Pacing to Avoid Cardiac Enlargement (PACE) trial conducted by Medtronic, Inc. (Medtronic) showed that bi-ventricular pacing can prevent cardiac enlargement as compared to only pacing the right ventricle in pacemaker patients with normal pumping hearts. The findings were presented at clinical science session at the Scientific Sessions 2009, the annual congress of the American Heart Association in Orlando, Florida.
Meeting its primary objective, PACE results showed that after one year of pacing, patients with pacing in both right and left ventricles (bi-ventricular) had no significant changes in left ventricle size while patients paced only in the right ventricle developed enlarged left ventricles. Adverse changes in patients paced only in the right ventricle included a significant increase of 6.3 milliliter on average in the size of the left ventricle at the end contraction, and a decrease of 6.8% in the ejection fraction, or the amount of available blood pumped from the left ventricle.
“These early results show bi-ventricular pacing may be superior to pacing only in the right ventricle to preserve the heart’s normal left ventricle size and pumping ability for these pacemaker patients,” said Cheuk-Man Yu, M.D. professor of medicine at Prince of Wales Hospital, The Chinese University of Hong Kong in China and PACE lead investigator. “As the first randomized study with this patient population, these initial results suggested that ensuring synchrony of the ventricles can help maintain patient health.”
“Clinical evidence shows delivering pacing only when and where patients need it is important to improving the care of pacemaker patients,” said Marshall Stanton, M.D., vice president of clinical research for the Cardiac Rhythm Disease Management business at Medtronic. “With the Medtronic-exclusive pacing mode MVP, Managed Ventricular Pacing, which is the only technology available that reduces unnecessary right ventricular pacing by 99%, and the ongoing BLOCK-HF bi-ventricular pacing study.”
The PACE study is a prospective, randomized, double-blind, parallel study enrolling 177 patients at four hospitals in Asia. Patients had a Medtronic Insync III cardiac resynchronization therapy-pacemaker (CRT-P), or bi-ventricular pacemaker without defibrillation, and had no prior history of heart failure with normal left ventricle function and ejection fraction greater than or equal to 45%. Patients were evaluated at one, three, six, nine and 12 months.