Evaluating the effect of the pretest probability on myocardial perfusion spect interpretetion in patients who has positive findings on MPS

Aim: In our study, we evaluated the role of pretest probability in patients, who had underwent MPS and dedected any perfusion defect. We studied to change the interpretetion of MPS as low or high probability positive with using probabilities.Methods:Between January 2008 and July 2011, 228 patients with positive MPS were included in our study. The patients were examined in two different groups like having prior coronary artery disease (KAHP) and no prior coronary artery disease (KAHN). Pretest probabilities of 139 KAHN patients was calculated from Diamond and Forrester method and classified into risk groups. We investigated not only patients' age, gender, chest pain but also their exercise data, summed differantial scores (SDS) and the coronary anjiography in both groups. Results: There is a significant difference in prevelance of coronary artery stenosis between KAHN (42.4%) and KAHP (74.2%) groups(p=0.000). It's also significantly different in risk groups that classified from probabilities. Sensitivity and spesifisity were %67.9 and %77.8 respectively when the posttest probability was %80. In patients with known coronary artery disease we couldn't find a relation between coronary stenosis, age, gender or SDS.Conclusion: We propose to calculate posttest probability in patients who refferred to MPS and if there is a perfusion defect on MPS, posttest probability is equal or higher than 80% reporting MPS as 'high probability positive'. If it's <80% we propose to evaluate the other risk factors or another diagnostic test before coronary angiography. KAHP patients should be reffered to coronary anjiography primarly if there is any reversible perfusion defect on MPS.