Poststress left ventricular function in patients with coronary artery disease measured by Tl-201 ECG-gated SPECT

The phenomenon of reversible impairment in left ventricular function has been well described and is known as myocardial stunning.

To assess myocardial stunning in patients with stress-induced ischemia by the use of Tl-201 myocardial perfusion-gated single-photon emission computed tomography (SPECT).

Fifty-six patients (63+/-11 years old) with coronary artery disease participated in the study. All patients underwent exercise thallium scintigraphy. Electrocardiographically gated SPECT was obtained after stress (10 min after the injection of 111 MBq of thallium at the time of peak exercise) and at rest (after 180 min). The left ventricular ejection fraction (LVEF) and end systolic and end diastolic (EDV) volumes were determined using a quantitative gated SPECT (QGS) program. Patients were angiographically classified into three groups: one-vessel disease (n=38), two-vessel disease (n=9) and three-vessel disease (n=9). In 56 patients, resting left ventricular parameters determined by QGS were compared with those obtained by contrast left ventriculography (LVG) to investigate the feasibility of using thallium-gated SPECT to evaluate left ventricular function.

Good correlation was obtained between LVEF measured by QGS and LVEF measured by LVG (r=0.893, P<0.01). EDV measured by QGS correlated well with EDV measured by LVG (r=0.067, P<0.001). There was a significant difference between poststress LVEF and resting LVEF in patients with three-vessel disease (P<0.05); the difference was not significant in either of the other groups. The magnitude of the depression of LVEF after stress relative to that at rest correlated with the severity of ischemia (P<0.05).

Thallium-gated SPECT determines left ventricular function as well as perfusion does. Impaired poststress LVEF was detected using thallium-gated SPECT in patients with three-vessel disease. Poststress functional data would provide further diagnostic information in patients with coronary artery disease.