Non-invasive imaging to identify susceptibility for ventricular arrhythmias in ischaemic left ventricular dysfunction

OBJECTIVE: Non-invasive imaging of myocardial perfusion, sympathetic denervation and scar size contribute to enhanced risk prediction of ventricular arrhythmias (VA). Some of these imaging parameters, however, may be intertwined as they are based on similar pathophysiology. The aim of this study was to assess the predictive role of myocardial perfusion, sympathetic denervation and scar size on the inducibility of VA in patients with ischaemic cardiomyopathy in a head-to-head fashion. METHODS: 52 patients with ischaemic heart disease and left ventricular ejection fraction (LVEF) ≤35%, referred for primary prevention implantable cardioverter-defibrillator (ICD) implantation, were included. Late gadolinium-enhanced cardiovascular MRI was performed to assess LV volumes, function and scar size. Using [(15)O]H2O and [(11)C]hydroxyephedrine positron emission tomography, both resting and hyperaemic myocardial blood flow (MBF), and sympathetic innervation were assessed. After ICD implantation, an electrophysiological study (EPS) was performed and was considered positive in case of sustained VA. RESULTS: Patients with a positive EPS (n=25) showed more severely impaired global hyperaemic MBF (p=0.003), larger sympathetic denervation size (p=0.048) and tended to have larger scar size (p=0.07) and perfusion defect size (p=0.06) compared with EPS-negative patients (n=27). No differences were observed in LV volumes, LVEF and innervation-perfusion mismatch size. Multivariable analysis revealed that impaired hyperaemic MBF was the single best independent predictor for VA inducibility (OR 0.78, 95% CI 0.65 to 0.94, p=0.007). A combination of risk markers did not yield incremental predictive value over hyperaemic MBF alone. CONCLUSIONS: Of all previously validated approaches to evaluate the arrhythmic substrate, global impaired hyperaemic MBF was the only independent predictor of VA inducibility. Moreover, a combined approach of different imaging variables did not have incremental value.