Effect of atenolol and diltiazem on heart period variability in normal persons

James R. Cook, J. Thomas Bigger, Robert E. Kleiger, Joseph L. Fleiss, Richard C. Steinman, Linda M. Rolnitzky

Research output: Contribution to journalArticle

214 Scopus citations


Several time and frequency domain measures of heart period variability are reduced 1 to 2 weeks after myocardial infarction, and a reduced standard deviation of normal RR intervals over a 24 h period (SDNN) is associated with increased mortality. The predictive accuracy of heart period variability may be reduced by drugs used to treat patients after myocardial infarction. Accordingly, a randomized, three period, placebo-controlled, crossover (Latin square) design was used to determine the effect of atenolol and diltiazem on time and frequency measures of heart period variability calculated from 24 h continuous electrocardiographic recordings during treatment with atenolol, diltiazem and placebo in 18 normal volunteers. During atenolol treatment, the 24 h average normal RR (NN) interval increased 24% (p < 0.001). The three measures of tonic vagal activity were significantly increased (p < 0.001) during atenolol treatment: percent of successive normal RR intervals >50 ms = 69%, root mean square successive difference of normal RR intervals = 61% and high frequency power in the heart period power spectrum = 84%. Low frequency power also increased 45% (p < 0.01), indicating that this variable also is an indicator of tonic vagal activity over 24 h. Diltiazem had no significant effect on the 24 h average NN interval or on any measure of heart period variability. The decreased mortality rate after myocardial infarction associated with beta-adrenergic blocker but not calcium channel blocker therapy may be attributed in part to an increase in vagal tone caused by beta-blockers.

Original languageEnglish
Pages (from-to)480-484
Number of pages5
JournalJournal of the American College of Cardiology
Issue number2
StatePublished - Jan 1 1991
Externally publishedYes

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