Magnetic resonance vs technetium-99m pyrophosphate scintigraphy in the detection of perioperative myocardial necrosis.

BACKGROUND Perioperative myocardial infarction (POMI) is a complication of coronary artery bypass grafting (CABG) with a potential prognostic impact. Technetium-99m pyrophosphate myocardial scintigraphy (MS) is used in the diagnosis of POMI; however it shows a limited sensitivity for subendocardial lesions. Cardiovascular magnetic resonance imaging (CMRI), in turn, has a high accuracy in the detection of myocardial necrosis. OBJECTIVE To compare CMRI and MS for the detection of POMI after CABG. METHODS A total of 24 patients with chronic coronary artery disease were studied using the delayed contrast enhanced CMRI and MS before and after CABG by analyzing the development of areas of perioperative myocardial necrosis (POMI). Biochemical markers of myocardial injury (CKMB and troponin I) were also determined before and after surgery. RESULTS Nineteen patients completed the study. Of these, 6 (32%) presented POMI on CMRI and 4 (21%) on MS (p = NS). Of the 323 left ventricular segments assessed, 17 (5.3%) showed perioperative necrosis on CMRI and 7 (2.2%) on MS (p = 0.013). Moderate agreement was observed between the methods (kappa = 0.46). There was disagreement regarding the diagnosis of POMI in 4 (21%) cases, most of them with small areas of perioperative necrosis on CMRI which were not visualized on MS. In all cases with POMI on CMRI, significant CKMB and troponin I elevations were observed. CONCLUSION Moderate diagnostic agreement was observed between the methods for the detection of POMI, but CMRI enabled visualization of small areas of perioperative myocardial necrosis which were not identified on MS and were associated with elevation of biochemical markers of myocardial injury.