Risk of Myocardial Infarction With Combination Antihypertensive Regimens Including a Dihydropyridine Calcium Channel Blocker in Hypertensive Diabetics

OBJECTIVES: The primary objective of this study was to determine if there was an increased risk of myocardial infarction (MI) in a high-risk hypertensive diabetic managed care population receiving combination antihypertensive therapy including a dihydropyridine (DHP) calcium channel blocker (CCB). METHODS: A retrospective, population-based, case-control study design was used to determine the risk of MI versus the prescribed antihypertensive drug regimen. During 1997-1999, 6,096 diabetics with hypertension were identified. After exclusions, there were 131 high-risk study patients who suffered an MI during the study period. These were compared to an equally matched sample. High-risk patients were defined as those with a medical history of previous MI, angina pectoris or ischemic heart disease, or those who had undergone a coronary artery bypass graft and/or angioplasty procedure. Patients were then assigned to Group I cases and controls (DHP use) and Group II cases and controls (no DHP use). Odds ratios (OR) and 95% confidence intervals (CI) were determined for the independent variables and antihypertensive drug regimens. Logistical regression analysis was used to model age, ethnicity, and potential risk factors to identify any differences among calcium channel blockers. RESULTS: After adjusting for age and gender, the OR for an MI in patients on a combination DHP regimen was 0.75 (95% CI, 0.44, 1.29). The OR for other regimens ranged from 0.52 to 1.16, with no significant difference between antihypertensive drug classes. In comparison to non-dihydropyridines (NDHPs), the OR for DHPs was 1.38 (95% CI, 0.54, 3.54), but it was determined to not be statistically different (P=0.5065). CONCLUSIONS: No increase in risk of MI could be determined with the use of a combination antihypertensive regimen including a DHP CCB when compared to other antihypertensive drugs in a matched high-risk population of patients with hypertension and diabetes. Choice of antihypertensive drug regimen may be less important than strategies that focus on achieving optimal disease outcomes to reduce the incidence of MI and hospitalization and lower health care costs in this high-risk population in managed care.