Clinical characteristics of multifocal premature ventricular complexes originating from the basal septal region of the left ventricle: Anatomy, mapping, and ablation.

BACKGROUND

Clinical recognition of multifocal premature ventricular complexes (PVCs) poses diagnostic and therapeutic challenges. Despite their morphological diversity, these arrhythmias may originate from a confined anatomical region, allowing a systematic mapping and ablation strategy.

OBJECTIVE

To describe clinical characteristics and propose a stepwise approach to mapping and ablation of multifocal PVCs originating from the basal septal left ventricular (LV) ostium.

METHODS

Patients with multifocal septal PVCs who underwent coronary venous mapping were included. Ablation targeted the basal LV septum from the anterolateral LV ostium to the posterior LV process.

RESULTS

Twenty-four patients (mean age, 64.5 ± 9.2 years; 92% male) were included. Baseline electrocardiogram showed PR prolongation of >200 ms in 50%, QRS of >100 ms in 75%, absent septal R waves in 63%, and QRS fractionation in inferior leads in 38%. LV ejection fraction was preserved or mildly reduced (median, 45%). Cardiac magnetic resonance showed delayed gadolinium enhancement in 71%, and intracardiac echocardiography revealed septal abnormalities in 83%. Intramural coronary venous mapping was feasible in 75%, revealing fractionated electrograms; intramural activation preceded endocardial activation by 10 ms (P < .01). Thirteen patients (54%) received an implantable cardioverter-defibrillator. PVC burden decreased from 18.7% to 2.8% (P < .01), with ≥80% reduction in 83%. During 1.7 years of follow-up, 4 patients (31%) received appropriate therapies.

CONCLUSION

Multifocal septal PVCs are consistently associated with abnormalities on electrocardiogram, cardiac magnetic resonance and/or intramural septal electrograms. A stepwise ablation approach substantially reduces PVC burden, although damage to the conduction system remains clinically relevant. The risk of malignant ventricular arrhythmias remains high despite preserved or mildly reduced LV ejection fraction.