Prognostic value of nitrate enhanced Tc99m MIBI SPECT study in detecting viable myocardium in patients with coronary artery disease

Background: Assessing the viability in akinetic myocardium is vital for predicting functional recovery after therapeutic management in patients with chronic coronary artery disease (CAD) and depressed left ventricular (LV) function. The present study aimed to evaluate the efficacy of Tc99m MIBI SPECT enhanced with nitroglycerine infusion in detecting myocardial viability, as well as to asses the relationship between the myocardial viability and the subsequent treatment and outcome of patients. Methods and results: Sixty-seven consecutive patients with CAD and LV dysfunction (LV ejection fraction 36.6 ± 8.4%) underwent Tc99m MIBI imaging – at rest and during intravenous nitroglycerine infusion – for viability assessment. Fourteen patients were treated pharmacologically (Group I), and fifty-three (Group II) were submitted to coronary revascularization (PTCR or CABG). Fifteen major cardiac events were observed during 25 months of the follow-up. A significantly worse event-free survival was registered in the subjects of Group I than in Group II subjects. The prognostic predictors of cardiac events were: (1) the number of viable, non-revascularized segments in perfusion imaging (p < 0.001), (2) the severity of the disease assessed by coronary angiography (p < 0.05). Conclusions: Viability detection in nitroglycerine infusion enhanced Tc99m MIBI imaging offers significant prognostic value in patients with CAD after myocardial infarction. Patients with preserved viability showed better prognosis after revascularization than those treated pharmacologically.