Predicting appropriate therapies and mortality in implantable cardioverter-defibrillator recipients: a work in progress.

Abstract

657 CRT reduces ventricular arrhythmias via reverse remodeling or whether resynchronization and shortening ventricular activation time confers a persistent antiarrhythmic effect.8 The MADIT\xad \xadCRT and a recent meta \xadanalysis8-10 provide ev\xad idence that CRT \xadmediated left ventricular im\xad provement is antiarrhythmic. In the absence of reverse remodeling, CRT with left ventricular epi\xad cardial stimulation may be proarrhythmic.11 Re\xad cent data suggest that CRT may be antiarrhyth\xad mic in primary prevention recipients and proar\xad rhythmic in secondary prevention recipients.8 The authors of the study stated that “in the long \xadterm follow \xadup, previous myocardial infarction was also predictor of ICD interven\xad tions.”1 It is tempting to speculate that ongo\xad ing ischemia could explain this finding. Never\xad theless, this differs from a 2010 study that re\xad ported no significant difference in the incidence of appropriate ICD shocks in patients with isch\xad emic versus nonischemic cardiomyopathy at the 33 \xadmonth follow \xadup.12 Winkler et al1 correctly noted that understand\xad ing the relationship between severe mitral regur\xad gitation and appropriate device therapy is chal\xad lenging. The major causes of severe mitral regur\xad gitation include primary valvular diseases (most commonly mitral valve prolapse)13 and second\xad ary (functional) valvular dysfunction due to coro\xad nary artery disease or cardiomyopathy.14 The pre\xad cise relationship between mitral valve prolapse and SCD remains uncertain and the increased SCD risk may be related to the valvular regurgi\xad tation rather than the abnormality in the valve’s structural apparatus.15 While secondary mitral regurgitation is associated with poor prognosis beyond the degree of left ventricular dysfunc\xad tion, survival rates vary inversely with mitral re\xad gurgitation severity,16 and death may be related to hemodynamic failure or a sudden arrhythmic In this issue of Polish Archives of Internal Medicine (Pol Arch Intern Med), Winkler et al1 identify pre\xad dictors of mortality and appropriate interventions in implantable cardioverter \xaddefibrillator (ICD) re\xad cipients. This is important because the extent to which individual patients benefit from an ICD varies considerably.2 The study group included primary and second\xad ary prevention device recipients. It is unsurpris\xad ing that secondary prevention patients received more appropriate ICD interventions for ventric\xad ular arrhythmias. Although some programming features are noted, there is no breakdown of ther\xad apies into antitachycardia pacing (ATP) and shock delivery. Taken as a group, patients who received shocks had higher ventricular arrhythmia bur\xad den and poorer survival than patients treated only with ATP.3 In the SCD\xadHeFT (Sudden Car\xad diac Death in Heart Failure Trial) post hoc anal\xad ysis, shocks (appropriate or not) were associat\xad ed with poorer survival in patients with ICDs.4,5 This has spurred interest in shock reduction with\xad out increasing syncope or sudden cardiac death (SCD) rates. Shocks can be reduced by appropriate programming,4,6 allowing longer detection times and longer arrhythmia duration before shock de\xad livery. The MADIT \xadRIT (Multicenter Automatic Defibrillator Implantation Trial – Reduce Inap\xad propriate Therapy) demonstrated that such pro\xad gramming can be associated with improved pa\xad tient survival.4,7 Strategic programming of ICD tachycardia detection and therapies is therefore recommended.4,6 Although Winkler et al1 found that cardiac re\xad synchronization therapy (CRT) reduced the risk of appropriate ICD therapy in primary prevention, the influence of CRT on ventricular arrhythmias is uncertain. While some studies suggest a proar\xad rhythmic effect, others suggest an antiarrhythmic effect. In particular, it remains unclear whether EDITORIAL