Cardiac Resynchronization Therapy for Mild Heart Failure The Time Has Come

Current guidelines recommend cardiac resynchronization therapy (CRT), previously known as biventricular pacing, in patients with left ventricular (LV) systolic dysfunction (ejection fraction [EF] ≤35%), QRS prolongation (≥120 ms), and New York Heart Association (NYHA) class III or IV heart failure (HF).1 These recommendations come after multiple prospective, randomized trials demonstrated the benefits of CRT in advanced HF that included >6000 subjects. These initial trials targeted secondary prevention in the highest-risk cohorts, which was similar to the development of many other cardiovascular therapies. Such examples include implantable cardioverter-defibrillator (ICD) therapy initially used only for cardiac arrest survivors or lipid-lowering therapy restricted to use after myocardial infarction. Today a majority of patients receive these therapies as primary prevention. Thus, it is logical and not surprising that a therapy as successful as CRT would be evaluated in subjects with mild HF. Two such studies were published recently: the Resynchronization Reverses Remodeling in Systolic Left Ventricular Dysfunction (REVERSE) study and the Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy (MADIT-CRT).2–5 Taken together, these trials randomized 2430 subjects with NYHA class I or II HF to CRT or to no CRT. The results show beneficial effects of CRT very similar to those observed for severe HF cohorts. Specifically, this therapy improves functional status, reduces HF hospitalizations, and promotes reverse remodeling. The results from REVERSE and MADIT-CRT provide strong, new support to expand the use of CRT to all patients with HF and a wide QRS. Strong evidence exists to support the ability of CRT to cause LV reverse remodeling; specifically, decreased LV end-systolic volume (ESV) and end-diastolic diameter, increased LV EF, and decreased mitral valve regurgitation are observed.6 Most importantly, data also demonstrate reduction in HF hospitalizations and all-cause morbidity and mortality with long-term follow-up.7–9 Response …