Prognosis of patients with positive exercise test and normal myocardial perfusion SPECT

Exercise SPECT myocardial perfusion imaging(Ex-MPI) is regarded as a predictive technique particularly in patients with coronary artery disease(CAD) capable of performing exercise testing. In clinical practice, we encounter equivocal situations of discordant findings between exercise ECG and MPI. We evaluated the prognosis of subjects with positive ECG and normal MPI findings, and predictive factors for cardiac events. 2571 Ex-MPI studies were reviewed over a period of 3 years. Subjects were followed for more than 2 years(24-56 months, mean 35±10months) for cardiac events after study. The cardiac events were defined as hard events(cardiac death and nonfatal myocardial infarction(MI)) and soft events(aggravation of CAD necessitating revascularization, congestive heart failure necessitating hospital admission). We evaluated age, sex, typical angina pain, rest ECG, hypertension, diabetes mellitus(DM), serum levels of cholesterol and LDL, smoking history, history of cerebrovascular disease(CVD) and peripheral artery disease(PAD), and rest left ventricular ejection fraction(LVEF) as clinical variables. Of 83 subjects with positive ECG and normal MPS findings, 6 were considered as false negative results confirmed with coronary angiography. There were 77 patients (mean age 52±10 years, 39 males) with positive ECG and normal MPI results. During the follow-up period, of 77 there were 3 cardiac events (annual rate 1.9%), no cardiac death, 2 nonfatal MIs (annual rate 1.3%) and 1 soft event (annual rate 0.6%). 2/39 males(5.1%), and 1/38 females(2.6%) had cardiac events. All cardiac events were observed within 2 years. 1-year cardiac event rate was 0.6% and 2-year cardiac event rate was 1.9%. Among clinical factors, male sex, typical chest pain and smoking history at the time of MPI were predictive of cardiac events. Patients with positive ECG and negative EX-MPI results have low risk for cardiac events. Nevertheless, the cardiac events cannot be excluded totally in some cases