Abstract
BackgroundIn patients with cardiac resynchronization therapy (CRT), atrial fibrillation (AF) is associated with an unfavorable outcome and may cause loss of biventricular pacing (BivP). An effective delivery of BivP of more than 98% of all ventricular beats has been shown to be a major determinant of CRT-success.MethodsAt a Swedish tertiary referral center, data was retrospectively obtained from patient registers, medical records and preoperative electrocardiograms. Data regarding AF and BivP during the first year of follow-up was assessed from CRT-device interrogations. No intra-cardiac electrograms were studied. Kaplan-Meier curves and Cox-regression analyses adjusted for age, etiology of heart failure, left ventricular ejection fraction, left bundle branch block and NYHA class were performed to assess the impact of AF and BivP on the risk of death or heart transplantation (HTx) at 10-years of follow-up.ResultsPreoperative AF-history was found in 54% of the 379 included patients and was associated with, but did not independently predict death or HTx. The one-year incidence of new device-detected AF was 22% but not associated with poorer prognosis. At one-year, AF-history and BivP≤98%, was associated with a higher risk of death or HTx compared to patients without AF (HR 1.9, 95%CI 1.2–3.0, p = 0.005) whereas AF and BivP> 98% was not (HR 1.4, 95%CI 0.9–2.3, p = 0.14).ConclusionsIn CRT-recipients, AF-history is common and associated with poor outcome. AF-history does not independently predict mortality and is probably only a marker of a more severe underlying disease. BivP≤98% during first-year of CRT-treatment independently predicts poor outcome thus further supporting the use of 98% threshold of BivP, which should be attained to maximize the benefits of CRT.
Highlights
In patients with cardiac resynchronization therapy (CRT), atrial fibrillation (AF) is associated with an unfavorable outcome and may cause loss of biventricular pacing (BivP)
Manual assessment of all available ECGs prior to CRT implantation among all patients without AF history according to the Swedish National Patient Register (SNPR) or medical records (n = 190) revealed further 17 AF-cases and after combining the three sources 206 patients (54%) had preoperative AF history
Patients with AF had a higher likelihood of being treated with digoxin, warfarin or class I or III antiarrhythmic drugs and they were more often treated with a conventional pacemaker before CRT treatment
Summary
In patients with cardiac resynchronization therapy (CRT), atrial fibrillation (AF) is associated with an unfavorable outcome and may cause loss of biventricular pacing (BivP). An effective delivery of BivP of more than 98% of all ventricular beats has been shown to be a major determinant of CRT-success. There is a strong evidence that cardiac resynchronization therapy (CRT) reduces mortality and morbidity in patients with chronic heart failure (HF), depressed left ventricular ejection fraction (LVEF), widened QRS-complex and signs of electrical dyssynchrony in patients with sinus rhythm (SR) [1, 2]. An effective delivery of biventricular pacing (BivP) has been shown to be a major determinant of the success of CRT [4] and AF may cause loss of BivP [7]. Previous studies have defined high BivP as > 98% of all ventricular beats and in large-scale studies, the greatest magnitude of reduction in mortality has been observed in patients with a BivP achieved in excess of 98% [8, 9]
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