Successful implementation of guidelines for encouraging the use of beta blockers in patients after acute myocardial infarction

PURPOSE: To assess whether implementation of guidelines increases the prescription of drugs, particularly β blockers, recommended for secondary prevention after acute myocardial infarction. SUBJECTS AND METHODS: Prescription patterns among 355 patients discharged from a public teaching hospital after recovery from myocardial infarction were prospectively monitored in a before-after trial. The implementation strategies included educational interventions (large group meetings), placement of guidelines in patients’ records, and bimonthly general reminders sent to physicians. RESULTS: Beta blockers were prescribed in 93 (38%) of 243 survivors of acute myocardial infarction before guideline implementation (12-month control period), as compared with 71 (63%) of 112 patients (P<0.001) after their implementation (6-month period). During the entire study period, the prescription of β blockers at a neighboring public teaching hospital, used as a comparison, was unchanged. After adjusting for potential confounders, implementation of the guidelines remained significantly associated with prescription of β blockers at discharge [odds ratio (OR) = 10; 95% confidence interval (CI), 3.2 to 33; P<0.001]. Other independent predictors of prescription of β blockers were previous coronary artery bypass grafting (OR = 8.7; 95% CI, 2.5 to 31; P = 0.001), hypertension (OR = 2.5; 95% CI, 1.4 to 4.5; P = 0.003), age per 10-year increase (OR = 0.82; 95% CI, 0.67 to 0.99; P = 0.04), secular trend in prescription patterns expressed in months (OR = 0.9; 95% CI, 0.8 to 1.0; P = 0.02), a left ventricular ejection fraction ≤40% (OR = 0.2; 95% CI, 0.1 to 0.4; P<0.001), the presence of atrioventricular block (OR = 0.1; 95% CI, 0.02 to 0.7; P = 0.02), and concomitant prescription of digoxin (OR = 0.2; 95% CI, 0.05 to 0.8; P = 0.02) or calcium antagonists (OR = 0.06; 95% CI, 0.01 to 0.3; P = 0.001). CONCLUSION: When appropriately developed and implemented by local experts, literature-based guidelines may be effective in modifying use of recommended drugs for secondary prevention of coronary artery disease, such as prescription of β blockers.