Comparison of the prognostic value of SPECT after nitrate administration and metabolic imaging by PET in patients with ischaemic left ventricular dysfunction

PURPOSE: We compared the prognostic value of 99mTc-tetrofosmin single-photon emission computed tomography (SPECT) after nitrate administration and positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) in patients with ischaemic left ventricular (LV) dysfunction. METHODS: Eighty-nine patients with previous myocardial infarction and LV dysfunction (LV ejection fraction 33 +/-10%) underwent 99mTc-tetrofosmin SPECT under control conditions (baseline) and after sublingual administration of 10 mg of isosorbide dinitrate (nitrate). Within 1 week, all patients underwent PET imaging with 18F-FDG. Four patients were excluded because of inadequate FDG uptake caused by severe diabetes. Follow-up data were obtained by phone contact with patients and by review of hospital or physicians' records. Cardiac death, myocardial infarction and late revascularisation for unstable angina were considered as events. Follow-up data were not available in three patients. Follow-up was 96% complete at a mean period of 29 +/- 19 months. RESULTS: At baseline SPECT, 59 (72%) patients had evidence of viable myocardium, while 23 did not. Of these latter patients, 12 (52%) demonstrated viable myocardium after nitrate and 13 (56%) had preserved metabolic activity. Cardiac events (cardiac death, myocardial infarction and late revascularisation for unstable angina) occurred in 24 (29%) patients. Event-free survival was similar in patients with and patients without viable myocardium at baseline SPECT (p = 0.8). In contrast, event-free survival was lower in patients with viable myocardium at nitrate SPECT and PET compared to those without viable myocardium (both p<0.05). CONCLUSION: In patients with ischaemic LV dysfunction, the prognostic value of SPECT imaging after nitrate is comparable to that of PET metabolic imaging.