Simultaneous assessment of left ventricular perfusion and function with technetium-99m sestamibi after coronary artery bypass grafting

When to stress patients after coronary artery bypass surgery? Risk stratification in patients early and late post-CABG using stress myocardial perfusion SPECT: implications of appropriate clinical strategies

OBJECTIVES

The study compared the prognostic significance of myocardial perfusion single-photon emission computed tomography (SPECT) (MPS) in patients early and late after coronary artery bypass graft surgery (CABG).

BACKGROUND

The long-term effectiveness of CABG is limited by graft stenosis. The greatest incidence of graft occlusion occurs between five and eight years after surgery. However, little is known regarding the appropriate time to stress patients post-CABG with respect to risk stratification.

METHODS

We identified 1,765 patients, who underwent MPS 7.1 +/- 5.0 years post-CABG. All patients underwent rest T1-201/stress Tc-99m sestamibi MPS and were followed up > or =1 year after testing. Patients with early CABG or PTCA (<60 days after MPS) were censored. The prognostic population consisted of 1,544 patients. A semiquantitative visual analysis employing a 20-segment model was used to define summed stress score (SSS), summed rest score (SRS), summed difference score (SDS), and the number of nonreversible segments (NRS).

RESULTS

During follow-up, 53 cardiac deaths (CD) occurred. There was a significant increase in annual CD rates as a function of SSS. A multivariate analysis identified age, ischemia (SDS), and infarct size (NRS) as independent predictors of CD. Nuclear variables added incremental value to prescan information. The annual CD rate was relatively low (1.3%) in patients < or =5 years post-CABG. In this subgroup only age and infarct size (NRS) were predictive of CD.

CONCLUSION

MPS is strongly predictive of subsequent CD in post-CABG patients and adds incremental value over clinical and treadmill test information. Our data suggest that symptomatic patients < or =5 years and all patients >5 years post-CABG may benefit from testing.

A New Position for Photoplethysmography Assessment of Lower Leg Venous Function-Technical Notes

A new position for photoplethysmographic (PPG) assessment of lower leg venous function is described and tested. This study aids in the selection of patients for more limited stripping operation. PPG measurements were carried out in the usual sitting position and in the supine body position on limbs with primary varicose veins. Competence of the greater saphenous vein (GSV) and incompetent perforators were evaluated by venography. Limbs with a competent GSV in the lower leg had a longer 50% venous refill time (VRT/2) in the supine body position than in the sitting position (7.6 +/- 0.6 seconds vs 5.0 +/- 0.4 seconds, p < 0.01). Limbs without incompetent perforators had a longer VRT/2 in the supine body position than in the sitting position (8.0 +/- 1.1 seconds vs 5.1 +/- 0.3 seconds, p < 0.05). PPG measurement in the supine body position gave a better separation of VRT/2s on GSV competence in the lower leg and incompetent perforators. The supine body position is recommended for assessing lower leg venous function.

Prediction of outcome of patients with life-threatening ventricular arrhythmias treated with automatic implantable cardioverter-defibrillators using SPECT perfusion imaging

BACKGROUND

In the present study, we examined the predictors of outcome of 103 patients with coronary artery disease and left ventricular dysfunction who had life-threatening ventricular arrhythmias and were treated with implantable cardioverter-defibrillators with the use of single-photon emission computed tomography (SPECT).

METHODS AND RESULTS

During a mean follow-up of 29 months, there were 29 cardiac deaths. In comparison with patients who died, survivors had less diabetes mellitus (45% versus 19%, P < .007), higher left ventricular ejection fraction (23 +/- 9% versus 27 +/- 11%, P = .04), and fewer perfusion defects as determined with stress SPECT (15 +/- 5 versus 12 +/- 5, P < .004). Most of the perfusion defects were fixed, indicative of scarring; the extent of reversible defects did not differ (2 +/- 3 in survivors and 3 +/- 4 in nonsurvivors). Multivariate Cox survival analysis identified the number of fixed defects as the only independent predictor of death (chi 2 = 10, P = .002). There were six deaths among 42 patients (14%) with < 8 fixed defects compared with 23 deaths among 61 patients (38%) with > or = 8 defects (P = .005). The 4-year survival was better in patients with < 8 segmental fixed defects than in those with > or = 8 fixed defects (80% versus 36%) (chi 2 = 8, P = .005).

CONCLUSIONS

The myocardial perfusion pattern is an important determinant of outcome in patients with life-threatening ventricular arrhythmias who are treated with a implantable cardioverter-defibrillator. The extent of scarring separates patients into high- and low-risk groups with a 2.7-fold difference in death rate.

Prognostic value of simultaneous perfusion and function assessment using technetium-99m sestamibi

This study examines the prognostic value of simultaneous perfusion and function assessment in 412 patients. The exercise perfusion pattern was a stronger predictor of events (mostly acute nonfatal myocardial infarcts) than resting ejection fraction.