Long-term prognostic value of microvascular obstruction by cardiac magnetic resonance in ST-segment elevation myocardial infarction

TL;DR

This study shows that microvascular obstruction detected by MRI after heart attacks is linked to higher death risk for up to six years, but not beyond.

Contribution

The study provides long-term (up to 6 years) prognostic data on microvascular obstruction in STEMI patients using cardiac MRI.

Findings

MVO was associated with a 2.23-fold higher risk of all-cause mortality up to six years post-STEMI.

The association between MVO and mortality dissipated after six years of follow-up.

MVO was not significantly linked to combined mortality and ischemic events before or after six years.

Abstract

Microvascular obstruction (MVO) portends a higher risk of remodelling and adverse events following ST-segment elevation myocardial infarction (STEMI). However, data regarding the implications of MVO in STEMI beyond five years of follow-up are scarce.

This is a pooled analysis of three observational studies including 876 prospectively enrolled reperfused first STEMI patients, who underwent cardiac magnetic resonance imaging with late gadolinium enhancement (LGE), between 2003–2019. Median follow-up duration was 6.3 (IQR 3.6–9.3) years. The primary outcome was all-cause mortality. The secondary outcome was a combined endpoint of all-cause mortality and recurrent ischemic events (i.e., myocardial infarction or stroke). We performed Cox regression analyses with a time-dependent covariate.

The study population consisted of 876 patients, mean age 59 years ± 12, 720 men (82%). MVO was present in 499 patients (58%). The presence of MVO was independently associated with all-cause mortality up to six years post-STEMI (Hazard Ratio [HR] 2.23, 95% CI 1.09–4.57, p = 0.029), but not after six years post-STEMI (HR 0.98, 95% CI 0.45–2.12, p = 0.958). Presence of MVO was not significantly associated with a combined endpoint of all-cause mortality and recurrent ischemic events before or after six years of follow-up (HR 1.27, 95% CI 0.81–1.99, p = 0.294 and HR 0.68, 95% CI 0.35–1.31, p = 0.244, respectively).

In STEMI patients, the presence of MVO by cardiac magnetic resonance imaging is associated with a more than two-fold higher risk of all-cause mortality up to six years after the index event. This relation seems to dissipate beyond this time period.

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