Prognostic Value of SPECT Myocardial Perfusion Tomography on Cardiac Events
|Keywords||Coronary artery disease Myocardial perfusion imaging Cardiac events|
Background PECT Myocardial perfusion imaging（MPI）is accurate for the diagnosis of coronary artery disease(CAD), and the people have gradually recognized its importance of the prognostic value. Objectives To probe into the prognostic value of MPI for patients with CAD, evaluate the impact of imaging’s pattern, the type of the perfusion’s result and the heart rate in the stress myocardial perfusion on cardiac events, explore the risk factors of cardiac event occurrence, provide risk stratification and important evidence for clinical therapeutic strategy. Materials and Methods Of the 1371 cases, 1047 cases（76.37%）successfully followed up. The mean interval of following up was 33.25±14.95（1~56）months, and even longer than 18 months for patients with no cardiac events. Among them, 746 males,301 females, average 55.94±12.46(16~90) years, 330 pts with Hypertension, 324 pts with Hyperlipemia, 172 pts with Diabetes and 294 pts with the family history of CAD. All patients underwent SPECT MPI. Death due to primary cardiac cause, or nonfatal acute myocardial infarction and revascularization were considered cardiac events. Results MPI result were categorized as normal or abnormal (fixed or reversible defects and 1 segment defect, 2 segment defects and ≥3 segment defects). During the follow up period, MPI was normal in 480 pts, abnormal in 567 cases. Overall， 20.81% of the patients with abnormal SPECT imaging occurred cardiac events, but only 2.08% of the patients with normal imaging did (Log-rank, chi-square 126.36, P <0.001). By Cox proportional regression analysis, the range of defects, diabetes and family history of CAD were independent predictor for cardiac events occurrence, especially the range of <WP=7>defects. Of 1047 patients, 172 (16.43%) were diabetic. Patients with diabetes had 42 cardiac events (24.42%), compared with 86 cardiac events (9.83%) in the nondiabetic cohort (Log-rank, chi-square 28.75, P <0.001). The sensitivity of MPI in detecting CAD was 94.4% and specificity was 80% compared with CAG. The radionuclide cardiography is a noninvasive and very helpful for diagnosis of CAD. In 206 patients who underwent stress-rest myocardial perfusion imaging, there are 2 cardiac events in 133 normal MPI group, 13 in 20 reversible defects’ group(ischemic group) and 4 in 51 fixed defects’ group(infarction group). The rate of cardiac events occurrence is 1.5%, 65% and 7.8% respectively. There was significance difference between ischemic patient and infarction patient or normal MPI patient group (P <0.001), but no difference between infarction patient and normal MPI patient group(P> 0.01250). The prognostic value of ischemic patient group was the best one. Patients with abnormal result of the stress MPI had a significantly higher cardiac events than those with abnormal rest ones (chi-square 5.80，P =0.016), and the prognoses of patients with normal stress MPI result were better than those with normal rest ones (chi-square 8.94，P =0.0028). According to the exercise heart rate reached submaxmumdose or not, the patients were devided into normal group and abnormal group (heart rate didn’t reach submaxmumdose). The positive MPI result and the rate of cardiac events in abnormal group were higher than normal group. Conclusions：SPECT myocardial perfusion imaging (MPI) is valuable in early detecting latent myocardial ischemia, and effectively evaluate the prognoses. Compared with rest MPI, the stress one is a better method to analyze the patient’s condition. The presence and the extent of abnormal MPI predicted subsequent cardiac events. Using MPI in conjunction with clinical information can provide risk stratification of patients and evidence for clinical therapeutic strategy.