Irrigated Radiofrequency Catheter Ablation Guided by Electroanatomic Mapping for Recurrent Ventricular Tachycardia After Myocardial Infarction

Abstract

Background-Recurrent ventricular tachycardia (VT) is an important cause of mortality and morbidity late after myocardial infarction. With frequent use of implantable cardioverter-defibrillators, these VTs are often poorly defined and not tolerated for mapping, factors previously viewed as relative contraindications to ablation. This observational multicenter study assessed the outcome of VT ablation with a saline-irrigated catheter combined with an electroanatomic mapping system. Methods and Results-Two hundred thirty-one patients (median LV ejection fraction, 0.25; heart failure in 62%) with recurrent episodes of monomorphic VT (median, 11 in the preceding 6 months) caused by prior myocardial infarction were enrolled. All inducible monomorphic VTs with a rate approximating or slower than any spontaneous VTs were targeted for ablation guided by electroanatomic mapping during sinus rhythm and/or VT. Patients were not excluded for multiple VTs (median, 3 per patient) or unmappable VT (present in 69% of patients). Ablation abolished all inducible VTs in 49% of patients. The primary end point of freedom from recurrent incessant VT or intermittent VT after 6 months of follow-up was achieved for 123 patients (53%). In 142 patients with implantable cardioverter-defibrillators before and after ablation for intermittent VT who survived 6 months, VT episodes were reduced from a median of 11.5 to 0 (PϽ0.0001). The 1-year mortality rate was 18%, with 72.5% of deaths attributed to ventricular arrhythmias or heart failure. The procedure mortality rate was 3%, with no strokes. Conclusions-Catheter ablation is a reasonable option to reduce episodes of recurrent VT in patients with prior myocardial infarction, even when multiple and/or unmappable VTs are present. This population remains at high risk for death, warranting surveillance and further study. (Circulation. 2008;118:2773-2782.)

Lesion Formation by Ventricular Septal Ablation With Irrigated Electrodes - Comparison of Bipolar and Sequential Unipolar Ablation -

“…4 Sivagangabalan et al studied intraseptal VT in a chronic ovine infarct model using contact and noncontact mapping from the RV and LV, and they showed that septal VTs usually had a common intramural isthmus capable of exciting either ventricle, with a very short delay between the earliest LV and RV activations. 8 In their study, the initial RF energy delivery was directed along the septum in the ventricle with the earliest breakout.…”

“…Using bipolar ablation may simplify the treatment of VT originating from the IVS and associated with structural heart disease. 4 Ablation of deep septal re-entrant circuits that may be responsible for VT ablation failure remains a challenge. An effective, reproducible ablation strategy, such as the bipolar ablation strategy used in our study, will likely improve the success rate of septal VT ablation.…”

Correlation of Scar in Cardiac MRI and High‐Resolution Contact Mapping of Left Ventricle in a Chronic Infarct Model

“…Activation mapping is not possible for the majority of the tachycardias (unmappable), either because of hemodynamic instability during the tachycardia or because the tachycardia is not sustained, not reinducible, or changes to another tachycardia before mapping can be completed 1. The substrate for the multiple reentrant circuits is the interconnecting network of surviving myocardial bundles within the scar 2.…”

Ranolazine: safe and effective in a patient with hypertensive cardiomyopathy and multiple episodes of electrical storm

“…Although short‐term effectiveness of drug therapy is generally high, especially with the addition of mexiletine 5 in resistant cases, toxicity with multiple side effects of both amiodarone and mexiletine attenuates the favorable outcomes in the long term. Radiofrequency (RF) ablation is routinely applied in patients with ICD and drug‐refractory VA, but its long‐term efficacy is also not too high 6, 7. Thus, a small subgroup of ICD recipients develops drug‐ and ablation‐refractory VA.…”