Non-compliant Left Atrium Due to Scarring From Atrial Fibrillation Ablation Leads to Discordance of PAWP-LVEDP and Severe Post-Capillary Pulmonary Hypertension

Abstract

Introduction Atrial fibrillation (AF) is one etiology of WHO group II post-capillary pulmonary hypertension (PH). Higher left atrial pressure, estimated as pulmonary artery wedge pressure (PAWP) out of proportion to left ventricular end-diastolic pressure (LVEDP), has been reported in AF. However, the impact of atrial scarring associated with AF ablation (ABL) on these pressure differences remains unclear. Hypothesis Extensive AF ABL leads to scarring of the left atrial wall, decreasing atrial compliance, which leads to elevated left atrial pressure in the presence of a lower LVEDP creating a PAWP-LVEDP gradient. Methods We selected all patients who were diagnosed with PH (n=4,945) between 2009 and 2019 at the University of Wisconsin-Madison who underwent simultaneous right and left heart catheterization and had an EP procedure (n=27), after excluding patients with significant mitral valve disease and amyloid. We then divided them into 3 groups: group 1 (AF-ABL) n=5, group 2 (AF) n=16, group 3 (no AF) n=6. Results The PAWP-LVEDP gradient among three groups was (AF-ABL vs AF vs No AF): +6.8±3.42 vs -0.2±4.4 vs -1.8±4.0 mm Hg (Figure). Among the overall cohort, we further analyzed the patients with PAWP-LVEDP gradient >2 (discordant) vs ≤2 (concordant). PAWP-LVEDP gradient between the discordant group (n=12) vs the concordant group (n=15) was +5.0±2.7 vs -2.7±3.6*. Among the discordant group, 5 had AF ABL and 6 had AF. Among the concordant group, 5 had no AF, 10 had AF and no patients had AF ABL. The characteristics between discordant (DIS) vs concordant (CON) groups were: Age 68.2 ± 10 vs 67.0 ± 19.3, BMI 33.6 ± 4.55 vs 30.8 ± 11.2, diabetes 33% vs 47%, hypertension 75% vs 67%, OSA 91% (11/12) vs 40% (6/15)*, systolic pulmonary artery pressure (PAP) 55±19 vs 41±11*, mean PAP 37±12 vs 29±8*, PAWP 20±6 vs 18±7*, LVEDP 15±6 vs 20±7*. All patients who underwent ablation had persistent type AF and had extensive ablation beyond PVI (4 of 5 with PVI). Among the 16 patients with AF (without ABL - 6 in DIS, 10 in CON groups), 8 had paroxysmal (3 in DIS, 5 in CON) and 8 had persistent AF (3 in DIS, 5 in CON). While age, BMI, HTN and DM were similar among DIS vs CON groups, the incidence of OSA was higher. However, given the patients with elevated PAWP-LVEDP gradient have worse PH, we suspect they were more likely to be tested for OSA (referral bias). Conclusion AF ablation is associated with an increased PAWP-LVEDP gradient likely from atrial scarring and non-compliance of the left atrium. Patients with elevated PAWP-LVEDP gradient have worse pulmonary hypertension and are more likely to be diagnosed with OSA.