Relationship between left ventricular dyssynchrony and scar burden in the genesis of ventricular tachyarrhythmia.

BACKGROUND: Left ventricular (LV) ejection fraction (EF) has poor predictive value for ventricular tachyarrhythmia (VT). Other parameters such as LV dyssynchrony (LVD), and LV scar burden have also been individually associated with VT, but the interplay of these factors in the genesis of VT has not been explored. This retrospective study sought to evaluate the relationship between LVD and imaging characteristics of the myocardial substrate in predicting VT.

METHODS: We identified 183 patients (150 men; mean age: 64 ± 14 years and mean LVEF: 23% ± 7%), who received an implantable cardioverter defibrillator (ICD) for primary prevention and who underwent a gated single-photon emission computed tomography (GSPECT) myocardial perfusion scan prior to ICD implantation. LVD was determined by phase analysis of the GSPECT images. Occurrence of VTs was established through routine ICD interrogations and review of electronic medical records.

RESULTS: LVD was present in 136 (74%) patients. VT occurred in 48 (26%) patients. Ninety-eight percent of patient who experienced VT had LVD. Patients without LVD had a significantly better survival free of both sustained and non-sustained VT (HR, 95% CI 4.90, 2.12-11.20; P < 0.0001). The combination of LVD and myocardial scar occupying > 6% of LV myocardium accounted for 83% of all VT events.

CONCLUSIONS: LVD assessment by GSPECT is strongly associated with incident VT in patients with low LVEF. The combination of LVD and scar burden predicted the majority of VT events.