Beneficial effect of candesartan treatment on cardiac autonomic nervous activity in patients with chronic heart failure: Simultaneous recording of ambulatory electrocardiogram and posture

Abstract Background : Reclining in the right lateral decubitus position in chronic heart failure (CHF) is a self‐protective mechanism for normalizing impaired cardiac autonomic nervous activity (CANA). Hypothesis : Candesartan, an angiotensin II receptor blocker, exerts beneficial effects on CANA and postural preferences in patients with CHF. Methods : We studied 15 patients with CHF due to coronary artery disease. Cardiac autonomic nervous activity was assessed using spectral heart rate variability (HRV) analysis based on 24‐h ambulatory electrocardiogram monitoring before and after an 8‐week treatment with candesartan. The patients' posture was simultaneously recorded using a specially devised detector, as the right (R) or left (L) lateral decubitus or supine (S) positions, to evaluate postural modulations of CANA. Normalized high‐frequency (0.15 to 0.40 Hz) power (nHF) and the low‐frequency (0.04 to 0.15 Hz)/high‐frequency power ratio (LF/HF) were used as indices of vagal activity and sympathovagal balance, respectively. Results : When HRV was analyzed in each position, CANA was changed in L and S, but not in R, from sympathetic to parasympathetic prevalence by the treatment (R, nHF, 50 ± 20 vs. 52 ± 19 nu, p = 0.87; LF/HF, 1.39 ± 1.11 vs. 1.32 ± 1.32, p = 0.93; L, nHF, 28 ± 13 vs. 47 ± 19 nu, p = 0.019; LF/HF, 3.34 ± 2.48 vs. 1.56 ± 1.39, p = 0.029; S, nHF, 38 ± 17 vs. 53 ±16 nu, p = 0.0023; LF/HF, 2.43 ± 2.21 vs. 1.03 ± 0.59, p = 0.025). The fractions of the time in R and L were decreased and increased, respectively, by the treatment (R, 40 ± 30 vs. 18 ± 24%, p = 0.0018; L, 11 ± 20vs. 27 ± 26%, p = 0.025). Conclusions : In patients with CHF, candesartan treatment improves cardiac autonomic balance, and the preference for the right lateral decubitus position disappears afterthe treatment.