Disappointing results for MASCOT trial
ONE-YEAR RESULTS from the 409-patient Management of Atrial Fibrillation Suppression in AF-HF Comorbidity Therapy (MASCOT) trial, presented during a late-breaking clinical trials session of the American Heart Association Scientific Sessions 2007, Orlando, FL, have shown that the incidence of permanent Atrial Fibrillation in the control group was much lower (3.3%, representing six patients) than anticipated. The MASCOT trial was designed to determine whether the AF Suppression pacing (developed by St Jude Medical) algorithm prevents permanent AF – the most severe stage of AF – in patients receiving cardiac resynchronization therapy (CRT). This AF Suppression algorithm already has been shown to decrease symptoms of paroxysmal AF (where patients experience episodes of AF) in certain pacemaker patients. MASCOT was a European multi-centre, prospective randomised trial designed to evaluate the development of AF in CRT patients. The incidence of permanent AF was also low, 3.3% (seven patients), in the study group. The low incidence in both groups made it difficult to measure the impact, or to draw conclusions, about AF Suppression therapy’s effects in this subgroup of heart failure patients. Based on previous studies, the incidence of permanent AF in the control group was expected to be 8 to 9%. Importantly, however, the study showed the AF Suppression algorithm is safe in these patients and does not impair patient response to CRT, confirming the results observed in a previous investigational device examination (IDE) clinical study. “The historic incidence of permanent AF in heart failure patients is around 9 percent, but in our trial the surprisingly small percentage of patients with this condition complicated our efforts to assess the benefits of AF Suppression treatment,” said Professor Luigi Padeletti, Professor of Cardiology and Director of the Postgraduate School of Cardiology, University of Florence, Italy, who was the principal investigator in the study. “Still, we are encouraged by the positive safety signal observed, and we continue to believe that this approach may represent a major advance in the treatment of AF and heart failure by electrical stimulation.” The MASCOT study was a single-blind, controlled clinical trial that enrolled two groups of patients, all of whom received CRT with a St Jude Medical device. Most patients had severe (NYHA Class III) heart failure, and 19 percent had a history of paroxysmal AF. The active group had the devices programmed with the AF suppression algorithm; that algorithm was turned off in the control group. Patients will be followed for an additional year to evaluate the incidence of permanent AF at two years.
