Regional myocardial sympathetic denervation predicts the risk of sudden cardiac arrest in ischemic cardiomyopathy.

Objectives: The PAREPET (Prediction of ARrhythmic Events with Positron Emission Tomography) study sought to test the hypothesis that quantifying inhomogeneity in myocardial sympathetic innervation could identify patients at highest risk for sudden cardiac arrest (SCA).

Background: Left ventricular ejection fraction (LVEF) is the only parameter identifying patients at risk of SCA who benefit from an implantable cardiac defibrillator (ICD).

Methods: We prospectively enrolled 204 subjects with ischemic cardiomyopathy (LVEF ≤35%) eligible for primary prevention ICDs.

An abbreviated hyperinsulinemic-euglycemic clamp results in similar myocardial glucose utilization in both diabetic and non-diabetic patients with ischemic cardiomyopathy.

Background: Positron emission tomography (PET) with insulin-stimulated (18)F-2-deoxyglucose (FDG) uptake is the gold standard for myocardial viability. However, insulin stimulation is infrequently performed due to time and inconvenience. We therefore assessed the clinical applicability of an abbreviated hyperinsulinemic-euglycemic clamp.

The Selvester QRS Score is more accurate than Q waves and fragmented QRS complexes using the Mason-Likar configuration in estimating infarct volume in patients with ischemic cardiomyopathy.

Infarct volume independently predicts cardiovascular events. Fragmented QRS complexes (fQRS) may complement Q waves for identifying infarction; however, their utility in advanced coronary disease is unknown. We tested whether fQRS could improve the electrocardiographic prediction of infarct volume by positron emission tomography in 138 patients with ischemic cardiomyopathy (ejection fraction, 0.

Prediction of arrhythmic events with positron emission tomography: PAREPET study design and methods.

Background: In medically-treated patients with ischemic cardiomyopathy, myocardial viability is associated with a worse prognosis than scar. The risk is especially great with hibernating myocardium (chronic regional dysfunction with reduced resting flow), and the excess mortality appears to be due to sudden cardiac death (SCD). Hibernating myocardium also results in sympathetic nerve dysfunction, which has been independently associated with risk of SCD.

Regional 11C-hydroxyephedrine retention in hibernating myocardium: chronic inhomogeneity of sympathetic innervation in the absence of infarction.

Unlabelled: We have previously shown that ex vivo counting of (131)I-metaiodobenzylguanidine can identify regional reductions in sympathetic norepinephrine uptake in pigs with hibernating myocardium. However, nonneuronal uptake limited relative differences between regions and would preclude accurate assessment with conventional imaging. We therefore hypothesized that the superior specificity of the positron-emitting isotope (11)C-hydroxyephedrine (HED) would facilitate the imaging of regional differences, and we designed this study to determine whether altered uptake of norepinephrine by sympathetic nerves in viable, dysfunctional myocardium can be imaged in vivo and to determine the temporal progression and stability of sympathetic dysinnervation in hibernating myocardium.

Spatial inhomogeneity of sympathetic nerve function in hibernating myocardium.

Background: Although humans and swine with hibernating myocardium have an increased risk of sudden death, the contribution of chronic alterations in sympathetic nerve function is unknown. Acute transmural ischemia causes inhomogeneity in sympathetic innervation that may lead to lethal arrhythmias, but it is unclear whether similar abnormalities develop in response to chronic reversible ischemia.

Methods And Results: Swine were chronically instrumented with a left anterior descending coronary artery (LAD) stenosis that produced hibernating myocardium after 3 months.