SPECT-Myocardial Perfusion Imaging as an Adjunct to Coronary Calcium Score for the Detection of Hemodynamically Significant Coronary Artery Stenosis

Abstract

Myocardial ischemia is a disorder that usually is caused by a critical coronary artery obstruction, which is also known as atherosclerotic coronary artery disease (CAD). CAD is the leading cause of death worldwide (Aggarwal et al., 2001 and Eggers et al., 2005). Diagnosing myocardial ischemia prior to a heart attack is important because ischemic heart disease is responsible for approximately 14% of all deaths worldwide, however approximately for one third of patients, CAD is not diagnosed until after a heart attack occurs. Fortunately, treating known CAD has tremendous benefits. Both coronary artery revascularization and medical therapies significantly reduce the morbidity and mortality rates of CAD. Since CAD is common and deadly, but treatable if detected early, early diagnosis of the condition is critical (Aggarwal et al., 2001 and Eggers et al., 2005). Therefore, it was hypothesized that combining the results of Myocardial perfusion imaging with the findings of Coronary Calcium scoring may enhance the prognostic value of both, resulting in a newer higher level of accuracy in patient screening and for the diagnosis and treatment of patients suspicious of having CAD (Gibbons et al., 2003 and Schenker et al., 2008). The aim of our study was to assess the value of combining SPECT MPI with CAS in increasing the diagnostic accuracy of both tests. Our study included 30 patients (mean age: 55.9±9.7 years; range: 39-72 years; 21 male patients; 9 female patients).The study was conducted at Kobry Alkobba Military hospital and ALFA Scan Radiology center, Cairo, Egypt during the period from June 2012 to December 2012. The study protocol was approved by Department of Cardiology at Ain Shams University. Patients were selected according to Framingham risk score as being moderate to high risk and the inclusion criteria were having 2 or more risk factors for CAD, being class II angina according to CCSC or any patient with inconclusive stress test. The exclusion criteria were ACS, history of (PCI,CABG), current pregnancy or age below 18 years old. All patients included into the study underwent stress-rest SPECT MPI using either treadmill exercise or pharmacological stressing using Dipyridamole; then all of the patients had their coronary calcium quantitatively calculated using a multidetector CT scanner and any patient with CS below 800Agatston score proceeded to MDCT angiography for evaluation of coronary anatomy using the same MDCT scanner. The study showed that combining results of SPECT MPI to CAC increased the sensitivity and specificity of both test in comparison to using each of them alone.