A prospective evaluation of the effect of simvastatin on heart rate variability in non-ischemic cardiomyopathy.
BACKGROUND
Modulation of sympathetic tone may contribute to statin-mediated reduction in sudden cardiac death. We examined the effect of simvastatin on heart rate variability (HRV) in patients with non-ischemic dilated cardiomyopathy to evaluate for an antisympathetic effect of statins independent of anti-ischemic properties.


METHODS
The study was a prospective, open-label, self-controlled trial. Frequency domain analysis of HRV was assessed in 25 patients with non-ischemic dilated cardiomyopathy at baseline and after a 6-week course of simvastatin. The primary end point was the change in 5-minute sitting total spectral power (TSP) as a composite measurement of autonomic nervous system modulation. Secondary end points included the change in respiratory frequency area (RFa) with deep breathing (parasympathetic stress) and in low-frequency area (LFa) with Valsalva (sympathetic stress).


RESULTS
Simvastatin had no effect on 5-minute sitting TSP (baseline 1932 +/- 1165 vs posttreatment 2570 +/- 1877 square milliseconds, P = .770), RFa with deep breathing (baseline 19 +/- 7 vs posttreatment 14 +/- 4 [beat/min]2, P = .31), or LFa with Valsalva (baseline 26 +/- 6 vs posttreatment 32 +/- 8 [beat/min]2, P = .342). Bivariate analysis demonstrated no correlation between low-density lipoprotein (LDL) change and change in TSP or RFa, but did demonstrate an inverse relationship between change in LDL and change in LFa with Valsalva stress (r = -0.45 and P = .041).


CONCLUSIONS
Although simvastatin did not change baseline HRV, a modest relationship exists between the extent of LDL reduction and sympathetic responsiveness to stress.
Gentlesk
Philip J
PJ
Cardiology Service, Walter Reed Army Medical Center, Washington, DC 20307-5001, USA.
Wiley
Thomas
T
Taylor
Allen J
AJ
D002311:Cardiomyopathy, Dilated / Q000188:drug therapy* / Q000503:physiopathology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D019821:Simvastatin / Q000627:therapeutic use*; D013564:Sympathetic Nervous System / Q000187:drug effects
D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D019821:Simvastatin