Trends of prescribing patterns for the secondary prevention of myocardial infarction over a 13-year period

Objective: The efficacy of beta-adrenergic blocking agents and acetylsalicylic acid in the secondary prevention of myocardial infarction has been well recognized since the beginning of the 1980s. In a previous paper, however, we reported a lower than expected use of these drugs during the period 1982-1988. In 1989 the results of this survey were presented and discussed with the prescribing physicians. In the present paper we describe the prescription patterns for the same indication and in the same centre over the following 6 years (1989-1994). We also describe the use of angiotensin-converting enzyme (ACE) inhibitors, for which efficacy in certain subgroups has been recently shown. Methods: Random samples of patients discharged from our hospital between 1989 and 1994 with a diagnosis of acute myocardial infarction with Q-wave were studied. Information about diagnoses, other clinical variables and treatments prescribed at discharge was obtained from the hospital discharge forms. The results were compared with those obtained in the previous study. Results: We studied 514 patients (80% men) with a median age of 59 years (range 31-89). The proportions of patients prescribed beta-adrenergic blocking agents and acetylsalicylic acid increased from 34% and 28%, respectively, in 1986-1988, to 62% and 75% in 1989-1991. In 1994 they had reached a steady state (63% and 71%). In addition, a continued decrease in the use of calcium channel blockers was noted, from 36% in 1986-1958 to 17% in 1994. The increase in the prescription of beta-adrenergic blocking agents was especially remarkable in the subgroups for which a larger underuse was recorded in the previous study, such as the elderly. The proportion of patients prescribed an ACE inhibitor increased from 14% in 1989-1991 to 23% in 1994. In a multivariate analysis the prescription of ACE inhibitors was associated with female gender, hypertension during admission, heart failure during admission, and previous myocardial infarction. A substantial increase in the prescription of beta-adrenergic blocking agents and acetylsalicylic acid and a decrease in the prescription of calcium channel blockers was recorded between 1982 and 1994. The prescription rate of beta-adrenergic blocking agents has increased substantially in certain subgroups where underuse had been previously recorded. Most of the changes occurred in 1989-1991, and reached a steady state in 1994. In 1994 an increase in the prescription of ACE inhibitors was also recorded.