Serial assessment of left ventricular performance at rest and during bicycle exercise by ECG-gated myocardial perfusion SPECT

Clinical Applications of ECG-gated Myocardial Perfusion SPECT

Erectrocardiogram (ECG)-gated myocardial perfusion single photon emission computed tomography (SPECT) can be used to assess myocardial perfusion and left ventricular function simultaneously. Various clinical applications of gated SPECT and their usefulness have been reported. The functional variables that can be determined with gated SPECT have been limited to systolic indices. Therefore, we evaluated left ventricular diastolic function with gated SPECT using data obtained from various frames per cardiac cycle and found that date generated from 32-frames are suitable for clinical use. Serial assessment of left ventricular function was also performed during bicycle exercise and dobutamine stress by means of gated SPECT using short-time data collection. These techniques, therefore, have the potential to provide useful information for evaluating myocardial conditions, such as hibernation and residual ischemia in infarct areas. Recently, we have developed a new technique for three-dimensional registration of CT coronary angiography (CTCA) and ECG-gated myocardial perfusion SPECT. This technique of registration may assist the integration of information from gated SPECT and CTCA and may have clinical application for the diagnosis of ischemic heart disease. These various applications would contribute to the development of nuclear cardiology.

Left ventricular systolic/diastolic function evaluated by quantitative ECG-gated SPECT: comparison with echocardiography and plasma BNP analysis

OBJECTIVE

The aim of this study was to evaluate the left ventricular (LV) functional parameters calculated using quantitative electrocardiography (ECG)-gated myocardial perfusion single photon emission computed tomography (QGS). In addition to LV systolic parameters, diastolic parameters were compared with those by ultrasound echocardiography (UCG) and also with plasma B-type natriuretic peptide (BNP) concentrations.

METHODS

We examined 46 patients with various forms of heart disease. By the QGS data with 16 framing data acquisition using technetium (Tc)-99m methoxyisobutylisonitrile (MIBI) perfusion, we calculated the following parameters: LV end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF), peak filling rate (PFR), filling rate during the first third of the filling time (1/3FR) and first third filling fraction (1/3FF). By UCG, we measured mitral early to atrial (E/A) wave velocity ratio and pulmonary venous inflow systolic/diastolic (S/D) ratio as diastolic functional parameters. Plasma BNP concentrations were also measured.

RESULTS

There was a significant correlation between LVEDV, ESV and EF measured by QGS and UCG (EDV, r = 0.71, p < 0.001; ESV, r = 0.82, p < 0.001; EF, r = 0.75, p < 0.001). The PFR, 1/3FR and 1/3FF obtained by QGS correlated positively with E/A ratio (PFR, r = 0.54, p < 0.001; 1/3FR, r = 0.61, p < 0.001; 1/3FF, r = 0.42, p < 0.01) and negatively with S/D ratio (PFR, r = -0.40, p < 0.01; 1/3FR, r = -0.38, p < 0.05; 1/3FF, r = -0.39, p < 0.01) obtained by UCG. Plasma BNP concentrations in EF < 50% patients were greater than those in EF > or = 50% patients (335.2 +/- 60.2 vs. 101.2 +/- 41.3 pg/ml, p < 0.01, both n = 17). Plasma BNP levels were also compared between higher and lower 1/3FF patients matched for LVEF. Plasma BNP concentrations in 1/3FF < 35% patients were significantly greater than those in 1/3FF > or = 35% patients (312.9 +/- 62.5 vs. 120.5 +/- 32.8 pg/ml, p < 0.05, both n = 14).

CONCLUSIONS

The degree of LV systolic and diastolic dysfunctions evaluated by QGS correlated with that by UCG or BNP. The QGS functional parameters offer useful information regarding cardiac failure.

Prognostic value of ECG-gated thallium-201 single-photon emission tomography in patients with coronary artery disease

BACKGROUND

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

OBJECTIVE

Thallium-201 myocardial perfusion gated SPECT was used to evaluate myocardial stunning and its incremental prognostic value in patients with coronary artery disease.

PATIENTS AND METHODS

Fifty-six patients (aged 63+/-11 years) with coronary artery disease were included in this study. All subjects underwent exercise thallium scintigraphy. ECG-gated SPECT was obtained both at post-stress (10 minutes after the injection of 111 MBq of thallium at the time of peak exercise) and at rest (180 minutes). The left ventricular ejection fraction (LVEF) and end-systolic and end-diastolic volume (ESV, EDV) were determined by a quantitative gated SPECT (QGS) program.

RESULTS

Follow-up was complete in all patients (mean 569 days). The magnitude of the depression of post-stress LVEF relative to the rest LVEF was correlated with the severity of ischemia (p < 0.05). The group with a median LVEF of more than 45% had a significantly higher event-free rate (p < 0.01).

CONCLUSION

Assessment of post-stress left ventricular function by gated-SPECT provides incremental prognostic information and is useful in predicting cardiac events in patients with suspected or definite coronary artery disease.