Detection of myocardial scar by contrast-enhanced cardiac magnetic resonance imaging in patients with troponin-positive chest pain and minimal angiographic coronary artery disease.

Patients who present with chest pain and elevated serum troponin levels may have minimal angiographic coronary artery disease, leading to diagnostic confusion. We investigated patients with troponin-positive acute coronary syndromes and minimal coronary artery disease (CAD) using contrast-enhanced cardiac magnetic resonance imaging to assess for myocardial scar. Twenty-three patients (54 +/- 8 years of age) who presented with chest pain, high troponin I level, and minimal angiographic CAD were included. Patients with a clinical pericarditis/myocarditis, tachyarrhythmia at presentation, previous myocardial infarction, or an alternative explanation for increased troponin I level were excluded. Myocardial scar was assessed with delayed-enhancement inversion-recovery imaging after administration of gadolinium. Hyperenhancement consistent with myocardial scar was seen in 7 of 23 patients (30%) and was located primarily in the right coronary artery distribution. Peak troponin level, clinical characteristics, and volumetric parameters were similar in patients with or without hyperenhancement. One patient had mid-myocardial enhancement that suggested undiagnosed myocarditis. There was a linear relation between the mass of myocardial scar and peak serum troponin level. In follow-up, subsequent cardiac events were more frequent in patients with hyperenhancement (43% vs 12.5%). In conclusion, patients with troponin-positive acute coronary syndromes may have significant myocardial scar even when minimal CAD is found on angiography.