Cardiac resynchronization therapy : determinants of patient outcome and emerging indications

Abstract

CRT has evolved as a successful treatment strategy in selected patients with drug refractory heart failure. Evidence of large clinical trials established the beneficial effects of CRT in addition to optimal medical treatment on both morbidity and mortality. Nonetheless, about 30% of patients do not demonstrate response to CRT. Several patient characteristics have a strong influence on both response at 6 months follow-up and prognosis during long-term follow-up. In addition to these patient characteristics, the position of the LV pacing lead in relation to the site of latest activation and potential scar tissue may have a great influence on outcome. Integration of patient characteristics, LV lead position with information on LV dyssynchrony and scar tissue may help to improve patient selection and response to CRT. It is not unlikely that the favorable effects of CRT will be extended to other patient groups in the coming years. These groups include asymptomatic (NYHA class I) patients, patients with a narrow QRS complex (<120 ms) or patients with heart failure but preserved LVEF (__45%). CRT also seems to improve other conditions frequently observed in patients with heart failure. The improved LV systolic function induced by CRT increases cerebral blood flow and also results in stabilization of renal function. Finally, patients with severe functional MR and high operative risk also derive benefit from CRT. Perhaps CRT may one day be used as an effective treatment strategy in these patient groups