Comparison of verapamil versus felodipine on heart rate variability in hypertensive patients.
OBJECTIVE
We evaluated the effect of two calcium channel blockers, verapamil and felodipine, on heart rate variability in hypertensive patients.


METHODS
Time and frequency domain measures of heart rate variability were obtained from 24 h Holter recording in 25 previously untreated hypertensive patients without left ventricular hypertrophy, before and after 3 months of verapamil slow-release treatment (240 mg once daily) or felodipine extended-release treatment (10 mg once daily).


RESULTS
Blood pressure values decreased with both drugs. Measures of heart rate variability, comparable at baseline in the two groups, were unchanged after felodipine. After verapamil, the average RR interval, the square root of the mean of the squared differences between all adjacent normal RR intervals (r-MSSD) and the percentage of differences between all adjacent normal RR intervals > 50 ms (pNN50), measures of vagal modulation of heart rate, increased (from 735 +/- 67 to 827 +/- 84 ms, P < 0.001; from 30 +/- 10 to 44 +/- 15 ms, P < 0.001; and from 3 +/- 2 to 7 +/- 6%, P < 0.01, respectively) and were higher than after felodipine. The coefficient of variation, a measure that compensates for heart rate effects, increased only after verapamil (from 5.8 +/- 1.3% to 6.6 +/- 1.0%; P < 0.05). High frequency power and its coefficient of component variance, both representing the vagal modulation of heart rate, increased after verapamil (from 5.33 +/- 0.29 to 5.80 +/- 0.27 In units, P < 0.001 and from 1.9 +/- 0.3 to 2.2 +/- 0.25%; P < 0.05). Finally, the low to high frequency power ratio, an indicator of sympathovagal balance, with a high value suggesting a sympathetic predominance, decreased after verapamil (from 2.16 +/- 0.41 to 1.36 +/- 0.35; P < 0.001), confirming the improvement in vagal modulation of heart rate.


CONCLUSIONS
In hypertensive patients, despite a comparable anti-hypertensive effect, verapamil, but not felodipine, has favourable effect on cardiac autonomic control.
Institute of Internal Medicine, Cardiology and Heart Surgery, University of Naples Federico II, Italy.
M
M
Petretta
V
V
Canonico
A
A
Madrid
M
M
Mickiewicz
L
L
Spinelli
F
F
Marciano
A
A
Vetrano
A
A
Signorini
D
D
Bonaduce
D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D003692:Delayed-Action Preparations; D015736:Felodipine / Q000494:pharmacology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D006973:Hypertension / Q000188:drug therapy / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D016037:Single-Blind Method; D013997:Time Factors; D014700:Verapamil / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D003692:Delayed-Action Preparations; D014700:Verapamil; D015736:Felodipine