The impact of ultra-high-density mapping on long-term outcome after catheter ablation of ventricular tachycardia

Abstract

Ultra-high-density (UHD) mapping can improve scar area detection and fast activation mapping in patients undergoing catheter ablation of ventricular tachycardia (VT). The aim of the present study was to compare the outcome after VT ablation guided by UHD and conventional point-by-point 3D-mapping. The acute and long-term ablation outcome of 61 consecutive patients with UHD mapping (64-electrode mini-basket catheter) was compared to 61 consecutive patients with conventional point-by-point 3D-mapping using a 3.5 mm tip catheter. Patients, whose ablation was guided by UHD mapping had an improved 24-months outcome in comparison to patients with conventional mapping (cumulative incidence estimate of the combination of recurrence or disease-related death of 52.4% (95% confidence interval (CI) [36.9-65.7]; recurrence: n = 25; disease-related death: n = 4) versus 69.6% (95% CI [55.9-79.8]); recurrence: n = 31; disease-related death n = 11). In a cause-specific Cox proportional hazards model, UHD mapping (hazard ratio (HR) 0.623; 95% CI [0.390-0.995]; P = 0.048) and left ventricular ejection fraction > 30% (HR 0.485; 95% CI [0.290-0.813]; P = 0.006) were independently associated with lower rates of recurrence or disease-related death. Other procedural parameters were similar in both groups. In conclusion, UHD mapping during VT ablation was associated with fewer VT recurrences or disease-related deaths during long-term follow-up in comparison to conventional point-by-point mapping. Complication rates and other procedural parameters were similar in both groups.

Figure 1

Single center sequential comparison study. The figure depicts the design of the present study. The acute and long-term outcome of patients whose ablation of ventricular tachycardia (VT) was guided by ultra-high-density mapping (UHD group) was compared to patients with conventional point-by-point 3D-mapping (conventional mapping group). Ultra-high-density mapping was established at the study center in 2015. Sixty-one consecutive patients with UHD mapping were included into the study. Patient selection started after a six-months run-in period after introduction of the system to avoid a learning-curve-effect. The patients’ outcome was compared to 61 consecutive patients that had a VT ablation guided by conventional 3D-mapping between 2013 and 2015, before introduction of UHD mapping.

Figure 2

Substrate maps of the left ventricle. (A) Ultra-high-density map. (A) shows an ultra-high-density map of the left ventricle, created with a basket catheter (34,692 points). (B) Conventional point-by-point map. (B) shows a conventional map of the left ventricle, created by point-by-point mapping with a single tip catheter (889 points). Both maps are shown in the projection right anterior oblique. The colour scale symbolizes the myocardial voltage, the range is displayed in the right upper corner. The large blue and yellow balls in B mark abnormal electrograms. Bi indicates bipolar; mV, millivolt; RAO, right anterior oblique.

Figure 3

Lower rates of recurrence or disease-related death after catheter ablation of ventricular tachycardia guided by ultra-high-density mapping versus conventional point-by-point 3D-mapping. Cumulative incidence of recurrence or disease-related death in the first 24 months after ablation are displayed. Patients with ablation guided by ultra-high-density mapping had a lower recurrence or disease-related death rate at 12-/24-months of followup (see also Table 2B). Patients with ultra-high-density mapping are depicted in red, patients with conventional point-by-point 3D-mapping in cyan. Steps represent a first recurrence or disease-related death. Non-disease-related death (not displayed) was considered as competing risk.

Figure 4

Ultra-high-density mapping and left ventricular ejection fraction > 30% are independently associated with improved long-term outcome. A Forest plot of a multivariable cause-specific Cox proportional hazards model for time to recurrence or disease-related death is displayed. Values on the right side of the line represent a higher likelihood and values on the left a lower likelihood of a first recurrence or disease-related death. Results are presented as hazard ratio with 95% confidence interval. P < 0.05 is considered significant. The parameter “age” represents the effect of a 10-year increase in patient age on the likelihood of recurrence or disease-related death. The model adjusts for mapping technique, age, sex, body mass index (BMI), type of cardiomyopathy, chronic kidney disease, left ventricular ejection fraction (LV-EF) and antiarrhythmic drug therapy (AAD) before ablation. AAD indicates antiarrhythmic drugs; BMI, body mass index; CI, confidence interval; HR, hazard ratio; LV-EF, left ventricular ejection fraction; nICMP, non-ischemic cardiomyopathy.