disease process rather than to an adverse effect from the shock itself," Dr. Brian Powell explained in presenting the ALTITUDE data at the annual meeting of the Heart Rhythm Society.
SOURCE: Internal Medicine News