The Heart Failure Society of America's Guideline Committee updated its guidelines for cardiac resynchronization therapy (CRT), concluding that evidence supports the use of CRT in patients with less severe heart failure (HF) symptoms. The guideline update appeared in the February issue of the Journal of Cardiac Failure .
“The totality of the evidence supports the use of CRT in heart failure patients with reduced left ventricular ejection function (LVEF) across the spectrum of mild to severe symptoms,” senior author Randall C. Starling, MD, MPH, of the department of cardiovascular medicine at the Cleveland Clinic, said in a statement. “The evidence is most compelling among patients with an electrocardiogram QRS duration greater than or equal to 150 ms (normal being less than 100 ms).”
The authors noted that ample evidence supported the use of CRT in NYHA functional Class III and ambulatory Class IV patients at the time that the 2010 guideline update was under way but that clinical data had just begun to emerge for NYHA Class I and II patients. The authors undertook the task of examining recent clinical evidence in this patient group to re-evaluate CRT indications and provide more current guidance to physicians.
Their review included three randomized clinical trials of patients with less severe heart failure symptoms—REVERSE, MADIT-CRT and RAFT—and several meta-analyses. They highlighted a meta-analysis that showed a reduction in death and hospitalizations with CRT in patients with QRS duration greater than or equal to 150 ms, but no benefit with CRT in patients with QRS duration of less than 150 ms (Arch Intern Med 2011;171:1454-1462). The results informed their decision to incorporate the magnitude of QRS prolongation into clinical decisions involving CRT.
Under their changes, they recommended CRT for patients in sinus rhythm with a widened QRS interval (greater or equal to 150 ms) that is not due to right bundle branch block who have LVEF of 35 percent or less and persistent NYHA functional Class II–III symptoms despite optimal medical therapy (strength of evidence A).
They wrote that CRT may be considered for:
- Ambulatory NYHA functional Class IV patients with QRS equal or less than 150 ms and LVEF of 35 percent or less despite optimal medical therapy (strength of evidence B);
- NYHA functional Class II to ambulatory Class IV patients with a QRS greater or equal to 120 ms but less than to 150 ms and LVEF of 35 percent or less despite optimal medical therapy (strength of evidence B); and
- NYHA functional Class II-III atrial fibrillation patients with QRS greater or equal to 120 ms, and LVEF of 35 percent or less despite optimal medical therapy (strength of evidence B).
Starling and colleagues pointed out that there remain several gaps in the evidence that some ongoing trials may fill, requiring more modifications of the recommendations. They listed optimal patient selection as a pressing need. “Current patient selection is based on clinical trial eligibility criteria and findings from subgroup analyses, but identification of patients who will and will not respond to CRT needs to be further refined by rigorous scientific data,” they wrote.
They added that the clinical benefits in QRS durations between 120 ms and 150 ms remain unclear, along with QRS morphology, lead placement, degree of myocardial scarring and the best approach to evaluating dyssynchrony. They concluded with recommendations for strengthening CRT research.
The CRT guideline update is available here.