Exercise and rest technetium-99m-tetrofosmin lung uptake: correlation with left ventricular ejection fraction in patients with coronary artery disease

Incremental prognostic value of 99mTc-tetrofosmin early poststress pulmonary uptake. Determination of the optimal cut-off value

OBJECTIVES

To evaluate the incremental prognostic value of (99m)Tc-tetrofosmin early poststress lung/heart ratio (eLHR) and to assess the optimal cut-off value.

MATERIALS AND METHODS

We studied 503 patients (aged 61.3 years/SD = 8.6 years, 302 men) with stress/rest (99m)Tc-tetrofosmin myocardial gated-single photon emission computed tomography and coronary angiography. To evaluate myocardial ischemia, the summed stress score, summed rest score, and summed difference score indices were calculated. For the eLHR calculation, an anterior image was acquired 4-6 min after radiotracer injection at stress; eLHR was defined as the mean counts/pixel in the lung region of interest divided by the mean counts/pixel in the myocardial region of interest. The incremental prognostic value of eLHR was evaluated by a significant increase in the global χ(2) of the Cox proportional hazard model that included clinical, exercise, angiographic, and scintigraphic variables. Using the receiver operating characteristic analysis, the optimal cut-off of eLHR for the prediction of cardiac events was determined.

RESULTS

During the follow-up period, hard cardiac events occurred in 50 (9.9%) and soft cardiac events in 61 (12.1%) patients. Receiver operating characteristic curve analysis showed that the optimal cut-off of eLHR for the prediction of cardiac events was 0.51, with a sensitivity of 78.4% and specificity of 72.2%. The area under the curve was 0.82 (95% confidence interval: 0.77-0.87). Multiple Cox regression analysis revealed that eLHR more than 0.51 (hazard ratio = 7.78; 95% confidence interval: 5.00-12.11) provided incremental prognostic value over clinical exercise testing and scintigraphic data for cardiac events.

CONCLUSION

A (99m)Tc-tetrofosmin eLHR value larger than 0.51 added incremental value to other variables for the prediction of cardiac events.

Decreased myocardial perfusion SPECT lung-to-heart ratio: Lucent lungs

We present a case of a patient with chronic obstructive pulmonary disease whose myocardial perfusion SPECT imaging demonstrated diffusely decreased Tc-99m sestamibi lung uptake ("lucent lungs"); our results indicate that there may be a lower limit of normal for lung-to-heart ratio, below which pathology can be inferred.

Long-term prognostic value of early poststress (99m)Tc-tetrofosmin lung uptake during exercise (SPECT) myocardial perfusion imaging

PURPOSE

The aim of this study was to determine the long-term prognostic value of early poststress lung/heart ratio (LHR) of (99m)Tc-tetrofosmin radioactivity.

METHODS

We studied 276 patients (aged 62.2 + or - 8.9 years, 168 men) with stress/rest (99m)Tc-tetrofosmin myocardial gated-SPECT and coronary angiography. To evaluate myocardial ischaemia, we calculated the summed stress score, summed rest score and summed difference score indices. For the eLHR calculation, an anterior image was acquired, 4-6 min after radiotracer injection at stress (eLHR was defined as mean counts per pixel in the lung region of interest divided by the mean counts per pixel in the myocardial region of interest). Cardiovascular death and nonfatal myocardial infarction were considered as hard cardiac events, and late revascularization procedures as soft cardiac events. The Cox proportional hazards model in a stepwise method was used to determine the independent predictors for hard and soft cardiac events.

RESULTS

During the follow-up period hard cardiac events occurred in 28 patients (10.1%) and soft cardiac events in 32 patients (11.6%). Implying multiple Cox regression analysis, eLHR was found to be a significant independent predictor for both soft and hard cardiac events. The hazard ratio (for a 0.1 unit increase) was 4.41 (95% CI 1.52-12.73, p=0.006) for soft cardiac events and 4.22 (95% CI 2.07-8.62, p<0.001) for hard cardiac events. The other significant prognostic factors were use of beta-blockers, the summed stress score and the use of nitrates for soft events, and exercise duration and the summed stress score for hard cardiac events.

CONCLUSION

Early poststress (99m)Tc-tetrofosmin LHR has an independent and powerful value in predicting hard and soft cardiac events.

Early post-stress pulmonary uptake of 99mTc tetrofosmin during exercise (SPECT) myocardial perfusion imaging: Correlation with haemodynamic, perfusion and function parameters

OBJECTIVE

To test the association of early post-stress lung/heart ratio (LHR) of 99mTc tetrofosmin radioactivity with gated-SPECT findings and angiographic results.

METHODS

We studied 158 consecutive patients, with stress/rest 99mTc tetrofosmin myocardial SPECT and coronary angiography. Rest scans were obtained as gated SPECT and the left ventricular ejection fraction and end diastolic volume were calculated. To evaluate myocardial ischaemia, we calculated the summed stress score, summed rest score and summed difference score indices. For the LHR calculation, we acquired an anterior image, 4-6 min after radiotracer injection at stress; LHR was defined as mean counts/pixel in the lung region of interest divided by the mean counts/pixel in the myocardial region of interest.

RESULTS

An early post-stress LHR value of 0.500 was defined as the upper normal limit. The most significant correlation (P<0.001) was observed among early post-stress LHR, summed stress score and the number of stenosed vessels. The incidence of multi-vessel coronary artery disease in the subgroup of patients with increased values of early post-stress LHR, was significantly higher than in the normal group (81% vs. 42%, P<0.001). There was a significant difference (P<0.001) of the early post-stress LHR value between patients with normal coronary arteries or one-vessel disease and patients with multi-vessel disease. Early post-stress LHR was an independent predictor of multi-vessel coronary artery disease (coefficient 1.85, SD 0.16, P<0.001), with an incremental value for its identification.

CONCLUSIONS

Our results suggest that early post-stress 99mTc tetrofosmin LHR appears to be a useful index of extensive myocardial ischaemia dysfunction and multi-vessel coronary artery disease.