Correlation of myocardial perfusion single photon emission computed tomography with coronary artery calcium score in coronary artery disease- An Indian perspective

Full text: Objectives: The consequences of atherosclerosis can be detected by coronary artery calcium score (CACS) and stress induced myocardial ischemia on myocardial perfusion single photon emission computed tomography (MPS). We assessed the relationship between stress induced myocardial ischemia on (MPS) and magnitude of CACS by 64 slice computed tomography (CT) in patients undergoing both tests. Methods: Our study included 59 patients with no earlier history of coronary artery disease (CAD) of both sexes (males-47, females-12) in age group of 34-69 years. Our patients were referred by cardiologists after they underwent CACS. Of these 37 patients (63%) presented with symptoms which included chest pain (non-anginal, anginal, atypical) presence or absence of shortness of breath, and rest (37%) were asymptomatic. For each patient coronary risk factors were noted. All these patients underwent CACS and rest and stress MPS one-day protocol with Tc99m sestamibi within 7 days. According to CACS and symptoms, patients were divided into four groups, group A - asymptomatic <100 n=9, group B - symptomatic <100 n=26, group C- asymptomatic >100 n=13, group D - symptomatic >100 (n=11). The incidence of inducible ischemia in MPS was compared to the magnitude of CACS abnormality. Results: There were 21 patients (36%) with ischemic MPS. According to groups, group A - 11%(n=1), groupB- 38%(n=10), groupC- 30%(n=4) and group D- 54%(n=6) had ischemic MPS. From the above we observed that incidence of ischemic MPS is more with increasing CACS. And also it is noted that it is more frequent in patients who presented with symptoms irrespective of CACS who are at short-term risk. In negative MPS, CACS may be useful in long term risk stratification in finding out subclinical atherosclerosis. Conclusion: The general perception is that the CACS is a good tool for long-term risk stratification but it may be applicable to those patients with no significant risk factors. When there are risk factors MPS is a better indicator for risk stratification for CAD irrespective of CACS. Further studies incorporating prognostic follow- up are required. (author)