Impact of Multiple Myocardial Scars Detected by CMR in Patients Following STEMI

OBJECTIVES: This study investigated the incidence and long-term prognostic importance of multiple myocardial scars in cardiac magnetic resonance (CMR) in a large contemporary cohort of patients with ST-segment elevation myocardial infarction (STEMI).

BACKGROUND: Patients presenting with STEMI may have multiple infarctions/scars caused by multiple culprit lesions, previous myocardial infarction (MI) or procedure-related MI due to nonculprit interventions. However, the incidence, long-term prognosis, and distribution of causes of multiple myocardial scars remain unknown.

METHODS: CMR was performed in 704 patients with STEMI 1 day after primary percutaneous coronary intervention (PCI) and again 3 months later. Myocardial scars were assessed by late gadolinium enhancement (LGE). T2-weighted technique was used to differentiate acute from chronic infarctions. The presence of multiple scars was defined as scars located in different coronary territories. The combined endpoints of all-cause mortality and hospitalization for heart failure were assessed at 39 months (interquartile range [IQR]: 31 to 48 months).

RESULTS: At 3 months, 59 patients (8.4%) had multiple scars. Of these, multiple culprits in STEMI were detected in 7 patients (1%), and development of a second nonculprit scar at follow-up occurred in 10 patients (1.4%). The most frequent cause of multiple scars was a chronic scar in the nonculprit myocardium. The presence of multiple scars was independently associated with an increased risk of all-cause mortality and hospitalization for heart failure (hazard ratio: 2.7; 95% confidence interval: 1.1 to 6.8; p = 0.037).

CONCLUSIONS: Multiple scars were present in 8.4% of patients with STEMI and were independently associated with an increased risk of long-term morbidity and mortality. The presence of multiple myocardial scars on CMR may serve as a useful tool in risk stratification of patients following STEMI. (DANish Study of Optimal Acute Treatment of Patients With ST-elevation Myocardial Infarction [DANAMI-3]; NCT01435408) (Primary PCI in Patients With ST-elevation Myocardial Infarction and Multivessel Disease: Treatment of Culprit Lesion Only or Complete Revascularization [PRIMULTI]; NCT01960933).