As part of the Italian Genetic Study on Early-onset Myocardial Infarction, data from 1,778 men and 222 women aged less than 45 years who presented with an MI at one of 125 Italian coronary care units (1998–2002) were analysed. During a median follow-up of 20 years, the primary endpoint of recurrent non-fatal MI, stroke or cardiovascular death occurred in 25.7% of women compared with 37.0% of men (hazard ratio [HR] 0.69; 95% confidence interval [CI] 0.52–0.91; p=0.01). When the components of the primary endpoint were analysed separately, recurrent MI was less frequent in women vs. men (14.2% vs. 25.4%; HR 0.53; 95% CI 0.37–0.77; p<0.001). However, women were more likely to have a stroke compared with men (7.7% vs. 3.7%; HR 2.02; 95% CI 1.17–3.49; p=0.012). Women were more than twice as likely to have normal or nonsignificant coronary artery stenoses at the time of angiography than men (36.5% vs. 15.4%; p<0.001), but coronary artery dissection was more frequent in women (5.4% vs. 0.7%; p<0.01).
More men than women had cardiovascular risk factors, including smoking (46.5% vs. 42.8%), alcohol consumption (65.3% vs. 27.4%), dyslipidaemia (62.3% vs. 50.7%) and diabetes (7.8% vs. 5.4%) (all p<0.001). Although statin prescription at discharge was similar in men and women, men were more likely to be prescribed beta-blockers, aspirin and angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. The disparity in prescribing may be due to the lower burden of coronary artery disease found in women in the study. It could also relate to the general under-prescribing of medication for women compared with men as seen in other studies of acute cardiac events.
Prof. Ardissino concluded, “In contrast to the prevailing literature for MI in general, premenopausal women experiencing early-onset MI have favourable long-term outcomes compared with men, despite being prescribed fewer preventive medications.” Distinct mechanisms of cardiovascular disease and the protective effect of oestrogen may be responsible for these differences.