Author + information
- Received March 7, 1989
- Revision received May 24, 1989
- Accepted June 7, 1989
- Published online November 15, 1989.
- J.Thomas Bigger Jr., MD, FACC1,∗,
- Maria Teresa La Rovere, MD†,
- Richard C. Steinman, AB∗∗∗,
- Joseph L. Fleiss, PhD∗∗∗,
- Jeffrey N. Rottman, MD∗∗∗,
- Linda M. Rolnitzky, MS∗∗∗ and
- Peter J. Schwartz, MD, FACC‡
- ↵1Address for reprints: J. Thomas Bigger, Jr., MD, Division of Cardiology, Columbia University, 630 West 168th Street, New York, New York 10032. USA
In animals, baroreflex sensitivity is inversely related to the likelihood of ventricular fibrillation during myocardial ischemia. After myocardial infarction in human patients, reduced baroreflex sensitivity is associated with increased mortality. A reduced standard deviation of normal RR intervals over a 24 h period is also associated with reduced survival after myocardial infarction. Therefore, 32 normotensive men who had survived their first myocardial infarction were studied to define the relation between baroreflex sensitivity assessed with phenylephrine injection and three Hotter electrocardiographic measures of tonic vagal activity: the percent of successive normal RR intervals >50 ms, the root mean square successive difference of normal RR intervals and the power in the high frequency energy of the normal RR interval power spectrum.
Correlations among the Holter measures of heart period variability were ≥0.94, indicating that these measures are so strongly correlated that any one of them can be used to represent the others. Baroreflex sensitivity showed weaker correlations with the three Holter variables (0.57 to 0.63), indicating that the Holter measures did not accurately predict baroreflex sensitivity. Baroreflex sensitivity showed a stronger correlation with the three Hotter variables during the night than during the day. Baroreflex sensitivity and tonic vagal activity reflected by Holter variables were reduced more in patients with inferior myocardial infarction than in those with anterior infarction. The relative utility of baroreflex sensitivity and Holter measures of tonic vagal activity in predicting sudden cardiac death after myocardial infarction needs to be evaluated in a large prospective study.
☆ This study was supported in part by Grants HL-41552 and HL-70204 from the National Heart, Lung, and Blood Institute, National Institutes of Health and by Grant RR-00645 from the Research Resources Administration, Bethesda, Maryland and by funds from the Henry and Shirley Benach Foundation, New York, New York.
- Received March 7, 1989.
- Revision received May 24, 1989.
- Accepted June 7, 1989.