Electrical devices for left ventricular dysfunction and heart failure: do we need revised guidelines?

Abstract

Three recent trials have demonstrated the benefit of cardiac resynchronization therapy (CRT) in the New York Heart Association (NYHA) class II patients with heart failure (HF) with ischemic or nonischemic cardiomyopathy as well as in NYHA class I (asymptomatic) patients mostly with ischemic cardiomyopathy. Earlier intervention with CRT in asymptomatic or minimally symptomatic patients improves survival and reduces HF hospitalizations. The reduction or the prevention of HF hospitalizations is of paramount importance because the HF episodes seem to alter the natural history of disease and are associated with deterioration of left ventricular (LV) function and a marked increase in mortality. The CRT benefit is greatest in patients with a QRS ≥ 150 ms. At this time, it would seem prudent to consider CRT-D (D = ICD) therapy for class I NYHA patients with a QRS ≥ 150 ms and an LV ejection fraction ≤ 30% regardless of etiology. Although the data for NYHA class I patients with nonischemic cardiomyopathy are scanty, the recommendation for class I patients is justified because CRT achieves a much greater degree of LV reverse remodeling in nonischemic compared to ischemic patients. With regard to lone ICDs, there is no evidence that they prevent sudden cardiac death more efficiently in symptomatic than in asymptomatic patients. Cardiomyopathy should be the primary target for device therapy regardless of symptoms for both CRT and lone ICD therapy. New guidelines are needed to address the role of CRT in hospitalized NYHA class IV HF patients or those who depend on inotropic therapy or an LV assist device because randomized CRT trials have not included these patients. CRT in these patients remains controversial. The mortality of such patients even with CRT is very high despite the occasional positive response. The role of CRT in patients waiting for cardiac transplantation also needs guidelines. With the expansion of CRT indications to minimally symptomatic or asymptomatic patients, the benefit of device therapy must be carefully weighed against the potential risk of lifelong device complications.