Ventricular arrhythmias from the mitral annulus: patient characteristics, electrophysiological findings, ablation, and prognosis.

Background: Symptomatic, premature ventricular contractions (PVCs) frequently originate in the right ventricular outflow tract, less frequently in the left ventricular outflow tract, aortic root, or mitral annulus (MA). Little is known about the patient population presenting with MA PVC and/or ventricular tachycardia (VT).

Objective: To characterize the subgroup of ventricular arrhythmias arising from the MA.

Methods: Among 404 consecutive patients who presented for catheter ablation of idiopathic PVC/VT over a period of 9 years, patients who were found to have an ablation site at the MA were analyzed for clinical and electrophysiological parameters.

Results: Twenty-two (5%) patients (mean age 45 ± 18 years; range 16-76 years; 14 [64%] men) had PVC/VT arising from the MA. History of PVC ranged from 2 days in a case with suspected focal myocarditis to 19 years. No patient had severely depressed left ventricular function or significant heart disease, which was determined by echocardiogram, magnetic resonance imaging, and/or coronary angiogram. Sites of origin were distributed around the MA with no preferential area. Ablation was successful in 13 of 16 (81%) patients. One 28-year-old female patient with normal magnetic resonance imaging and no structural heart disease died suddenly 3 months after ablation.

Conclusions: Ventricular arrhythmias from the MA represent a rare subgroup of idiopathic PVC/VT. They appear to occur at any age and do not indicate underlying structural heart disease. Catheter ablation has a success rate comparable to that of outflow tract tachycardia. Prognosis remains unclear.