Background: Contrast-enhanced cardiac magnetic resonance imaging (CMR) can determine the extent of myocardial scar from infarction (MI). However, the prognostic significance of unrecognized myocardial scar by CMR in patients without a history of MI is unknown.
Methods and results: One hundred ninety-five patients without a known prior MI underwent CMR for assessment of left ventricular (LV) function and late gadolinium enhancement (LGE). We assessed the prognostic value of LGE and other CMR variables beyond the strongest clinical predictors and built the best overall models for major adverse cardiac events (MACE) and cardiac mortality. During a median follow-up of 16 months, 31 patients (18%) experienced MACE, including 17 deaths. LGE demonstrated the strongest unadjusted associations with MACE and cardiac mortality (hazard ratios of 8.29 and 10.9, respectively; both P<0.0001). Patients in the lowest tertile of LGE-involved myocardium (mean LV mass, 1.4%) experienced a >7-fold increased risk for MACE. By multivariable analyses, LGE was independently associated with MACE beyond the clinical model (P<0.0001) or the clinical model combined with angiographically significant coronary stenosis (P=0.0007), LV ejection fraction (P=0.001), LV end-systolic volume index (P=0.0006), or segmental WMA (P=0.002). LGE remained the strongest predictor selected in the best overall models for MACE and cardiac mortality.
Conclusions: Among patients with a clinical suspicion of coronary artery disease but without a history of MI, LGE involving a small amount of myocardium carries a high cardiac risk. In addition, LGE provides incremental prognostic value to MACE and cardiac mortality beyond common clinical, angiographic, and functional predictors.