Abstract
Background: Antitachycardia pacing (ATP) is the primary treatment for sustained ventricular tachycardia (VT), resulting in a reduction in ICD shocks. Patients who fail ATP have increased mortality compared to ATP responders. Myocardial scarring by cMR and left ventricular dysynchrony (LVD) by nuclear imaging are associated with a higher risk for VT. We hypothesized that scar and dyssynchrony can predict response to ATP. Methods: We identified 119 patients with sustained VT from 2008-2012, who received ICD therapy with preprogrammed ATP delivery and had a single photon emission computed tomography (SPECT) myocardial perfusion study. Semi-quantitative visual scoring with a 17-segment model was used and the summed stress, rest and difference scores were calculated to measure abnormal myocardium, scar and ischemia. LVD was measured in gated studies (n=59), using the established phase analysis (PA) methodology. Phase standard deviation (PSD) and histogram bandwidth (HBW) were compared between groups using chi-square analysis. Results: Of 119 patients (105 men, mean age: 75.8±18.2y), 82 (68%) had successful ATP. Normal myocardial perfusion was more commonly found in ATP-responders (10.5% vs. 19.8%, p=0.29). There was no difference in the presence of ischemia between the two groups. Phase SD (13.5±6.2 vs. 9.0±5.4, p=0.009) and HBW (54.5±27.1 vs. 37.9±25.2, p = 0.03) were significantly higher among ATP responders. In both a univariate and multivariate logistic regression analysis phase SD (OR, 95% CI: 1.85, 1.09-3.15, p=0.02) was an independent predictor of ATP success. Conclusions: LV dyssynchrony but not scar burden was associated with ATP responsiveness. These results are hypothesis generating for a role of LV dyssynchrony in the prediction of ATP responsiveness.
Published Version
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