Discussion
In this study of catheter ablation for symptomatic VT and PVC in patients with prior MVS, we demonstrated the following: 1. Catheter ablation is an effective treatment modality with reasonable long term outcomes, 2. The clinical arrhythmia, be it VT or PVC, was frequently not related to the perimitral region, 3. Most patients presented late after MVS with an average time latency of 4.0 (IQR 0.3, 12.1) and 3.4 (QR 0.6, 8.0) years for VT and PVCs onset, respectively and 4. Catheter ablation is safe in this patient population, with no instances of catheter entrapment or mitral valve malfunction.
Following cardiac valve surgery, atrial arrhythmias are much more frequently encountered than VAs.19-21 As such, characteristics of VA and the associated ablation in this population have not been well delineated. Our methods did not permit us to establish the incidence of VA following MVS. However, there is some limited data with respect to acute postoperative VA incidence. A large study for post-cardiac surgery outcomes included 813 patients with valve surgery. Of these, only 6 (0.74%) patients developed sustained VT post valve surgery.22. Though this study included 749 patients with MVS, the incidence of VT was reported after valve surgery in general. Another study reported that the incidence of VT was 8% in patients with mitral valve replacement compared to 21% with aortic valve replacement.23 Though these studies evaluated acute incidence, VA can present years following surgical intervention, akin to postoperative atrial flutter and post myocardial infarction ventricular arrhythmias.10 Indeed, variation in VA onset following cardiac surgery might be related to the difference in VA mechanisms, for example early-onset being associated with neurohormonal imbalance, automaticity with later onset being more likely to be associated with reentry.