13N-ammonia myocardial blood flow and uptake: relation to functional outcome of asynergic regions after revascularization.

Abstract OBJECTIVES In this study we determined whether 13 N-ammonia uptake measured late after injection provides additional insight into myocardial viability beyond its value as a myocardial blood flow tracer. BACKGROUND Myocardial accumulation of 13 N-ammonia is dependent on both regional blood flow and metabolic trapping. METHODS Twenty-six patients with chronic coronary artery disease and left ventricular dysfunction underwent prerevascularization 13 N-ammonia and 18 F-deoxyglucose (FDG) positron emission tomography, and thallium single-photon emission computed tomography. Pre- and postrevascularization wall-motion abnormalities were assessed using gated cardiac magnetic resonance imaging or gated radionuclide angiography. RESULTS Wall motion improved in 61 of 107 (57%) initially asynergic regions and remained abnormal in 46 after revascularization. Mean absolute myocardial blood flow was significantly higher in regions that improved compared to regions that did not improve after revascularization (0.63 ± 0.27 vs. 0.52 ± 0.25 ml/min/g, p 13 N-ammonia uptake and FDG uptake was significantly higher in regions that improved (90 ± 20% and 94 ± 25%, respectively) compared to regions that did not improve after revascularization (67 ± 24% and 71 ± 25%, p 13 N-ammonia uptake was a significantly better predictor of functional improvement after revascularization (area under the receiver operating characteristic [ROC] curve = 0.79) when compared to absolute blood flow (area under the ROC curve = 0.63, p 13 N-ammonia uptake and FDG uptake (r = 0.68, p CONCLUSIONS These data suggest that beyond its value as a perfusion tracer, late 13 N-ammonia uptake provides useful information regarding functional recovery after revascularization. The parallel relationship among 13 N-ammonia, FDG, and thallium uptake supports the concept that uptake of 13 N-ammonia as measured from the late images may provide important insight regarding cell membrane integrity and myocardial viability.