'False-positive' myocardial perfusion imaging: correlation with cardiovascular risk factors and effect on event-free survival

Background In the absence of significant coronary stenoses, stress-induced myocardial perfusion abnormalities at gated single photon emission computed tomography (g-SPECT) are usually considered to be a 'false-positive' result. Our goal was to investigate how false-positive g-SPECT perfusion abnormalities relate to cardiovascular risk factors and whether they provide any prognostic information. Methods From 1999 to 2005, a group of 130 anginal patients with myocardial perfusion abnormalities at stress g-SPECT, with normal coronary angiography or less than 50% lumen reduction and with a left ventricular ejection fraction more than 0.45, was selected. The extent of myocardial perfusion abnormalities after stress was quantified using the summed difference score (SIDS). Results Using a logistic regression model, it was found that cardiovascular risk factors (diabetes mellitus, arterial hypertension, smoking habit, hypercholesterolemia and obesity) were closely related (r= 0.96) to the SDS. During a 44 +/- 7-month follow-up, six patients experienced nonfatal cardiac events. An SDS more than 7 (P < 0.0001) and diabetes mellitus (P < 0.0001) were the only independent predictors of event-free survival using Cox proportional hazard regression analysis. Conclusion In patients with anginal-like chest pain and without significant coronary stenoses, stress-induced myocardial perfusion abnormalities at g-SPECT correlate with cardiovascular risk factors and are independent predictors of the few, minor adverse cardiac events during the follow-up.