99Tcm-sestamibi tomoscintigraphy at rest and after nitrate administration in predicting wall motion recovery after...

To evaluate whether nitroglycerin administered before the injection of sestamibi improves the detection of viable but hypoperfused myocardium, 41 post-infarction patients with left ventricular dysfunction underwent echocardiography and SPET at rest and after nitrate administration. In 25 revascularized patients, perfusion at rest and contractility were assessed 3-4 months after coronary artery bypass grafting. Perfusion (PI) and wall motion indices (WMI) were calculated for each revascularized area. There was a strong correlation between contractility and perfusion defect (r = 0.58, P < 0.0001). Nitrates significantly reduced the number of perfusion defects in hypokinetic (delta PI = 0.25 +/- 0.66) and akinetic (delta PI = 0.32 +/- 0.62), but not in dyskinetic (delta PI = 0.08 +/- 0.62), segments. Twenty-five revascularized patients had 110 asynergic segments and 136 segments with a resting perfusion defect. Function improved in 42% and perfusion in 64% of segments after surgery. Viable segments had a lower PI at rest (2.78 +/- 1.38 vs 3.86 +/- 1.29, P < 0.001) and a lower WMI (2.46 +/- 0.50 vs 2.79 +/- 0.59, P = 0.002). Nitrates reduced the number of perfusion defects slightly more in viable than non-viable segments (delta PI = 0.58 +/- 0.89 vs 0.30 +/- 0.46, P = 0.06). Contractility and perfusion at rest were the most important predictors of functional recovery. The sensitivity and specificity in predicting contractile improvement were 74% and 64% for resting SPET respectively, and 80% and 50% for nitrate SPET respectively. Nitrate administration significantly reduces perfusion defects in asynergic regions; however, its usefulness in predicting contractile recovery may be limited owing to its low specificity. Contractility and sestamibi uptake at rest were the strongest predictors of post-operative wall motion improvement.