Prior Myocardial Infarction an Independent Predictor of Adverse Cardiovascular Events

Background: The prognostic benefit of secondary prevention in those with prior myocardial infarction (MI) is well documented. However, long-term compliance with secondary prevention medications is variable in this group. We examined clinical outcomes and use of secondary prevention medications amongst patients with a prior MI re-presenting with an acute MI. Methods: We prospectively enrolled patients with acute MI between 2012 and 2015. Demographics, clinical characteristics, medications and one-year outcomes were collected. Major adverse cardiovascular events (MACE) were defined as a composite of all-cause mortality, non-fatal MI, ischaemic stroke, heart failure and unplanned revascularisation at 1 year. Results: Of 1160 patients, 266 (23%) had a history of prior MI. These patients were older, more likely to be male, and had higher incidence of hypertension, dyslipidaemia and diabetes (all p < 0.05) than those presenting with a first MI. MACE was significantly higher in prior MI patients than patients presenting with a first MI (21% versus 10%, p < 0.0001). After correcting for confounding factors, prior MI remained an independent predictor of MACE (OR1.6, 95%CI 1.06-2.46, p < 0.05). At admission only 59% of prior MI patients were on a beta blocker, 68% on a statin and 80% on aspirin. This increased to 86% beta blocker, 89% statin and 98% aspirin use in this group at the time of discharge (all p < 0.0001). Conclusion: Patients with prior MI representing with acute MI have substantially worse clinical outcomes. The use of secondary prevention medications at point of admission appears to be sub-optimal and improved significantly at the time of discharge.