Prognostic value of revascularising viable myocardium in elderly patients with stable coronary artery disease and left ventricular dysfunction: a PET/CT study

Utility of coronary revascularization in patients with ischemic left ventricular dysfunction

BACKGROUND

Revascularization in patients with left ventricular (LV) dysfunction has been a subject of ongoing uncertainty and conflicting results. This is further complicated by factors including viability, severity of LV dysfunction, and method of revascularization using percutaneous coronary intervention (PCI) versus coronary-artery bypass grafting (CABG).

OBJECTIVES

The purpose of this meta-analysis is to evaluate the association of coronary revascularization with outcomes in patients with ischemic LV dysfunction.

METHODS

A literature search was conducted for studies reporting on cardiovascular outcomes after revascularization compared to optimal medical therapy (OMT) in patients with ischemic LV dysfunction.

RESULTS

A total of 23 studies with 10,110 participants met inclusion criteria. Revascularization was significantly associated with lower all-cause mortality and CV mortality compared to OMT. The association was statistically significant regardless of severity of LV dysfunction or method of revascularization. Subgroup analysis demonstrated that revascularization was significantly associated with lower all-cause and CV mortality compared to OMT for patients with viable myocardium and mixed cohorts with variable viability, but not patients without viable myocardium. Revascularization was not associated with a significant difference in risk of heart failure (HF) hospitalization or acute myocardial infarction (AMI) compared to OMT.

CONCLUSIONS

Revascularization in patients with ischemic LV dysfunction is associated with lower risk of all-cause and CV mortality independent of severity of LV dysfunction or method of revascularization. Revascularization is not associated with lower risk of mortality in patients without evidence of viable myocardium and is not associated with lower risk of AMI or HF hospitalization.

Cardiovascular positron emission tomography: established and emerging role in cardiovascular diseases

Cardiac positron emission tomography (PET) imaging has established themselves firmly as excellent and reliable functional imaging modalities in assessment of the spectrum of coronary artery disease. With the explosion of technology advances and the dream of flow quantification now a reality, the value of PET is now well realized. Cardiac PET has proved itself as precise imaging modality that provides functional imaging of the heart in addition to anatomical imaging. It has established itself as one of the best available techniques for evaluation of myocardial viability. Hybrid PET/computed tomography provides simultaneous integration of coronary anatomy and function with myocardial perfusion and metabolism, thereby improving characterization of the dysfunctional area and chronic coronary artery disease. The availability of quantitative myocardial blood flow evaluation with PET provides additional prognostic information and increases diagnostic accuracy in the management of patients with coronary artery disease. Hybrid imaging seems to hold immense potential in optimizing management of cardiovascular diseases and furthering clinical research.

Rescue Protocol to Improve the Image Quality of 18F-FDG PET/CT Myocardial Metabolic Imaging

PURPOSE

18F-FDG PET myocardial metabolic imaging is used to estimate myocardial viability. However, poor image quality can affect the accurate quantification of viable myocardium. We assessed the feasibility of a rescue protocol that reinjected low-dose 18F-FDG with simultaneous 1 to 2 U of insulin injection and oral administration of 10 g of glucose to improve the image quality of 18F-FDG PET myocardial metabolic imaging.

PATIENTS AND METHODS

Fifty-one consecutive patients with poor quality to uninterpretable 18F-FDG PET/CT myocardial metabolic images received the rescue protocol immediately after the initial image acquisition. The postrescue image acquisition was performed 1 hour later. The rescue image quality was compared with the initial image. The qualitative visual estimation of the images was graded as follows: grade 0, homogeneous, minimal uptake; grade 1, predominantly minimal or mild uptake; grade 2, moderate uptake; and grade 3, good uptake. The myocardium-to-blood pool activity ratio (M/B) was measured to assess the image quality quantitatively.

RESULTS

The grades of 0 to 3 were observed in 24 (47%), 27 (53%), 0 (0%), and 0 (0%) patients, respectively, for the initial imaging, and in 0 (0%), 3 (5.9%), 4 (7.8%), and 44 (86.3%) patients for the rescue imaging (P < 0.001). The rescue M/B was significantly higher than the initial M/B (3.4 ± 1.4 vs 1.6 ± 0.6, respectively; P < 0.001).

CONCLUSIONS

The rescue protocol successfully and rapidly improved the quality of myocardial 18F-FDG metabolic imaging.

Positron Emission Tomography in the Diagnosis and Management of Coronary Artery Disease

Cardiac positron emission tomography (PET) and positron emission tomography/computed tomography (PET/CT) are encouraging precise non-invasive imaging modalities that allow imaging of the cellular function of the heart, while other non-invasive cardiovascular imaging modalities are considered to be techniques for imaging the anatomy, morphology, structure, function and tissue characteristics. The role of cardiac PET has been growing rapidly and providing high diagnostic accuracy of coronary artery disease (CAD). Clinical cardiology has established PET as a criterion for the assessment of myocardial viability and is recommended for the proper management of reduced left ventricle (LV) function and ischemic cardiomyopathy. Hybrid PET/CT imaging has enabled simultaneous integration of the coronary anatomy with myocardial perfusion and metabolism and has improved characterization of dysfunctional areas in chronic CAD. Also, the availability of quantitative myocardial blood flow (MBF) evaluation with various PET perfusion tracers provides additional prognostic information and enhances the diagnostic performance of nuclear imaging.