Long-term safety of an early ACE-inhibitor treatment of patients with acute myocardial infarction: results of the 3 year follow-up period on 696 Swiss patients randomized to the ISIS-4 trial. ISIS-Switzerland Study Group

Differential antiplatelet effects of angiotensin converting enzyme inhibitors: comparison of ex vivo platelet aggregation in cardiovascular patients with ramipril, captopril and enalapril

BACKGROUND

Increasing evidence suggests that angiotensin converting enzyme (ACE) inhibitors exert antithrombotic effects. Based on the assumption of differential effects of various ACE inhibitors on coagulation, the aim of the present study was to evaluate the coagulative activities of cardiovascular (CV) patients treated with either ramipril, captopril, and enalapril, and to compare these with patients treated with established antithrombotics such as aspirin (ASA) and clopidogrel or none of these medication.

METHODS

Blood samples of 320 CV patients with coronary artery disease and/or arterial hypertension were analyzed by wholeblood aggregometry. Platelet aggregation was determined by measuring the increase in impedance across paired electrodes in response to the aggregatory agents collagen and adenosine diphosphate (ADP), respectively. These data were correlated with medical treatment.

RESULTS

Platelet aggregation was attenuated ex vivo by ramipril and captopril as well as by ASA and clopidogrel. While collagen-induced platelet aggregation was significantly reduced by ramipril (35%; P <0.01) and captopril (27%; P = 0.01), no change was seen with enalapril. After induction with ADP, platelet aggregation was reduced in the presence of captopril therapy by 46% (P <0.05). There was a trend of inhibition with ramipril (32%, P = n.s.), whereas no antithrombotic effect was seen with enalapril.

CONCLUSION

Our findings demonstrate that ACE inhibitors decrease platelet aggregation ex vivo. The differential antiaggregatory profile may explain at least in part different effects of ACE inhibitors on cardiovascular endpoints as observed in large clinical trials.

Efficacy of perindopril in the treatment of systemic hypertension

The angiotensin-converting enzyme inhibitor, perindopril erbumine, has been approved for use in the United States only recently but has been studied extensively worldwide over the last decade. Placebo-controlled trials in a wide range of patients with hypertension, including the elderly, those with isolated systolic hypertension, and those with concomitant diseases such as hyperlipidemia, diabetes, cardiac arrhythmia, peripheral arterial occlusive disease, nephropathy with proteinuria, and chronic obstructive pulmonary disease, have shown that perindopril is highly effective in lowering both systolic and diastolic blood pressure (BP). Studies in which BP has been monitored for 24-hour intervals show that perindopril (1) has a gradual onset of action, (2) provides smooth BP control over its once-daily dosing interval, (3) has a trough-peak ratio of about 1, and (4) maintains its antihypertensive efficacy despite missed doses. Perindopril increases arterial compliance and reverses left ventricular hypertrophy in hypertensive patients. Both of these effects are at least partly independent of its ability to lower BP. Perindopril is safe and well tolerated in patients with hypertension. Rates of adverse events and discontinuation because of such events are low.