Impact of real-time contact force and impedance measurement in pulmonary vein isolation procedures for treatment of atrial fibrillation.

BACKGROUND: Pulmonary vein isolation (PVI) is an established procedure to treat atrial fibrillation (AF). New techniques are necessary to improve procedural parameters like shortening of procedure duration. Real-time contact force (CF) catheters are new tools aiming to improve PVI by optimizing electrode-tissue contact and generating more effective lesions. Objective of this study was to investigate the influence on procedural parameters and clinical outcome by using a CF catheter for PVI. METHODS: PVI was performed on 67 consecutive patients using a CF catheter (n = 32) or a standard ablation catheter (SAC, n = 35). Study endpoints included number of energy applications, impedance drop, fluoroscopy time, and left atrial (LA) procedure time and freedom from AF after 6 and 12 months. RESULTS: Procedural endpoint was reached in all patients with a similar clinical outcome (freedom from AF) in both groups 6 months (62.9 vs. 62.5%) and 12 months post PVI (59.4 vs. 62.9% in CF vs. SAC group, respectively). However, CF-guided ablation resulted in a greater fall of impedance (6.58 ± 0.33 vs. 9.09 ± 0.53 Ω, *** p < 0.001), lower number of energy applications (44.20 ± 3.67 vs. 34.06 ± 3.11, * p < 0.05), reduction of LA procedure time (95.52 ± 7.35 vs. 78.08 ± 7.23* min) and a significant reduction of fluoroscopy time (51.4 ± 3.3 vs. 33.0 ± 2.7*** min). In addition, a detailed analysis showed a significant correlation between quantitative impedance drop and amount of CF applied, suggesting more efficient lesion creation by CF-guided ablation. CONCLUSION: Use of CF catheters in PVI has a beneficial effect on procedural parameters, probably by improving efficacy of transmural lesion formation.

The amount of viable and dyssynchronous myocardium is associated with response to cardiac resynchronization therapy: initial clinical results using multiparametric ECG-gated [18F]FDG PET.

PURPOSE: There is still a significant amount of patients who do not sufficiently respond to cardiac resynchronization therapy (CRT). Previous studies demonstrated that the amount of dyssynchronous myocardium was predictive of response to CRT. Otherwise, non-response is frequently associated with high amounts of scar tissue. The combination of these parameters might yield a more accurate prediction of response. We hypothesized that the probability of a CRT response increases with the presence of high amounts of "viable and dyssynchronous" myocardium. METHODS: A total of 19 patients (17 male, 61 ± 10 years) underwent ECG-gated [(18)F]fluorodeoxyglucose (FDG) myocardial positron emission tomography (PET) before CRT device implantation and were followed for 6 months. Response to CRT was defined as clinical improvement of at least one New York Heart Association (NYHA) class in combination with left ventricular (LV) ejection fraction (EF) improvement of >5%. Twelve responders (71%) and seven non-responders (29%) were identified. For each patient bullseye maps of FDG uptake and phase analysis were calculated (QPS/QGS 2012, Cedars-Sinai, Los Angeles, CA, USA) and fused. Amounts of myocardium representing "viable and synchronous", "scar and synchronous", viable and dyssynchronous or "scar and dyssynchronous" myocardium were quantified by planimetric measurements of the fused bullseye maps. RESULTS: Responders by definition showed significant decrease in NYHA class and significant increase of LVEF. Furthermore, a significantly higher amount of viable and dyssynchronous myocardium was found as compared to non-responders (21 ± 13% vs 6 ± 5%; p < 0.05). CONCLUSION: Combined assessment of myocardial viability and LV dyssynchrony is feasible using multiparametric [(18)F]FDG PET and could improve conventional response prediction criteria for CRT.