Multielectrode Mapping Versus Point-by-Point Mapping for Catheter Ablation of Ventricular Tachycardia: A Systematic Review and Meta-Analysis

Comparison of the arrhythmogenic substrate for ventricular tachycardia in patients with ischemic vs non-ischemic cardiomyopathy - insights from high-density, multi-electrode catheter mapping

PURPOSE

The purpose of this study was to compare the differences of arrhythmogenic substrate using high-density mapping in ventricular tachycardia (VT) patients with ischemic (ICM) vs non-ischemic cardiomyopathy (NICM).

METHODS

Data from patients presenting for VT ablation from December 2016 to December 2020 at Westmead Hospital were reviewed.

RESULTS

Sixty consecutive patients with structural heart disease (ICM 57%, NICM 43%, mean age 66 years) having catheter ablation of scar-related VT with pre-dominant left ventricular involvement were included. ICM was associated with larger proportion of dense scar area (bipolar; 19 [12-29]% vs 6 [3-10]%, P < 0.001, unipolar; 20 [12-32]% vs 11 [7-19]%, P = 0.01) compared with NICM. However, the scar ratio (unipolar dense scar [%]/bipolar dense scar [%]) was significantly higher in NICM patients (1.2 [0.8-1.7] vs 1.7 [1.3-2.3], P = 0.003). Larger scar area in ICM was paralleled by higher proportion of complex electrograms (6 [2-13] % vs 3 [1-5] %, P = 0.01), longer and wider voltage based conducting channels, higher incidence of late potential-based conducting channels, longer VT cycle-length (399 ± 80 ms vs 359 ± 68 ms, P = 0.04) and greater maximal stimulation-QRS interval among sites with good pace-map correlation (75 [51-99]ms vs 48 [31-73]ms, P = 0.02). Ventricular arrhythmia (VA) storm was more highly prevalent in ICM than NICM (50% vs 23%, P = 0.03). During the follow-up period, NICM had a significantly higher cumulative incidence for the VA recurrence than ICM (P = 0.03).

CONCLUSIONS

High-density multi-electrode catheter mapping of left ventricular arrhythmogenic substrate of NICM tends to show smaller dense scar area and higher scar ratio, compared with ICM, suggestive the extent of epicardial/intramural substrate, with paucity of substrate targets for ablation, which results in the worse outcomes with ablation.

Contemporary Management of Complex Ventricular Arrhythmias

Percutaneous catheter ablation is an effective and safe therapy that can eliminate ventricular tachycardia, reducing the risks of both recurrent arrhythmia and shock therapies from a defibrillator. Successful ablation requires accurate identification of arrhythmic substrate and the effective delivery of energy to the targeted tissue. A thorough pre-procedural assessment is needed before considered 3D electroanatomical mapping can be performed. In contemporary practice, this must combine traditional electrophysiological techniques, such as activation and entrainment mapping, with more novel physiological mapping techniques for which there is an ever-increasing evidence base. Novel techniques to maximise energy delivery to the tissue must also be considered and balanced against their associated risks of complication. This review provides a comprehensive appraisal of contemporary practice and the evidence base that supports recent developments in mapping and ablation, while also considering potential future developments in the field.

Management of ventricular tachycardia in patients with ischaemic cardiomyopathy: contemporary armamentarium

Worldwide, ∼4 million people die from sudden cardiac death every year caused in more than half of the cases by ischaemic cardiomyopathy (ICM). Prevention of sudden cardiac death after myocardial infarction by implantation of a cardioverter-defibrillator (ICD) is the most common, even though not curative, therapy to date. Optimized ICD programming should be strived for in order to decrease the incidence of ICD interventions. Catheter ablation reduces the recurrence of ventricular tachycardias (VTs) and is an important adjunct to sole ICD-based treatment or pharmacological antiarrhythmic therapy in patients with ICM, as conclusively demonstrated by seven randomized controlled trials (RCTs) in the last two decades. However, none of the conducted trials was powered to reveal a survival benefit for ablated patients as compared to controls. Whereas thorough consideration of an early approach is necessary following two recent RCTs (PAUSE-SCD, BERLIN VT), catheter ablation is particularly recommended in patients with recurrent VT after ICD therapy. In this context, novel, pathophysiologically driven ablation strategies referring to deep morphological and functional substrate phenotyping based on high-resolution mapping and three-dimensional visualization of scars appear promising. Emerging concepts like sympathetic cardiac denervation as well as radioablation might expand the therapeutical armamentarium especially in patients with therapy-refractory VT. Randomized controlled trials are warranted and on the way to investigate how these translate into improved patient outcome. This review summarizes therapeutic strategies currently available for the prevention of VT recurrences, the optimal timing of applicability, and highlights future perspectives after a PAUSE in BERLIN.