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OBJECTIVE:
The minimally invasive, epicardial off-pump ablation has been reported as a feasible option in selected patients with drug-resistant lone atrial fibrillation (AF). It is important to stratify the patients on the basis of their risk of recurrence. We addressed whether increased plasma Homocysteine is associated with recurrent AF after successful minimally invasive epicardial ablation, and whether it could be useful as a preoperative predictor of outcome.
METHODS: In the setting of a prospective observational study, we enrolled patients subjected to minimally invasive epicardial ablation of lone AF who leaved the hospital in stable sinus rhythm. Blood samples were obtained on day before surgery and at the six months follow-up visit. Plasma Homocysteine levels were determined in both samples and expressed as µmol/L. The recurrence of AF was demonstrated by scheduled 24-hours ECG monitoring.
RESULTS: A total of 104 patients were enrolled. The rate of freedom from AF was 88.5% (92 patients) at an average 17-months follow-up. In patients with at the least one episode of recurrent AF, the average preoperative Homocysteine was 16.9 µmol/L vs. 13.1 µmol/L in patients without recurrence (p=0.032). Patients having preoperative persisting-type AF had average preoperative Homocysteine=15.4 µmol/L vs. 12.1 µmol/L in patients with paroxysmal-type AF (p=0.002). Patients having with preoperative enlarged left atrium (defined as left atrial size ≥22 mm/m²) displayed higher average preoperative Homocysteine levels (p<0.01). Similar results were obtained with the Homocysteine levels measured at 6 months. Cox proportional hazards regression evidenced increased preoperative and 6-months homocysteine levels (continuous variable) as an independent predictor of recurrent AF. The cutoff value of 15.1 µmol/L for preoperative Homocysteine level displayed the best diagnostic performance in predicting the recurrence of AF during the follow-up (area under the Receiver Operating Characteristic curve = 0.89).
CONCLUSIONS: Higher preoperative Homocysteine levels are significantly associated with the recurrence of lone AF after minimally invasive epicardial ablation. This factor should be weighted in conjunction with other predictors of recurrence (persisting type of AF, advanced left atrial remodeling) in the establishment of surgical indication for lone AF.