Abstract
22
Objectives Myocardial infarction (MI) results in sympathetic denervation of the scar and adjacent areas, which is associated with sudden cardiac death. Sympathetic denervation has also been observed in patients with chronic multi-vessel coronary artery disease but without MI, suggesting that perfusion abnormalities lead to sympathetic nerve injury. Impaired hyperemic myocardial blood flow (MBF), reflecting subtle perfusion abnormalities may therefore be associated with sympathetic nerve injury in non-infarcted myocardium. The aim of this study was to assess the relation of positron emission tomography (PET) assessed sympathetic innervation and hyperemic MBF in non-infarcted myocardium.
Methods 44 patients with ischemic cardiomyopathy, referred for primary prevention ICD implantation according to current guidelines were included (38 men, age 67±8 years, LVEF 29±6%). [15O]H2O- and [11C]Hydroxyephedrine (HED)-PET was performed to quantify resting MBF, hyperemic MBF, and sympathetic innervation. Late gadolinium enhanced-cardiac magnetic resonance (LGE-CMR) imaging was performed to assess left ventricular end-systolic (LVESV) and end-diastolic volumes (LVEDV), and scar size. HED retention index (RI) and MBF were assessed in remote segments, selected on LGE-CMR results.
Results In non-infarcted myocardium, HED RI positively correlated with hyperemic MBF (R=0.45, p<0.01), resting MBF (R=0.31, p=0.04), and negatively with LVESV (R=-0.32, p=0.03) and LVEDV (R=-0.36, p=0.02). Multivariate linear regression analysis revealed that hyperemic MBF (B=0.68 p<0.01), LVEDV (B=-.005, p=0.01), and NTproBNP (B=-0.24, p=0.04) were independently associated with HED RI in remote myocardium.
Conclusions Sympathetic innervation is related with hyperemic MBF in non-infarcted myocardium in patients with ischemic cardiomyopathy. Whether impaired hyperemic MBF is the primary cause of this relation remains unclear.