title: Effect of beta blockade on ventricular fibrillation- and ventricular tachycardia-induced circulatory arrest in acute myocardial infarction.
abstract: The risk of developing circulatory arrest secondary to ventricular fibrillation or tachycardia in acute myocardial infarction (AMI) is greatly increased in patients with hypokalemia, whether diuretic induced or not. In a retrospective study of 5,877 infarctions during an 8-year period, hypokalemia was more common (22.5%) in diuretic-treated AMI patients than in those not treated with diuretics (12.9%). Thus, hypokalemia should be avoided in diuretic-treated patients with increased risk of myocardial infarction. Circulatory arrest occurred in 13% of hypokalemic patients treated with nonselective beta blockers on admission compared with 26% in those treated with selective beta blockers. No difference was found in normokalemic patients. The mean serum potassium value was 4.07 mM/liter in the patients treated with nonselective beta blockers compared with 4.0 and 4.01 in those treated with selective and no beta blockade, respectively. In a separate study, adrenaline infusion in healthy volunteers produced a decrease not only in serum potassium but also in serum magnesium, although the latter occurred later. Pretreatment with verapamil exaggerated the decrease in serum potassium. When starting beta-blocker treatment in patients at risk of developing AMI, consideration should be given to commencing with a nonselective instead of a selective beta blocker.
authors.forename: B W
authors.initials: BW
authors.lastname: Johansson
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000368:Aged; D004232:Diuretics / Q000627:therapeutic use; D005260:Female; D006323:Heart Arrest / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D006801:Humans; D007008:Hypokalemia / Q000150:complications / Q000188:drug therapy; D008297:Male; D009203:Myocardial Infarction / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D011188:Potassium / Q000097:blood; D012189:Retrospective Studies; D013610:Tachycardia / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D014693:Ventricular Fibrillation / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology
chemical_list: D000319:Adrenergic beta-Antagonists; D004232:Diuretics; D011188:Potassium