• Arrhythmias
• Cardiology Clinical Trials
• Interventional Techniques & Devices

• Cardiology & Cardiovascular Medicine

Andrea Natale, MD, Texas Cardiac Arrhythmia Institute, Austin, Texas, USA, presented the 12-month findings from the Ablation of Symptomatic Paroxysmal Atrial Fibrillation Using Novel Contact Force Catheter trial [SMART-AF]. The study met its safety and effectiveness endpoints with no unanticipated device-related adverse events (AEs), and with 72% of the ablated patients free from atrial fibrillation (AF) recurrence. Furthermore, increased freedom from arrhythmia was correlated with increased percentage of time within physician-targeted contact force range.

The purpose of this study was to evaluate the safety and effectiveness of a new deflectable and irrigated tip catheter in treating drug-refractory symptomatic paroxysmal AF. The catheters have a sensor that measures the direct contact force between the heart tissue and the catheter tip. The devices were used with a navigation system that displayed integrated contact force and direction data. The ablation protocol included circumferential pulmonary vein isolation with confirmation of entrance block This prospective, multicenter, single-arm study included 172 drug-refractory AF patients (aged ≥18 years) with left ventricular ejection fractions ≥40%.

The primary efficacy endpoint was freedom from documented symptomatic AF/atrial tachycardia (AT)/atrial flutter. Acute procedural failure, the introduction of a new antiarrhythmic drug for AF during the effectiveness period, repeat ablation beyond the 90-day blanking period, and >2 repeat ablation procedures in the blanking period were all considered efficacy failures. The primary safety endpoint was the incidence of early-onset primary AEs within 7 days of an AF ablation procedure. Assessments were made at 1, 3, 6, 9, and 12-month visits.

The majority of patients were male (72.1%) and Caucasian (96%), with a mean ±SD age of 58.8±11.0 years; 59.3% were hypertensive; mean ±SD AF duration was 5.4±5.1 years, and mean ±SD left atrial diameter was 38.6±6.1 mm.

The primary safety goal was met: the incidence of early-onset primary AEs was 9.9% (upper limit of confidence was 15.6%). There were no unanticipated device-related AEs: no deaths, and no incidence of stroke, transient ischemic attack myocardial infarction, phrenic nerve palsy, atrio-esophageal fistula, thromboembolism, or pulmonary vein stenosis. Contact force had no effect on early primary AEs. There were four cases of cardiac tamponade and three vascular access complications.

Acute success was achieved in all subjects in the effectiveness cohort. At the end of the 12-month follow-up, 72% of patients were free from AF/AT/atrial flutter recurrences and 69% were deemed protocol-adjudicated successes (p<0.001).

Investigators selected their own contact force working range; 67% used a range of 5–40g. There was a significantly higher (15%; log-rank p value 0.03) success rate for primary effectiveness when contact force was within ≥80% of the investigator-selected range.

Post ablation, there were clinically meaningful improvements (≥3 points) in physical and mental quality of life measures; symptom frequency and severity scores also decreased.

The catheter has been approved by the FDA for use in the United States.

• © 2013 MD Conference Express®