Ablation of typical atrial flutter using mini electrode measurements for maximum voltage-guided ablation: A randomized, controlled trial.

BACKGROUND: Novel ablation catheters with mini electrode (ME) sensing have become available but their utility is unclear. We investigated whether ablation of the cavotricuspid isthmus (CTI) for atrial flutter (AFL) would be improved using ME signals. METHODS: Sixty-one patients (76% male, 63 ± 10 years) with CTI-dependent AFL underwent ablation using a maximum voltage-guided approach, randomized to either standard 8 mm non-irrigated catheter with bipolar signals or IntellaTip MiFi catheter using ME signals alone. RESULTS: Acute bidirectional block was achieved in 97%. Mean follow-up was 16.7 ± 10 months. The median number of ablation lesions was 13 in both groups (range 3-62 vs. 1-43, p = .85). No significant differences were observed in AFL recurrences (17% vs. 11%, p = .7), median procedure durations (97 min [interquartile range (IQR), 71-121] vs. 87 min [IQR, 72-107], p = .55) or fluoroscopy times (31 min [IQR, 21-52] vs. 38 min [IQR, 25-70], p = .56). Amplitudes of ME signals were on average 160% greater than blinded bipolar signals. In 23.7% of lesions where bipolar signals were difficult to interpret, 13.6% showed a clear ME signal. CONCLUSIONS: There was no difference in the effectiveness of CTI ablation guided by ME signals, compared with using bipolar signals from a standard 8 mm ablation catheter. While ME signal amplitudes were larger and sometimes present when the bipolar signal was unclear, this did not improve procedural characteristics or outcomes. The results suggest future research should focus on lesion integrity rather than signal sensing.

Characteristics of Cavotricuspid Isthmus Ablation for Atrial Flutter Guided by Novel Parameters Using a Contact Force Catheter.

INTRODUCTION: This study sought to investigate specific contact force (CF) parameters to guide cavotricuspid isthmus (CTI) ablation and compare the outcome with a historical control cohort. METHODS AND RESULTS: Patients (30) undergoing CTI ablation were enrolled prospectively in the Study cohort and compared with a retrospective Control cohort of 30 patients. Ablation in the Study cohort was performed using CF parameters >10 g and <40 g and a Force Time Integral (FTI) of 800 ± 10 g. The Control cohort underwent traditionally guided CTI ablation. Traditional parameters (electrogram and impedance change) were assessed in both cohorts. All ablations regardless of achieving targets were included in data analysis. Bidirectional CTI block was achieved in all of the Study and 27 of the Control cohort. Atrial flutter recurred in 3 (10%) patients (follow-up 564 ± 212 days) in the study cohort and in 3 (10%) patients (follow-up 804 ± 540 days) in the Control cohort. There were no major complications in either cohort. Traditional parameters correlated poorly with CF parameters. In the Study cohort, flutter recurrence was associated with significantly lower FTI and ablation duration, but was not associated with total average CF. CONCLUSION: CTI ablation can be safely performed using CF parameters guiding ablation, with similar long-term results to a historical ablation control group. Potentially CF parameters may provide adjunctive information to enable a more efficient CTI ablation. Further research is required to confirm this.

Radiation risk reduction in cardiac electrophysiology through use of a gridless imaging technique.

AIMS: It has been previously demonstrated that use of appropriate frame rates coupled with minimal use of high-dose digital acquisition can limit radiation risk to patients undergoing diagnostic and therapeutic electrophysiology (EP). Imaging without the anti-scatter grid has been proposed as a means of achieving further radiation reduction. We evaluate application of a gridless imaging technique to deliver further reductions in radiation risk to both patients and personnel. METHODS AND RESULTS: Radiation and clinical data for EP procedures performed for 16 months from March 2012 were monitored. The period was divided into three phases: Phase 1 (March 2012-June 2012) provided a performance baseline (radiation output modelling and procedural risk adjustment calibration), Phase 2 (July 2012-September 2012) confirmation of performance with the grid, and Phase 3 (September 2012-June 2013) gridless imaging period. Statistical process control (SPC) charts were used to monitor for changes in radiation use and clinical outcomes (procedural success). Imaging without the grid halved the levels of radiation delivered in undertaking EP procedures. Although there was a perceptible impact on image quality with the grid removed. Review of the SPC chart monitoring procedural outcomes did not identify any discernable adverse impact on success rates. Selected use of the gridless technique is recommended with re-introduction of the grid in larger patients or during aspects of the procedure where image quality is important (e.g. transeptal punctures). CONCLUSION: Use of a gridless imaging technique can contribute to a significant reduction in radiation risk to both patients and operators during cardiac EP procedures.

A comparison of right ventricular non-apical defibrillator lead position with traditional right ventricular apical position: a single centre experience.

BACKGROUND: Implantable cardioverter defibrillator (ICD) leads have traditionally been placed at the right ventricular apex (RVA). An important minority of patients with an ICD may develop a future requirement for bradycardia support. Pacing from the RVA may be detrimental, promoting heart failure and mortality. Increasingly non-apical right ventricular (RVNA) lead positions have been suggested as an alternative pacing site. METHODS: A retrospective review of 512 patients who received an ICD at our institution between 1999 and 2011 was conducted. A comparison of lead performance characteristics was performed between RVNA sites and those at RVA. Data were collated from chart review and the pacing database. RESULTS: The mean follow-up period in the RVNA cohort was 40.4±25.9 months and in the RVA cohort it was 38±31.8 months (p=0.43). The RVNA cohort consisted of 144 leads and 368 leads in the RVA cohort. The groups had similar baseline clinical characteristics. No significant difference was detected in the proportion of patients receiving an appropriate ICD defibrillation (RVNA 10.4% vs. RVA 16.8%; p=0.07), inappropriate defibrillation (RVNA 7.6% vs. RVA 7.6%; p=0.99) or an unsuccessful defibrillation (RVNA 0% vs. RVA 1.7%; p=0.12). There was also no significant difference in the proportion of patients receiving successful anti-tachycardia pacing (ATP) (RVNA 13.2% vs. RVA 17.4%; p=0.49) or failed ATP (RVNA 2.7% vs. RVA 4.1%; p=0.25). There was no significant difference in lead impedance (p=0.99), sensing (p=0.59) and pacing threshold (p=0.34). CONCLUSION: In this large retrospective study, RVNA ICD lead had similar stability and therapy efficacy compared to the traditional RVA position. This potentially has important implications for the suitability of RVNA as an alternative site for ICD leads.