Table 1.

Inclusion and Exclusion Criteria

Inclusion Criteria	Exclusion Criteria
Previous diagnosis of chronic heart failure	Major cardiovascular event within 6 weeks before enrollment
Cardiac resynchronization therapy device implanted at least 6 months before enrollment	Uncontrolled hypertension
History of symptomatic congestive heart failure (NYHA functional class II–IV)	Inability to walk on treadmill
Prior ejection fraction <40% or documented moderate to severely impaired systolic dysfunction
Stable medical therapy for heart failure
>90% biventricular pacing

NYHA = New York Heart Association.