Clinical significance of ischemic electrocardiographic changes during stress myocardial perfusion imaging: sub-analysis of the J-ACCESS study.

Objectives: The cardiac event rate among the countries varies according to ethnicity. Some reports have identified that ischemic heart disease often occurs at a low incidence and is often milder in Japan compared to other countries. Therefore, the present study was designed to determine the clinical significance and prediction for cardiac events in patients who showed ischemic ECG changes during stress myocardial perfusion SPECT.

Methods: Among 4,670 registered patients for Japanese-assessment of cardiac event and survival (J-ACCESS) study, patients with conduction abnormality on baseline were excluded and revascularization within 60 days of SPECT study were censored from the prognostic portion of analysis. Stress and rest myocardial perfusion SPECT imaging with (99m)Tc-tetrofosmin were performed and occurrence and nature of cardiac events were investigated at 1, 2 and 3 years after registration. Both PCI and CABG, as well as recurrent angina and non-severe heart failure were classified as soft events. Cardiac death, non-fatal MI and heart failure requiring hospitalization were classified as major cardiac events, and hard events comprised cardiac death and non-fatal MI.

Results: A total of 3,125 patients performed exercise (n = 2,383) or vasodilator (n = 742) stress MPI and significant ischemic ECG changes were obtained in 538 during exercise and 35 during vasodilator stress. Kaplan-Meier analysis revealed that the patients with both ischemic ECG changes and reversible perfusion defect on MPI had significantly higher incidence for major cardiac events, such as cardiac death, non-fatal MI and severe heart failure (P = 0.0038), and for cardiac hard events, such as cardiac death and non-fatal MI (P = 0.0028), in exercise stress. Interestingly, patients without reversible perfusion defect showed significantly fewer events despite presence of ischemic ECG changes.

Conclusions: Ischemic ECG changes during exercise stress are well associated with higher incidence of cardiac events in patients demonstrated reversible perfusion defect on MPI.