Initial experience of temperature-controlled irrigated radiofrequency ablation for ischaemic cardiomyopathy ventricular tachycardia ablation

Abstract

Background: The DiamondTemp ablation (DTA) catheter system delivers high power, open-irrigated, temperature-controlled radiofrequency (RF) ablation. This novel ablation system has not been previously used for ventricular tachycardia (VT) ablation.

Objective: Feasibility of using the DTA catheter system for VT ablation in ischaemic cardiomyopathy (ICM) patients.

Method: Ten ICM patients with optimal anti-arrhythmic drug therapy and implantable cardiac defibrillators (ICD) were recruited. VT inducibility testing was performed at the end of the procedure. ICD data for device detected VT episodes and device treated VT episodes were collected for 6-months pre- and post-ablation.

Results: Substrate analysis demonstrated reductions in the borderzone area of 4.4 cm² (p = 0.026) and late potential area of 3.5 cm² (p = 0.0449) post-ablation, with reductions in the mean bipolar and unipolar voltages of the ablation target areas (0.14 mV (p = 0.0007); 0.59 mV (p = 0.0072) respectively). Complete procedural success was achieved in 9 procedures. Post-ablation VT inducibility testing was not performed in 1 procedure due to a steam pop complication resulting in pericardial tamponade requiring drainage. Mean follow-up of 214 ± 33 days revealed an 88% reduction in total VT episodes (n = 266 median 16 [IQR 3-57] to n = 33 median 0; p = 0.0164) and 77% reduction in ICD therapies (n = 128 median 5 [IQR 2-15] to n = 30 median 0; p = 0.0181).

Conclusion: The DTA system resulted in adequate lesion characteristics with effective substrate modification, acute procedural success and improved outcomes at intermediate-term follow-up. Randomised controlled trials are required to compare the performance of the DTA system against conventional ablation catheters.

Keywords: Feasibility; Ischaemic cardiomyopathy; Temperature-controlled irrigated radiofrequency ablation; Ventricular tachycardia.

Fig. 1

The DiamondTemp catheter. The DiamondTemp ablation (DTA) (Medtronic, Inc., Minneapolis, Minnesota) catheter tip consists of a 4.1 mm distal electrode comprised of platinum:iridium (Pt:Ir), chemical vapour deposit (CVD) diamond network, 6 external thermocouples (TCs) and 6 saline irrigation ports. The CVD network allows thermal energy transfer that is 200–400 times faster than achieved with other catheter systems. The catheter provides temperature control to maintain 60 °C at the tissue surface with real-time power modulation, as shown in the representative graphs of power, temperature and impedance change over the course of a single 60 s ablation lesion

Fig. 2

Representative case. Substrate and LP maps are shown in a representative case pre- and post-ablation, using standard LV bipolar voltage criteria, with the ATA highlighted with the dashed white line. Post-ablation, the BZA has been effectively reduced from 7.5 to 3.2 cm² with a corresponding increase in the DSA. The pre-ablation LPA (5.8 cm²) has been completely eliminated. The mean bipolar voltage of the ATA pre-ablation was 0.43 mV and effectively reduced to 0.36 mV post-ablation. b Electrogram amplitude attenuation of the bipolar LP signal from the DTA distal high-resolution electrode is shown (LP = late potential; ATA = ablation target area; BZA = borderzone area; DSA = dense scar area)

Fig. 3

Follow-up data. Histograms showing individual a device detected VT episodes and b device treated VT episodes within the 6 months pre-ablation period compared to the minimum 6 months post-ablation follow-up. Pre-ablation device detected VT episodes n = 266; median 16 [IQR 3–57]. Post-ablation device detected VT episodes n = 33; median 0 (p = 0.0164). Pre-ablation device treated VT episodes n = 128 median 5 [IQR 2–15]. Post-ablation device treated VT episodes n = 30; median 0 (p = 0.0181). Values are mean ± SD.

Fig. 4

Temperature versus Impedance. Scatter plot of all 518 ablation lesions demonstrating a poor correlation between maximum temperature and impedance decrease (r coefficient = 0.36; p value = 0.01). Lesion X identifies ablation lesion resulting in steam pop and pericardial tamponade