Predictors of ventricular ablation's success: Viability, innervation, or mismatch?

AIMS: Sympathetic dys-innervation may play an important role in the development of post-ischemic ventricular arrhythmias (VA). Aim of this study was to prove that perfusion/innervation mismatch (PIM) evaluated by SPECT can identify areas of local abnormal ventricular activities (LAVA) on electroanatomic mapping (EAM). METHODS: Sixteen patients referred to post-ischemic VA catheter ablation underwent pre-procedural and 1-month post-ablation 123I-MIBG/99mTc-tetrofosmin rest SPECT myocardial imaging. PIM was defined according to the segmental distributions of 99mTc-tetrofosmin and 123I-MIBG. A 17-segment LV analysis was used for either SPECT or LV EAM voltage map. All patients were followed up clinically for at least 1 year. RESULTS: Before ablation, the mean voltage in the PIM segments was higher than in the scarred ones but lower than in the normal regions. The presence of PIM in a specific LV zone was an independent predictor of LAVA. After ablation, PIM value was significantly reduced, mainly due to an increase in perfusion summed rest score, in particular in patients that were responders to ablation. CONCLUSIONS: PIM may associate with VA substrate expressed by LAVA and might provide a novel guide for substrate ablation. A significant reduction of PIM could predict a positive clinical response to ablation.

Relationships between cardiac innervation/perfusion imbalance and ventricular arrhythmias: impact on invasive electrophysiological parameters and ablation procedures.

PURPOSE: To assess the relationship between regional myocardial perfusion and sympathetic innervation parameters at myocardial scintigraphy and intra-cavitary electrophysiological data in patients with ventricular arrhythmias (VA) submitted to invasive electrophysiological study and ablation procedure. METHODS: Sixteen subjects underwent invasive electrophysiological study with electroanatomical mapping (EAM) followed by trans-catheter ablations of VA. Before ablation all patients were studied with a combined evaluation of regional myocardial perfusion and sympathetic innervation by means of tomographic 99mTc-tetrofosmin and 123I- metaiodobenzylguanidine cadmium-zinc-telluride (CZT) scintigraphies, respectively. Off-line spatial co-registration of CZT perfusion and innervation data with the three-dimensional EAM reconstruction was performed in every patient. RESULTS: CZT revealed the presence of myocardial scar in 55 (20 %) segments. Of the viable myocardial segments, 131 (60 %) presented a preserved adrenergic innervation, while 86 (40 %) showed a significantly depressed innervation (i.e. innervation/perfusion mismatch). On EAM, the invasively measured intra-cavitary voltage was significantly lower in scarred segments than in viable ones (1.7 ± 1.5 mV vs. 4.0 ± 2.2 mV, P < 0.001). Interestingly, among the viable segments, those showing an innervation/perfusion mismatch presented a significantly lower intra-cavitary voltage than those with preserved innervation (1.9 ± 2.5 mV vs. 4.7 ± 2.3 mV, P < 0.001). Intra-cardiac ablation was performed in 63 (23 %) segments. On multivariate analysis, after correction for scar burden, the segments showing an innervation/perfusion mismatch remained the most frequent ablation targets (OR 5.6, 95 % CI 1.5-20.8; P = 0.009). CONCLUSIONS: In patients with VA, intra-cavitary electrical abnormalities frequently originate at the level of viable myocardial segments with depressed sympathetic innervation that frequently represents the ultimate ablation target.