Catheter Ablation of Multiple Ventricular Tachycardias After Myocardial Infarction Guided by Combined Contact and Noncontact Mapping

Abstract

Background-Insights gained from noncontact mapping of ventricular tachycardia (VT) have not been systematically applied to contact maps. This study sought to unify both techniques for an individualized approach to the patient with multiple ischemic VTs irrespective of cycle length. Methods and Results-For 12 consecutive patients with chronic myocardial infarction and recurrent VT, bipolar contact maps were acquired during sinus or paced rhythm. Additional noncontact maps were obtained during 48 induced VTs (cycle length 192 to 579 ms). Endocardial exit sites were superimposed on contact maps and verified by pace-mapping. Radiofrequency lesions were extended for critical borders defined by multiple neighboring exits and followed the isovoltage contour line of contact maps. Nine critical borders were identified in 8 patients and constituted the substrate for 31 VTs. The voltage at exit sites was 0.8 mV (range 0.1 to 2.3). Noncontact maps revealed 23Ϯ18% of isthmus conduction. Thirty-seven (77%) of all and 83% of clinically documented VTs were rendered noninducible irrespective of cycle length by application of 27 radiofrequency lesions (range 18 to 56). Spontaneous transitions between distinct VTs along critical borders were demonstrated in 4 patients. Pace-mapping reproduced the QRS morphology of 81% of VTs and was associated with successful ablation (PϽ0.01). Noninducibility of any sustained VT was reached for 8 (67%) patients. During 15 months (range 5 to 28) of follow-up, 8 patients remained without recurrence, and VT episodes were reduced in the other 4 patients (PϽ0.01). VT cycle length was not predictive for acute or long-term success. Conclusion-The combined approach of contact and noncontact mapping effectively defines critical borders as the substrate of multiple VTs without limitation for unstable VTs.

Evolution of Ventricular Tachycardia and Its Electrophysiological Substrate Early After Myocardial Infarction

“…The amount of isthmus conduction mapped was defined as the percentage of the time interval from the earliest endocardial activity to QRS onset. 11 Statistical analysis was performed using SPSS version 16 (SPSS Inc, Chicago, IL). All descriptive continuous results are expressed as mean±2 SD or median (interquartile range).…”

Elimination of Local Abnormal Ventricular Activities

“…Current ablation strategies often rely on the ability to identify a reentrant circuit and to target a critical isthmus through activation and entrainment mapping. [1][2][3][4][5] A reliably inducible, well-tolerated, and single monomorphic VT is ideal but unfortunately not the rule. Factors such as noninducibility or poor hemodynamic tolerance may render the VT unmappable.…”

Sustained ventricular tachycardia in structural heart disease

“…Areas of scar, healthy and viable myocardium (voltage map) as well as regions near to and far from the site of origin of the tachycardia (activation and propagation maps) can be identified and displayed by color-coding (Fig. 5) [66,67]. This information, in conjunction with intracardiac recordings and entrainment techniques, is a valuable guide for VT ablation and contributes decisively to the success of the procedure.…”