Discrepancy between stress electrocardiographic changes and nuclear myocardial perfusion defects in the prognostic assessment of patients with chest pain

Abstract

Objectives: The aim of the present study was to determine the long-term prognostic value provided by the exercise electrocardiographic (ECG) response to nuclear myocardial perfusion imaging (MPI) in the evaluation of patients with chest pain, focusing on patients with a discrepancy between the two tests.

Methods: A total of 1460 consecutive patients (777 female; 62.6 ± 11.4 years) undergoing exercise myocardial single-photon emission computed tomography (SPECT) were included. The endpoint was the occurrence of acute coronary syndrome, heart failure or cardiac death during follow-up.

Results: Ischemic ECG changes were observed during stress testing in 271 patients (18.5%) and 362 patients (24.7%) had positive (abnormal) exercise MPI results. There was a discrepancy between ECG and SPECT findings in 471 patients (32.2%). During the follow-up period (14.0-39.6 months), 224 patients (15.3%) presented cardiac events. The hazard ratios (HR) of ECG and MPI results to predict events were 1.506 (95% CI: 1.113-2.039) and 10.481 (95% CI: 7.799-14.080), respectively. In patients with negative MPI, the ECG response did not predict events (HR 1.214 [95% CI: 0.646-2.282]), the same as in patients with positive MPI (HR 1.203 [95% CI: 0.848-1.705]). Only in hypertensive patients with positive SPECT did the ECG show significant prognostic value (HR 1.937 [95% CI: 1.030-3.642]). In multivariate analysis, positive MPI proved an independent long-term prognostic factor (HR 10.536 [95% CI: 7.759-14.308]), but not ECG (HR 1.356 [95% CI: 0.994-1.850]).

Conclusion: MPI results (normal vs. abnormal) had strong predictive value and discrepant ECG results had no significant additive prognostic value.

Keywords: Electrocardiogram; Eletrocardiograma; Imagens de perfusão miocárdica; Myocardial perfusion imaging; Prognosis; Prognóstico; Prova de esforço; Stress test.