Myocardial perfusion defect assessed by single-photon emission computed tomography and frontal QRS-T angle in patients with prior anterior myocardial infarction.

The frontal QRS-T angle is one of the markers of ventricular repolarization. We sought to assess the effects of myocardial perfusion defect on QRS-T angle in patients with prior anterior myocardial infarction (MI). Seventy-one patients with prior anterior MI and 71 age- and sex-matched control subjects having no myocardial perfusion defect were selected. Frontal QRS-T angle was defined as the absolute value of the difference between the frontal plane QRS axis and T-wave axis. The extent of myocardial perfusion defect was determined using myocardial perfusion single-photon emission computed tomography (SPECT). The extent of myocardial perfusion defect of patients with prior anterior MI was 21.8 ± 13.7%. Frontal QRS-T angle was significantly larger in patients with prior anterior MI than control subjects (82° ± 49° vs 30° ± 26°, p < 0.001). Prevalence of abnormal frontal QRS-T angle defined as more than 90° was significantly higher in patients with prior anterior MI than control subjects (42% vs 4%, p < 0.001). Multivariate linear regression analysis showed that age (β=0.18, p = 0.02) and myocardial perfusion defect (β = 0.46, p = 0.02) were independent determinants of frontal QRS-T angle. Our results suggest that the extent of myocardial perfusion defect is an independent determinant of frontal QRS-T angle in patients with prior anterior MI.