NEW YORK (Reuters Health) – Upgrading traditional 2 chamber cardiac pacemakers to modern 3 chamber pacemakers — cardiac resynchronization therapy (CRT) devices — improves left ventricular ejection fraction (LVEF), researchers reported online March 16th in the European Heart Journal.
Chronic right ventricular (RV) pacing with the older devices produces ventricular dyssynchrony, leading to LV remodeling and associated morbidity and mortality, the researchers note.
“The important clinical finding in our study is that even after a long period (up to 8 years) of 2 chamber pacing and subsequently very reduced LVEF, upgrading to CRT can improve systolic heart function,” senior author Dr. Johannes Holzmeister told Reuters Health by email.
Dr. Holzmeister of University Hospital Zurich and colleagues studied 102 patients after primary CRT implantation and 70 after a CRT upgrade.
After a mean follow-up of close to 2 years, the researchers saw significant absolute increases in LVEF of 10% in the primary group and 11% improvement in the upgrade group.
Both sets of patients had significant and similar reductions in LV end-systolic diameter and diameter index. The response to CRT upgrade was independent of the underlying rhythm, QRS duration, duration of prior RV pacing, or LV function and size at baseline.
Moreover, 7 of 9 patients with older devices in place for more than 12 years responded favorably to CRT.
“In other words,” concluded Dr. Holzmeister, this means “that a pacing induced cardiomyopathy is reversible even at a late stage.”
Eur Heart J 2010.