Chronic atrial fibrillation does not influence the magnitude of sympathetic overactivity in patients with heart failure

Abstract

In this study we sought to assess the influence of atrial fibrillation (AF) on sympathetic nervous system overactivity in congestive heart failure (CHF) patients. We studied 133 consecutive patients with moderate to severe CHF. Subjects underwent haemodynamic assessment (right heart catheterization) and assessment of total systemic and cardiac sympathetic activity by the norepinephrine (NE) spillover method. The study population included 108 patients in sinus rhythm (SR) and 25 in AF. While AF patients had a lower cardiac output (CO) (SR vs AF: 4.2+/-0.1 vs 3.7+/-0.2l/min, P<0.05), the groups were otherwise matched for systemic blood pressure (BP), heart rate and filling pressures. In conjunction, total body NE spillover (SR vs AF: 5.8+/-0.4 vs 4.9+/-0.5 nmol/min, P>0.05) and cardiac NE spillover (SR vs AF: 339+/-21 vs 393+/-49 pmol/min, P>0.05) were not significantly different between the two groups, while the systemic clearance rate for NE was lower in the AF group (SR vs AF: 2.2+/-0.1 vs 1.6+/-0.1l/min, P<0.05). Congestive heart failure patients in AF do not appear to have heightened sympathetic tone compared to CHF patients in SR.