chapter  34
Cardiac Resynchronization Therapy
Pages 6

The inclusion criteria for clinical trials have been relatively narrow.As a result, the data are convincing for the current U.S. Food and Drug Administration labeling criteria: New York Heart Association (NYHA) functional class III or IV, wide QRS, normal sinus rhythm, and biventricular pacing configuration. Clinical trial data have led to the following class IIa indication: biventricular pacing in patients with medically refractory, symptomatic NYHA class III or IV who have idiopathic dilated or ischemic cardiomyopathy, prolonged QRS interval (≥130 milliseconds), left ventricular end-diastolic diameter 55 mm or more, and ejection fraction 35% or less.