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.

Characterisation and Comparison of Acute Haemodynamic, Cardiac Biochemical and Hormonal Response to Different Ventricular Pacing Sites in the Normal Heart.

BACKGROUND: Acute cardiac response to right ventricular pacing is unknown. We aimed to assess the acute haemodynamic, biochemical and hormonal response to asynchronous right ventricular pacing and investigate whether there is a difference between an apical and outflow tract site. METHODS: In 21 patients with normal cardiac function, haemodynamics, brain natriuretic peptide and high sensitive troponin T were measured in response to 10minutes of pacing at each site in a randomised crossover fashion and compared. RESULTS: Pacing both sites there were significant increases in pulmonary capillary wedge pressures (p<0.001) and QRS width (p< 0.01). In comparison to baseline, apical pacing demonstrated significant (p<0.05) increases in arterial peptide and troponin levels and venous peptide levels. Outflow tract pacing compared to baseline demonstrated significant (p<0.05) increases in arterial peptide and venous, arterial and coronary sinus troponin. There were no significant differences in responses between sites. CONCLUSION: Asynchronous right ventricular pacing demonstrated significant increases in filling pressures, cardiac hormonal and biochemical response above baseline with very short durations of pacing (10minutes). There was no difference in response between sites. These findings imply that even very short periods of right ventricular based pacing are potentially deleterious.