Experimental data have indicated that baroreflex sensitivity is often depressed in dogs after myocardial infarction and that this depression correlates strongly with subsequent mortality during episodes of acute myocardial ischemia. This finding has several clinical implications. The present study was undertaken with the objectives of assessing the potential existence of differences in baroreflex sensitivity between men with and without myocardial infarction and the time course during the 1st year after infarction of these potential changes in baroreflex sensitivity. Fifty-three subjects entered the study: 32 postinfarction patients and 21 control subjects. Baroreflex sensivity was assessed by increasing mean blood pressure by aphenylephrine infusion (70 μg/ml) and recording the consequent RR interval changes. Baroreflex sensivity, expressed as the slope of the regression line relating mean blood pressure to RR interval changes, was evaluated 18 days (n = 32), 3 months (n = 17) and 13 months (n = 10) after infarction. Baroreflex sensitivity was lower in the patients than in the control subjects (8.2 ± 3.7 versus 12.3 ± 2.9 ms/mm Hg, p = 0.0001). Moreover, 13 (41%) of 32 patients had a baroreflex slope <6.5 ms/mm Hg, which was 2 SD below the mean value of the control subjects. The internal control follow-up study showed that baroreflex sensivitity increased 3 months after infarction to values quite similar to those observed in the control subjects (11.1 ± 5.3 versus 8.7 ± 3.5 ms/mm Hg, p = 0.02). No further change was observed between 3 and 13 months after myocardial infarction. These data indicate that baroreflex sensitivity is lower in a proportion of postinfarction patients than in control subjects. This transient depression of baroreflex sensitivity may relate to the reduced cardiac electrical stability present in the first few months after infarction.
|Number of pages||8|
|Journal||Journal of the American College of Cardiology|
|Publication status||Published - 1988|
ASJC Scopus subject areas