Benefits of non-selective versus cardioselective beta-blockers in acute myocardial infarction in hypertensive patients.
OBJECTIVE
To evaluate the effect of current treatment with non-selective or cardioselective beta-blockers on the outcome of a first acute myocardial infarction in hypertensive patients.


METHODS
Peak aspartate aminotransferase was measured as an indirect estimate of infarct size, the occurrence of circulatory arrest from ventricular tachyarrhythmias and in-hospital mortality.


METHODS
A retrospective analysis was performed on data collected in a continuously operating register of all hospitalized acute myocardial infarctions in Malmö, Sweden.


METHODS
A total of 2114 hypertensive patients were admitted to hospital with a first acute myocardial infarction. Of these patients, 323 were treated with a non-selective beta-blocker on admission and 338 with a cardioselective beta-blocker.


RESULTS
In patients given a non-selective beta-blocker the mean peak aspartate aminotransferase was 3.02 +/- 0.15 mukat/l, which was significantly lower than the peak (3.78 +/- 0.35 mukat/l) recorded in the patients given a cardioselective beta-blocker. In a multiple regression analysis, treatment with a non-selective beta-blocker was significantly and inversely related to peak aspartate aminotransferase after adjustment for several clinical characteristics. Age, anterior myocardial infarction, peak aspartate aminotransferase, serum potassium and treatment with a cardioselective beta-blocker were significantly and independently associated with the occurrence of circulatory arrest due to ventricular tachyarrhythmias. The relative risk of circulatory arrest in patients taking cardioselective beta-blockers was 1.73 (95% confidence interval 1.16-2.58) and in patients taking non-selective beta-blockers 1.02 (95% confidence interval 0.64-1.66). Advanced age, a history of diabetes mellitus, a history of stroke, anterior myocardial infarction, a high serum potassium level and a high peak aspartate aminotransferase level significantly predicted in-hospital mortality. The relative risk of in-hospital mortality in patients taking non-selective beta-blockers was 0.92 (95% confidence interval 0.64-1.30), and in patients taking cardioselective beta-blockers 0.84 (95% confidence interval 0.59-1.19).


CONCLUSIONS
The study suggests that current treatment with non-selective beta-blockers may have reduced the enzymatically estimated infarct size and the occurrence of circulatory arrest due to ventricular tachyarrhythmias. Both non-selective and cardioselective beta-blockers may also have reduced the in-hospital mortality in this population of hypertensive patients suffering a first acute myocardial infarction. In a clinical study using with adrenaline infusions in healthy volunteers, we found that beta 2-receptor blockade improved potentially arrhythmogenic variables, such as hypokalemia and hypomagnesemia, but the adrenaline-induced reduction in diastolic blood pressure was reversed. Pretreatment with the new beta-blocker carvedilol preserved the beneficial electrolyte effects without increasing blood pressure during the adrenaline infusion.
Hansen
O
O
Section of Cardiology, General Hospital, Malmö, Sweden.
Johansson
B W
BW
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology / Q000627:therapeutic use*; D000368:Aged; D001219:Aspartate Aminotransferases / Q000097:blood; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000188:drug therapy*; D012189:Retrospective Studies
D000319:Adrenergic beta-Antagonists; D001219:Aspartate Aminotransferases