915ATP efficacy on terminating ventricular tachycardia by device type, indication, and ventricular median cycle length

Funding Acknowledgements

Medtronic

OnBehalf

PainFree SST

Background

Anti-tachycardia Pacing (ATP) is an established therapy that terminates VT without the need for painful ICD shocks. Here we use the data from PainFree SST clinical trial to evaluate the ATP success rate by device type, indication and MCL. 

Methods

Spontaneous episodes that were detected by ICD or CRT-D devices in the VT, fast VT and VF zones were included in the analysis. Episodes successfully terminated by ATP were deemed as having ATP success. Using the GEE method, ATP success rate and its 95% CI were calculated for device types, indications and ventricular MCL. 

Results

Of the 2770 enrolled patients (79% male, average age 65 years), 1699 (61%) were implanted with an ICD and 1071 (39%) with a CRT-D system; 1917 (69%) were reported as primary prevention and 847 (31%) were secondary prevention patients. For all MVT episodes, the ATP success rate was similar between ICD and CRT-D devices (82.3% vs 80.3%, p = 0.74). Patients with secondary prevention had a higher ATP success rate compared to those with primary prevention but the difference was not statistically significant (84.4% vs 76.8%, p = 0.16). Regardless of device type and indication, ATP success rate was significantly higher in the slower VTs (MCL ≥ 320 ms) compared to the faster VTs (MCL ≥ 240 to < 320 ms) (89.2% vs 73.7%, p < 0.0001). 

Conclusion

We found that ATP had a greater than 80% rate of success for terminating ventricular tachycardias overall. Slower VTs was significantly associated with a higher ATP success rate regardless of device type and indication compared to faster VTs. For faster VTs with a MCL ≥ 240 to < 320 ms, the ATP success rate was still successful at terminating VT more than 70% of the time.

Table 1. ATP Success Rates - No. of Enrolled Subjects (% of total) No. of Episodes Analyzed for ATP Success (No. of Subjects) GEE-estimated ATP Success Rate (95% CI) P-value* Overall 2770 (100%) 2277 (376) 81.5% (78.4%, 84.2%) - Device Type - - - 0.7440 ICD 1699 (61.3%) 1484 (229) 82.3% (78.3%, 85.6%) - CRT-D 1071 (38.7%) 793 (147) 80.3% (75.0%, 84.6%) - Indication - - - 0.1609 Primary Prevention 1917 (69.2%) 631 (160) 76.8% (71.2%, 81.6%) - Secondary Prevention 847 (30.6%) 1615 (212) 84.4% (80.7%, 87.6%) - Median Cycle Length - - - <0.0001 (>/=) 240 ms and < 320 ms - 861 (257) 73.7% (69.2%, 77.7%) - (>/=) 320 ms - 1416 (209) 89.2% (85.7%, 91.9%) - * Per a GEE main effect model for all episodes where device type, indication and median cycle length were considered.

Long-term survival and complications in patients with malignant ventricular tachyarrhythmias: treatment with a nonthoracotomy implantable cardioverter defibrillator with or without a subcutaneous patch

The Endotak lead system and ICD has been used to treat patients with malignant ventricular arrhythmias. We analyzed the clinical characteristics of 1,053 patients who underwent implantation of the Endotak lead system with or without a subcutaneous patch. Group A consisted of 567 patients receiving the Endotak lead with a subcutaneous patch; group B consisted of 486 patients receiving the Endotak lead alone. The 2-year survivals from sudden death, cardiac death, and total death in groups A and B were 97.6%/98.2% (P = 0.38), 88.6%/92.7% (P = 0.09), and 84.7%/86.8% (P = 0.06), respectively. Minimum tested effective defibrillation energy at implantation was 17.2 +/- 5.2 J for group A and 15.8 +/- 5.1 J for group B (P < 0.01). The operative mortality was 1.8% in group A and 0.6% in group B (P = 0.09). The incidence of lead dislodgment, malfunction, and infection was 6.7% for group A and 3.5% for group B (P < 0.01). Sudden death survival was excellent in both groups with less lead complications in group B. The Endotak lead alone may be the preferred choice of lead configuration in those patients who have adequate defibrillation thresholds at implant.