Assessment of the effect of revascularization early after CABG using ECG-gated perfusion single-photon emission tomography

Chronic non-transmural infarction has a delayed recovery of function following revascularization

BACKGROUND

The time course of regional functional recovery following revascularization with regards to the presence or absence of infarction is poorly known. We studied the effect of the presence of chronic non-transmural infarction on the time course of recovery of myocardial perfusion and function after elective revascularization.

METHODS

Eighteen patients (mean age 69, range 52-84, 17 men) prospectively underwent cine magnetic resonance imaging (MRI), delayed contrast enhanced MRI and rest/stress 99m-Tc-tetrofosmin single photon emission computed tomography (SPECT) before, one and six months after elective coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI).

RESULTS

Dysfunctional myocardial segments (n = 337/864, 39%) were classified according to the presence (n = 164) or absence (n = 173) of infarction. Infarct transmurality in dysfunctional segments was largely non-transmural (transmurality = 31 +/- 22%). Quantitative stress perfusion and wall thickening increased at one month in dysfunctional segments without infarction (p < 0.001), with no further improvement at six months. Despite improvements in stress perfusion at one month (p < 0.001), non-transmural infarction displayed a slower and lesser improvement in wall thickening at one (p < 0.05) and six months (p < 0.001).

CONCLUSIONS

Dysfunctional segments without infarction represent repetitively stunned or hibernating myocardium, and these segments improved both perfusion and function within one month after revascularization with no improvement thereafter. Although dysfunctional segments with non-transmural infarction improved in perfusion at one month, functional recovery was mostly seen between one and six months, possibly reflecting a more severe ischemic burden. These findings may be of value in the clinical assessment of regional functional recovery in the time period after revascularization.

Ischemic cardiomyopathy: a clinical nuclear cardiology perspective

Ischemic cardiomyopathy results from severe extensive coronary artery disease, which is associated with left ventricular dysfunction and also, in many cases, with significant left ventricular dilatation. Mortality is high, especially in patients who satisfy myocardial viability criteria but who have not undergone revascularization. Although age, exercise capacity and comorbidity influence survival, the most important prognostic factors are the extent of the ischemia, myocardial viability and left ventricular remodeling, all of which can be successfully evaluated by gated myocardial perfusion single-photon emission computed tomography (SPECT).

[Predictors of improved left ventricular systolic function after surgical revascularization in patients with ischemic cardiomyopathy]

INTRODUCTION AND OBJECTIVES

Although it is known that the presence of myocardial viability predicts an increase in ejection fraction after revascularization in patients with ischemic cardiomyopathy, little is known about other predictive factors. The aim of this study was to identify variables that can predict an increase in ejection fraction after coronary revascularization surgery in patients with ischemic cardiomyopathy and a viable myocardium.

METHODS

The study included 30 patients (mean age 61.6 [11] years, one female) with ischemic cardiomyopathy (ejection fraction <or=40%) who fulfilled criteria for myocardial viability. All underwent ECG-gated single-photon emission computed tomography before and after surgery.

RESULTS

An increase in ejection fraction >or=5% occurred after surgery in 17 of the 30 patients (56.6%). These patients were characterized by the presence of left main coronary artery disease (P< .004), a large number of grafts (P< .03), a high perfusion summed difference score (P< .012), a low end-diastolic volume (P< .013), and a low end-systolic volume (P< .01). An end-systolic volume <148 mL and a summed difference score >or=4 gave the best predictive model (P=.001, R2=0.73) for an increase in ejection fraction.

CONCLUSIONS

In patients with ischemic cardiomyopathy and a viable myocardium, the main determinants of an increase in ejection fraction after revascularization surgery were low levels of left ventricular remodeling and myocardial ischemia.

Prognostic value of myocardial perfusion gated SPECT in patients with symptomatic intracranial large-artery atherosclerosis

BACKGROUND

We aimed to evaluate the prognostic value of myocardial perfusion gated SPECT in patients with symptomatic intracranial large-artery atherosclerosis (ILA).

METHODS

Seventy-two consecutive first-ever symptomatic ILA patients without known heart disease underwent a stress myocardial perfusion gated SPECT, and long-term follow-up was conducted thereafter.

RESULTS

During an average follow-up of 15.2 +/- 9 months, 9 patients (13.8%) presented major coronary events (CEs). Survival analyses (Kaplan-Meier and Cox regression) identified presence of moderate-to-severe myocardial perfusion defects (log rank p = 0.004) and ejection fraction <50% (p = 0.014) as predictors of future CEs. Neurovascular ischemic events were not predicted by SPECT variables.

CONCLUSION

Myocardial perfusion scintigraphy predicts future CEs in patients with symptomatic ILA and may be helpful to guide therapeutic strategies in this subgroup of stroke patients.

Myocardial viability by contrast-enhanced cardiovascular magnetic resonance in patients with coronary artery disease: comparison with gated single-photon emission tomography and FDG position emission tomography

BACKGROUND

The aim of this study was to assess the value of contrast-enhanced cardiovascular magnetic resonance (CMR) in viability for patients with coronary artery disease and left ventricular (LV) dysfunction (ejection fraction [EF] </=50%), comparing to gated thallium-201 ((201)Tl) single photon emission computed tomography (SPECT) and (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET).

METHODS AND RESULTS

One hundred sixteen patients (EF 37.8 +/- 16.2%) underwent stress-reinjection or rest-redistribution gated-SPECT and CMR (46 FDG-PET) within 1 month. All images were analyzed in a 17-segment and 0-4 scales system. Of 1972 segments, delayed enhancement (DE) on CMR correlated well with (201)Tl reduction (r = 0.90, p < 0.0001). The agreement of SPECT (>/=50% maximal (201)Tl activity) and CMR (</=50% DE) was 96.8% (kappa = 0.62). CMR detected more subendocardial scars in 18 subjects (60 segments). Reduced (201)Tl activity but none DE were observed in 19 subjects (76 segments; more inferior) who had lower EF and larger end-systolic volume (p < 0.05). Of 411 dysfunctional segments from 46 patients, FDG-PET (>/=50% of maximal FDG uptake) detected more viability (9%).

CONCLUSION

The extent of DE correlated (201)Tl activity well. CMR could detect more small infarcts, while FDG-PET could detect more viability. CMR could distinguish between artifacts or infarction on SPECT, especially in poor LV function.

Value of gated SPECT in the analysis of regional wall motion of the interventricular septum after coronary artery bypass grafting

PURPOSE

The aim of this study was the evaluation of septal wall motion, perfusion and wall thickening after CABG in two groups of consecutive patients, one with grafted left anterior coronary artery and no history of myocardial infarction, and the other with previous anteroseptal myocardial infarction and impaired septal motion before surgery. The issue addressed was the ability of gated SPECT to differentiate between true paradoxical septal motion, characterised by paradoxical wall motion, depressed ejection fraction (EF), poor viability and compromised wall thickening, and pseudo-paradoxical motion, characterised by abnormal wall motion and regional EF but preserved perfusion and wall thickening.

METHODS

One hundred and thirty-two patients with previous anterior myocardial infarction, 82 patients with left anterior descending coronary disease and no history of myocardial infarction and 27 normal subjects underwent rest gated SPECT after 99mTc-sestamibi injection, according to the standard QGS protocol. Quantitative regional EF, regional perfusion, regional wall motion and regional wall thickening were determined using a 20-segment model.

RESULTS

Despite the presence of similar regional wall motion impairment in patients with and patients without septal infarction, in terms of regional EF (2.5%+/-3% vs 1.9%+/-4.9% p=NS) and inward septal motion (3+/-4.9 mm vs 2.3+/-6.1 mm p=NS), significant differences were observed in both perfusion (74.7%+/-6.2% vs 63.3%+/-13%, p>0.0001) and regional wall thickening (17.2%+/-7.4% vs 12.6%+/-7.2%, p>0.0001).

CONCLUSION

Gated SPECT with perfusion tracers can reliably differentiate pseudo-paradoxical from true paradoxical septal motion in patients with previous CABG, and it may be the method of choice for evaluating left ventricular performance in this patient population.

Detection of early postoperative internal mammary artery atherosclerosis using Tc-99m myocardial perfusion SPECT imaging

Myocardial perfusion single photon emission computed tomography (SPECT) is a useful noninvasive test to detect the recurrence of myocardial ischemia after coronary artery bypass grafting (CABG). However, the role of myocardial SPECT imaging to detect early recurrence of ischemia after surgery is limited, and its utility in asymptomatic CABG patients remains poorly established.