Impact of unrecognized myocardial scar detected by cardiac magnetic resonance imaging on event-free survival in patients presenting with signs or symptoms of coronary artery disease

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.