DALLAS – Enhanced pacemaker technology sharply reduced progression of nonpermanent atrial fibrillation to permanent AF in patients with bradycardia and sinus node disease in the large international, randomized MINERVA trial.
In the MINERVA (Minimize Right Ventricular Pacing to Prevent Atrial Fibrillation and Heart Failure) study, the use of dual-chamber pacemakers containing features for atrial preventive pacing and atrial antitachycardia pacing, called DDDRPs, plus managed ventricular pacing (MVP) resulted in a 61% reduction in the incidence of permanent AF during 2 years of prospective follow-up, compared with conventional dual-chamber pacing, Dr. Giuseppe Boriani reported at the American Heart Association scientific sessions.
In addition, patients in the enhanced-pacing group experienced a 52% reduction in AF-related hospitalizations and emergency department visits, as well as a 49% decrease in atrial cardioversions relative to controls, added Dr. Boriani of the University of Bologna (Italy).
"This is the first study to show that using these enhanced pacing features in combination not only delays the AF disease progression, but also has an impact on health care utilization," he noted. "With this solid evidence of beneficial results, I think the practice guidelines probably should be updated to state this type of device should be implanted for sinus node disease in patients with a history of atrial fibrillation."
MINERVA included 1,166 patients at 63 European, Asian, and Middle Eastern centers; all had bradycardia, sinus node disease, and a history of nonpermanent AF. They received a commercially available Medtronic dual-chamber pacemaker that was randomized single-blind to operate using both the DDDRP and MVP features, the MVP alone, or conventional dual-chamber pacing with neither enhanced feature.
At 2 years, the primary composite endpoint of death, cardiovascular hospitalization, or permanent AF had occurred in 19.8% of the DDDRP plus MVP group. That amounted to a significant 26% reduction in the endpoint compared with the 26.5% rate in the controls on standard dual-chamber pacing. The 21.4% rate in patients whose device used only the MVP algorithm was not significantly different from the rate in controls.
Most strikingly, the 2-year incidence of progression to permanent AF was 3.8% in patients with the enhanced pacing features, compared with 9.2% in those assigned to conventional dual-chamber pacing, for a 61% relative risk reduction. This means 20 patients would need to be treated for 2 years with a pacemaker utilizing the advanced pacing features in order to prevent one additional case of permanent AF.
In addition, patients whose pacemakers utilized rate response and antitachycardia pacing plus MVP reported better quality of life and less fatigue than did those in the other two study arms.
Dr. Boriani estimated that of the 170,000 patients each year in the United States who undergo pacemaker implantation for bradycardia, roughly 25,000 have sinus node disease and a history of AF and would thus now be considered strong candidates for the enhanced pacing features.
Discussant Dr. Anthony Tang explained that it has been known for years that pacemaker algorithms designed to increase the atrial pacing rate above the intrinsic sinus rate can prevent events that trigger AF. The problem has been that this atrial pacing can have the side effect of also increasing ventricular pacing, which can initiate AF, thus canceling the advantage of the atrial preventive pacing. The MVP algorithm decreases this unnecessary pacing in the right ventricle, with the resultant benefits seen in MINERVA.
In his view, the enhanced pacing features used in MINERVA represent a very good option for patients with severe sinus node dysfunction but preserved atrioventricular node conduction, that is, patients who need atrial pacing for long sinus pauses but don’t need much ventricular pacing.
In contrast, for patients with an indication for a pacemaker but who only occasionally need pacing, such as those with a rare sinus pause or occasional AV block, a simple single-chamber ventricular pacemaker will generally do. For those with second- or third-degree AV block with left ventricular dysfunction and who need both atrial and ventricular pacing most of the time, a cardiac resynchronization therapy device plus either a pacemaker or a defibrillator is appropriate, depending upon the severity of the left ventricular dysfunction, according to Dr. Tang, professor of medicine and chair of cardiovascular population health at Western University, London, Ont.
Discussant Dr. Timothy J. Gardner wasn’t bowled over by the number-needed-to-treat (NNT) of 20 in MINERVA.
"That seems a very modest impact. I wonder from a health care/societal benefit standpoint whether an NNT of 20 for a more complex and expensive technology is appropriate," challenged Dr. Gardner, a heart surgeon and medical director of the Christiana Care Center for Heart and Vascular Health in Newark, Del.