Abstract 4117: A Comparison of Cardiac MRI Peri-Infarct Border Zone Quantification Strategies for the Prediction of Ventricular Tachycardia Inducibility
Peri-infarct border zone (BZ) as quantified by delayed-enhancement cardiac MRI (CMR) has been proposed as a risk stratification tool, and is associated with increased mortality, but has been measured by various methods in the literature. We assessed which BZ analysis best predicts inducible arrhythmia during electrophysiological study (EPS).
Methods: CMR was performed in 47 patients with CAD referred for EPS to assess for ventricular tachyarrhythmias (VT). CMR data was analyzed for BZ quantification by three methods. Method I used pixels 2–3 standard deviations over the mean of normal tissue, expressed as % of LV mass. Method II (Yan) used the same pixels but is expressed as % of infarct size. Method III (Schmidt) used a full-width, half-max method. EPS results were classified as negative (non-inducible) or positive (monomorphic VT). Patients with indeterminate EPS outcomes (VF or polymorphic VT, n=9) were not included in this analysis.
Results: There were 38 subjects-age 60.2 ± 10.8 yrs, 68% male. During EPS, 20 patients were non-inducible and 18 had induced monomorphic VT (MVT). EF was not significantly different between non-inducible patients and those with MVT (33.4 ± 11.9% vs. 28.1 ± 9.3, p=0.13). Infarct size was significantly different (15.0 ± 11.6% vs. 26.4 ± 12.0%, p = 0.005). BZ by method I was significantly different (1.4 ± 1.3% vs. 3.1 ± 1.5%, p = 0.001), but not by method II (15.2 ± 21.3% vs. 8.0 ± 4.8%, p = 0.17) or method III (4.1 ± 4.5g vs. 3.7 ± 3.7g, p = 0.756). Multivariate analysis demonstrated that BZ by method I was an independent predictor of EPS outcome after controlling for infarct size (OR 1.97 per % change, 95% CI 1.04 to 3.73, p = 0.04). Method I BZ remained an independent predictor when controlling for both infarct size and EF, (OR 2.12 per % change, 95% CI 1.06 to 34.22, p = 0.03). Correlation between techniques was variable (Method I vs. Method II R=0.77, p=0.001; Method I vs. Method III R=0.03, p=0.86; Method II vs. Method III R=0.15, p<0.32).
Conclusion: This study demonstrates significant variability between the published methods for measuring BZ. We also show that large BZ by Method I is a stronger predictor of inducible MVT during EPS than EF and infarct size. BZ may be yet another CMR marker of elevated risk of arrhythmia, but requires more rigorous definition.