Prognostic value of rest myocardial perfusion imaging in patients with chest pain and negative troponin I

Abstract

Background: Rest myocardial perfusion imaging (RMPI) in the evaluation of patients with chest pain has been shown to provide diagnostic information, but may also provide prognostic data. The aim of this study was to find the relationship between RMPI results and the occurrence of cardiac ischemic events (death, myocardial infarction or myocardial revascularization) over a ninety-day period in patients with chest pain and with negative troponin I. Methods: Patients (pts) without a prior myocardial infarction, admitted for chest pain in the emergency department, were studied by RMPI. Troponin I was assessed before RMPI and four hours later. Patients with values of troponin considered positive for myocardial injury (> 0,20ng/ml) were excluded. Tomographic perfusion images were acquired after the injection of 15mCi of 99mTc-tetrofosmin and analyzed using a 17 segment scoring system.The summed rest score was expressed as a percentage of the maximal possible score (% summed rest perfusion score SRPS). Regarding the result of the exam, 2 groups were established: I - %SRPS ≤ 15%; II > 15%. Ischemic events were: death, myocardial infarction and myocardial revascularization over a 90-day period. Statistical analysis was performed using Kaplan-Meier survival curves and the Logrank test. Results: Fifty-nine pts were enrolled, 41 pts were included in group I (69,5%), 18 in group II (30,5%).The cardiac events were: 8 revascularizations and 1 death (17,6%). Two pts from group I (4,9%) and 7 pts from group II (38,9%) had a cardiac event. Using the Logrank test with a Mantel-Cox analysis a p = 0,0007 was found. Conclusion: In this study a relationship was found between the occurrence of cardiac events and the extent of rest perfusion defects. RMPI in patients with chest pain and negative troponin I could be used for risk stratification regarding the underlying ischemic heart disease. Logrank p = 0,