Objectives: We assessed whether a combination of summed stress scores (SSS) using exercise myocardial perfusion SPECT (Ex-SPECT) and maximal heart rate accurately predicts cardiac events through a sub-analysis of J-ACCESS (Japanese Assessment of Cardiac Events and Survival Study by Quantitative Gated SPECT) which was conducted to evaluate the prognosis of Japanese patients with suspected ischemic heart disease.
Methods: In J-ACCESS, 2,373 patients with suspected coronary artery disease not receiving beta-blocker treatment underwent Ex-SPECT. These patients were categorized into the following four groups: Group A [achieved target heart rate (THR) and SSS < 4: n = 631], B (did not achieve THR and SSS < 4: n = 612), C (achieved THR and SSS >or= 4: n = 570), and D (did not achieve THR and SSS >or= 4: n = 560). We evaluated the incidence rate of cardiac events including cardiac death, myocardial infarction, and heart failure requiring hospital admission during a 3-year period.
Results: In Group A, B, C, and D, 9 of 631 (1.4%), 15 of 612 (2.4%), 23 of 570 (4.0%) and 30 of 560 (5.4%) patients experienced cardiac events, respectively. Although the hazard ratio of the SSS >or= 4 was 2.45 (p < 0.001) and that of the attained THR was 0.69 (p = 0.10) in the multiple Cox regression analysis, Kaplan-Meier curves showed that the cardiac events rate was lower in the order of A, B, C, and D (p < 0.001).
Conclusion: The combination of SSS using Ex-SPECT and the maximal heart rate is a useful predictor of cardiac events in patients with suspected coronary artery disease.