Therapeutic benefits of distal ventricular pacing in mid-cavity obstructive hypertrophic cardiomyopathy

INTRODUCTION Hypertrophic cardiomyopathy (HCM) patients with left ventricular (LV) mid-cavity obstruction (LVMCO) often experience severe drug-refractory symptoms thought to be related to intraventricular obstruction. We tested whether ventricular pacing, guided by invasive haemodynamic assessment, reduced LVMCO and improved refractory symptoms. METHODS Between December 2008 and December 2017, 16 HCM patients with severe refractory symptoms and LVMCO underwent device implantation with haemodynamic pacing study to assess the effect on invasively defined LVMCO gradients. The effect on the gradient of atrioventricular (AV) synchronous pacing from sites including right ventricular (RV) apex and middle cardiac vein (MCV) was retrospectively assessed. RESULTS Invasive haemodynamic data were available in 14 of 16 patients. Mean pre-treatment intracavitary gradient was 77 ± 22 mmHg (in sinus rhythm) versus 21 ± 21 mmHg during pacing from optimal ventricular site (95% CI: -70.86 to -40.57, p < 0.0001). Optimal pacing site was distal MCV in 12/16 (86%), RV apex in 1/16 and via epicardial LV lead in 1/16. Pre-pacing Doppler-derived gradients were significantly higher than at follow-up (47 ± 15 versus 24 ± 16 mmHg, 95% CI: -37.19 to -13.73, p < 0.001). Median baseline NYHA class was 3, which had improved by ⩾1 NYHA class in 13 of 16 patients at 1-year post-procedure (p < 0.001). The mean follow-up duration was 4.6 ± 2.7 years with the following outcomes: 8/16 (50%) had continued symptomatic improvement, 4/16 had symptomatic decline and 4/16 died. Contributors to symptomatic decline included chronic atrial fibrillation (AF) (n = 5), phrenic nerve stimulation (n = 3) and ventricular ectopy (n = 1). CONCLUSION In drug-refractory symptomatic LVMCO, distal ventricular pacing can reduce intracavitary obstruction and may provide long-term symptomatic relief in patients with limited treatment options. A haemodynamic pacing study is an effective strategy for identifying optimal pacing site and configuration

Atrioventricular node ablation is an effective management strategy for atrial fibrillation in patients with hypertrophic cardiomyopathy

BACKGROUND: Atrial fibrillation (AF) is common in hypertrophic cardiomyopathy (HCM) patients and can be challenging to manage. Atrioventricular node (AVN) ablation may be an effective management strategy for AF in these patients. OBJECTIVE: Assess the efficacy of AVN ablation in HCM patients who have failed medical therapy and/or catheter ablation for AF. METHODS: Multi-centre study with retrospective analysis of a prospectively collated HCM registry. AVN ablation patients were identified. Baseline characteristics, device and procedural indication were collected. Symptoms defined by NYHA and EHRA classification and echocardiographic findings during follow-up were assessed. RESULTS: Fifty-nine patients were included. Indications for AVN ablation were: 6 (10.2%) inappropriate ICD shock, 35 (59.3%) ineffective rate control and 18 (30.5%) to regularize rhythm to improve symptoms. During post-AVN ablation follow-up of (79.4±61.1 months), left ventricular ejection fraction (LVEF) remained stable (pre-LVEF 48.9±12.4%, post-LVEF 49.8±10.9%, p=0.68) even in those without a CRT device (pre-LVEF 54.3±8.0% vs post-LVEF 53.8±8.0%=0.65). Forty-nine (83.1%) patients reported an improvement in symptoms regardless of AF type (17/21, 81.0% paroxysmal vs. 32/38, 84.2% persistent AF; p=1.00), presence of baseline LV impairment (22/26, 84.6% LVEF≤50% vs. 27/33, 81.8% LVEF≥50%; p=1.00) or CRT device (27/32, 84.4% CRT vs. 22/27, 81.5% no CRT; p=1.0). Symptoms improved in 16 (89%) patients who underwent AVN ablation to regularize rhythm. CONCLUSION: AVN ablation improved symptoms without impacting LV function in a majority of the patients. AVN ablation is suggestive to be an effective and safe management approach for AF in HCM and should be further evaluated in larger prospective studies