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.