Extramiana F, Maison-Blanche P, Tavernier R, Jordaens L, Leenhardt A, Coumel P. Cardiac effects of chronic oral beta-blockade: lack of agreement between heart rate and QT interval changes.
Ann Noninvasive Electrocardiol 2002;
7:379-88. [PMID:
12431318 PMCID:
PMC7027610 DOI:
10.1111/j.1542-474x.2002.tb00189.x]
[Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND
Although well established on the sinus node, the effects of beta-blockade on ventricular repolarization are still conflicting. The aim of the study was to investigate the effects of a chronic beta-blockade on sinus node and repolarization parameters and their relationship.
METHODS
Sixteen healthy volunteers (10 males, mean age: 40 +/- 6.7 years) were randomized to placebo or atenolol (100 mg). After 7 days, subjects were crossed over. Heart rate (HR) and HRV indices were calculated from long-term ECG recordings separately during the day and at night, together with ventricular repolarization parameters (QT interval duration and QT rate-dependence).
RESULTS
Mean R-R intervals were significantly and consistently increased after atenolol (Day: 916 +/- 103 ms vs. 712 +/- 89 ms, and Night: 1149 +/- 93 vs. 996 +/- 125 ms). HRV changes under atenolol were also consistent, with a significant decrease in sympathovagal ratio. In contrast, atenolol only lowered diurnal QT rate-dependence (0.123 +/- 0.032 vs. 0.190 +/- 0.065 on placebo, P < 0.001), but not the nocturnal pattern. After multivariate analysis QT rate-dependence changes induced by atenolol were correlated with pretreatment QT/RR relation (r = 0.65, P < 0.01) but not with any HR or HRV parameters.
CONCLUSIONS
In healthy subjects, repolarization changes following chronic beta-blockade cannot be predicted by HR or HRV changes, but are dependent on pretreatment rate-dependence.
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