Early or deferred cardiovascular magnetic resonance after ST-segment-elevation myocardial infarction for effective risk stratification

Aims: In ST-segment-elevation myocardial infarction (STEMI), cardiovascular magnetic resonance (CMR) holds the potentiality to improve risk stratification in addition to Thrombolysis in Myocardial Infarction (TIMI) risk score. Nevertheless, the optimal timing for CMR after STEMI remains poorly defined. We aim at comparing the prognostic performance of three stratification strategies according to the timing of CMR after STEMI. Methods and results: The population of this prospective registry-based study included 492 reperfused STEMI patients. All patients underwent post-reperfusion (median: 4 days post-STEMI) and follow-up (median: 4.8 months post-STEMI) CMR. Left ventricular (LV) volumes, function, infarct size, and microvascular obstruction extent were quantified. Primary endpoint was a composite of all-death and heart failure (HF) hospitalization. Baseline-to-follow-up percentage increase of LV end-diastolic (EDV; ΔLV-EDV) ≥20% or end-systolic volumes (ESV; ΔLV-ESV) ≥15% were tested against outcome. Three multivariate models were developed including TIMI risk score plus early post-STEMI (early-CMR) or follow-up CMR (deferred-CMR) or both CMRs parameters along with adverse LV remodelling (paired-CMRs). During a median follow-up of 8.3 years, the primary endpoint occurred in 84 patients (47 deaths; 37 HF hospitalizations). Early-CMR, deferred-CMR, and paired-CMR demonstrated similar predictive value for the primary endpoint (C-statistic: 0.726, 0.728, and 0.738, respectively; P = 0.663). ΔLV-EDV ≥20% or ΔLV-ESV ≥15% were unadjusted outcome predictors (hazard ratio: 2.020 and 2.032, respectively; P = 0.002 for both) but lost their predictive value when corrected for other covariates in paired-CMR model. Conclusion: In STEMI patients, early-, deferred-, or paired-CMR were equivalent stratification strategies for outcome prediction. Adverse LV remodelling parameters were not independent prognosticators.