Cardiology News /Recent Literature Review / First Quarter 2014

Abstract

Athens Cardiology Update 2014: Athens (Crown Plaza Hotel), 10-12/4/2014

HRS Meeting: San Francisco, 7-10/5/2014

EuroPCR: Paris, 20-23/5/2014

CardioStim: Nice, 18-21/6/2014

ESC Congress: Barcelona, 30/8-3/9/14

TCT: Washington, 12-17/9/14

HCS Annual Meeting: Athens, 23-25/10/2014

AHA: Chicago, 15-19/11/14

Cutting Inappropriate ICD Shocks: Long Arrhythmia-Detection Time Strategy Confirmed

            Programming implantable cardioverter defibrillators (ICDs) to delay the time they take to treat ventricular arrhythmias cuts mortality by 23% and inappropriate shocks by more than one-half in a meta-analysis encompassing ~4900 patients. The included studies were prospective and multicenter and covered both primary and secondary prevention and patients with either ischemic or nonischemic cardiomyopathy. The risk of syncope did not rise significantly with longer detection times, despite traditional concerns that lots of patients would not tolerate prolonged arrhythmia exposure before their ICD is allowed to deliver therapy, either shocks or antitachycardia pacing (ATP). Instead, the extra time frequently gave devices a better chance to exclude non–life-threatening arrhythmias like atrial fibrillation and to let otherwise self-terminating ventricular arrhythmias play out on their own. Current nominal settings used by some ICD manufacturers are likely to be too aggressive, with arrhythmia detection times that in some cases may be as short as 1-3 s. These results highlight the importance of setting longer default ICD detection times. The analysis included 4896 patients from the MADIT-RIT, ADVANCE 3, and PROVIDE randomized trials and the RELEVANT nonrandomized study. Overall, 264 patients received appropriate shocks and 253 experienced inappropriate shocks at follow-up (12 - 17 months). The relative risk (RR) of death from any cause was 0.77 (p=0.02) in the prolonged-detection-time groups compared with controls; the risks of inappropriate shocks and appropriate and inappropriate ATP also fell significantly. Why there were fewer deaths with longer detection times is unclear but it may derive from less exposure to potential hazards of shocks and ATP; inappropriate shocks may up mortality, and ATP poses a small risk of inducing ventricular fibrillation; or it may be due to some other factor, e.g. avoidance of treatment for multiple ICD therapies (e.g., prescription of antiarrhythmic drugs) (Scott PA et al, Heart Rhythm 2014; DOI:10.1016/j.hrthm.2014.02.009. Epub 2014 Feb 12)... (excerpt)