Can cardiac resynchronization improve symptoms in some people with heart failure?

Details

Earlier studies suggested that cardiac resynchronization through atrial-synchronized biventricular pacing could benefit patients with heart failure and an intraventricular conduction delay. Researchers conducted a double-blind trial to evaluate this approach.

They randomly assigned 453 patients with moderate-to-severe heart failure symptoms, an ejection fraction of 35% or less and a QRS interval of at least 130 milliseconds to cardiac resynchronization (228 patients) or a control group (225 patients) for six months, while conventional heart failure therapy continued. The primary endpoints were New York Heart Association functional class, quality of life and distance walked in six minutes.

Compared with controls, patients assigned to cardiac resynchronization improved more in six-minute walking distance (+39 vs. +10 m, P=0.005), functional class (P<0.001), quality of life (-18.0 vs. -9.0 points, P=0.001), treadmill time during exercise testing (+81 vs. +19 seconds, P=0.001) and ejection fraction (+4.6% vs. -0.2%, P<0.001). Fewer patients assigned to cardiac resynchronization needed hospitalization (8% vs. 15%) or intravenous medication (7% vs. 15%) to treat heart failure, with P<0.05 for both comparisons.

Device implantation was unsuccessful in 8% of patients. Four patients experienced refractory hypotension, bradycardia or asystole during implantation, and two of them died; two other patients had coronary sinus perforation requiring pericardiocentesis. The researchers concluded that cardiac resynchronization produces significant clinical improvement in patients with moderate-to-severe heart failure and an intraventricular conduction delay.