• Martin H Ruwald, Ken Okumura, Takeshi Kimura, Kazutaka Aonuma, Morio Shoda, Valentina Kutyifa, Anne-Christine H Ruwald, Scott McNitt, Wojciech Zareba, and Arthur J Moss.
• Heart Research Follow-up Program, University of Rochester Medical Center, Rochester, NY (M.H.R., V.K., A.-C.H.R., S.M., W.Z., A.J.M.); Department of Cardiology, Gentofte Hospital, Hellerup, Denmark (M.H.R., A.-C.H.R.); Department of Cardiology, Hirosaki University Hospital, Hirosaki, Japan (K.O.); Department of Cardiology, Kyoto University Hospital, Kyoto, Japan (T.K.); Department of Cardiology, Tsukuba University Hospital, Tsukuba, Japan (K.A.); and Department of Cardiology, Tokyo Women's Medical University, Tokyo, Japan (M.S.).
• Circulation. 2014 Feb 4; 129 (5): 545-52.

BackgroundThere is a relative paucity of studies investigating the mechanisms of syncope among heart failure patients with implantable cardioverter-defibrillators, and it is controversial whether nonarrhythmogenic syncope is associated with increased mortality.Methods And ResultsThe Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate Therapy (MADIT-RIT) randomized 1500 patients to 3 different implantable cardioverter-defibrillator programming arms: (1) Conventional programming with therapy for ventricular tachycardia ≥170 bpm; (2) high-rate cutoff with therapy for ventricular tachycardia ≥200 bpm and a monitoring zone at 170 to 199 bpm, and (3) prolonged 60-second delay with a monitoring zone before therapy. Syncope was a prespecified safety end point that was adjudicated independently. Multivariable Cox models were used to identify risk factors associated with syncope and to analyze subsequent risk of mortality. During follow-up, 64 of 1500 patients (4.3%) had syncope. The incidence of syncope was similar across the 3 treatment arms. Prognostic factors for all-cause syncope included the presence of ischemic cardiomyopathy (hazard ratio [HR], 2.48; 95% confidence interval [CI], 1.42-4.34; P=0.002), previous ventricular arrhythmias (HR, 2.99; 95% CI, 1.18-7.59; P=0.021), left ventricular ejection fraction ≤25% (HR, 1.65; 95% CI, 0.98-2.77; P=0.059), and younger age (by 10 years; HR, 1.25; 95% CI, 1.00-1.52; P=0.046). Syncope was associated with increased risk of death regardless of its cause (arrhythmogenic syncope: HR, 4.51; 95% CI, 1.39-14.64, P=0.012; nonarrhythmogenic syncope: HR, 2.97; 95% CI, 1.07-8.28, P=0.038).ConclusionsInnovative programming of implantable cardioverter-defibrillators with therapy for ventricular tachycardia ≥200 bpm or a long delay is not associated with increased risk of arrhythmogenic or all-cause syncope, and syncope caused by slow ventricular tachycardias (<200 bpm) is a rare event. The clinical risk factors associated with syncope are related to increased cardiovascular risk profile, and syncope is associated with increased mortality irrespective of the cause.Clinical Trial Registration Urlhttp://www.clinicaltrials.gov. Unique identifier: NCT00947310.

25 keywords...

hide…