To Örebro University

BACKGROUND: Around 5-10% of all myocardial infarction patients have non-obstructive coronary arteries. Studies investigating the importance of follow-up and achievement of conventional secondary prevention targets in these patients are lacking.

METHODS: In this analysis from the SWEDEHEART registry, we investigated 5830 myocardial infarction patients with non-obstructive coronary arteries (group 1) and 54,637 myocardial infarction patients with significant coronary artery disease (≥50% stenosis; group 2). Multivariable- and propensity score-adjusted statistics were used to assess the reduction in the one-year risk of major adverse events associated with prespecified secondary preventive measures: participation in follow-up at 6-10 weeks after the hospitalization; achievement of secondary prevention targets (blood pressure and low-density lipoprotein cholesterol levels in the target ranges, non-smoking, participation in exercise training).

RESULTS: Patients in group 1 were less often followed up compared to patients in group 2 and less often achieved any of the secondary prevention targets. Participation in the 6-10 week follow-up was associated with a 3-20% risk reduction in group 1, similar as for group 2 according to interaction analysis. The improvement in outcome in group 1 was mainly mediated by achieving target range low-density lipoprotein cholesterol levels (24-32% risk reduction) and, to a smaller extent, by participation in exercise training (10-23% risk reduction).

CONCLUSIONS: Selected secondary preventive measures are associated with prognostic benefit in myocardial infarction patients with non-obstructive coronary arteries, in particular achieving target range low-density lipoprotein cholesterol levels. Our results indicate that these patients should receive similar follow-up as myocardial infarction patients with significant coronary stenoses.