Terpstra, M M

Abstract Background Left atrial appendage (LAA) closure or amputation is commonly performed in atrial fibrillation (AF) patients undergoing cardiac surgery to reduce stroke risk. It has been shown that LAA closure or amputation results in persistent blood pressure (BP) decrease, which may be due to a surge in atrial natriuretic peptide (ANP) and by suppression of sympathetic activity due to activation of mechanoreceptors by atrial distention. We hypothesize that size of the LAA, a compliant structure, affects atrial distension. Consequently, patients with smaller LAA remnants (i.e. more complete amputation) have more distension of the atrium and a more pronounced BP response upon LAA amputation. Methods We analyzed 33 patients with persistent AF from the MARK AF registry who underwent LAA amputation concomitant to thoracoscopic AF ablation. Systolic BP was measured at baseline, 12 hours (h), 24h, and 48h, 1 month, 1 year, and 2 years postoperatively. Complete amputation was defined as LAA remnant depth <10mm and a remnant LAA was defined as depth ≥ 10 mm on contrast enhanced CT 6 months post surgery. The postoperative LAA remnant/LA volume ratio was calculated by segmenting the atria and quantifying the volume of the contrast pools. T-tests and linear regression analyzed BP changes by remnant size and LAA remnant/LA volume ratio. Results were visualized using a boxplot and scatter plots with regression lines. Results 25/33 Patients had a LAA remnant. Baseline systolic BP was similar with 147 ± 31 mmHg in the complete amputation group vs. 137 ± 23 mmHg in the remnant group, p=0.389. Complete amputation correlated with greater systolic BP reductions in relation to baseline at 12h (-18%, p=0.018), 24h (-14%, p=0.025), 48h (-15%, p=0.028), 1 month (-20%, p=0.024), and 1 year (-16%, p=0.001), Figure 1. BP returned to baseline by 2 years in both groups. Lower LAA remnant/LA volume ratios were significantly associated with greater systolic BP reductions at 12h (β=7.4, p=0.005), 24h (β=9.9, p<0.001), 48h (β=10.1, p=0.002), and 1 month (β=11.1, p=0.01), Figure 2. However, this association was not observed at 1 and 2 years. Conclusion Patients with smaller LAA remnants after LAA amputation experienced a more pronounced transient reduction in blood pressure. Our findings suggest that increased atrial distension—due to the loss of compliant LAA tissue—could play a key role in modulating hemodynamics via sympathoinhibition and suppression of the Renin-Angiotensin-Aldosterone System (RAAS). Further investigation is needed to confirm these results and explore the neurohumoral effects of LAA amputation.Figure 1 Figure 2

Increased epicardial adipose tissue attenuation on CT images was associated with the presence and recurrence of atrial fibrillation in studies using consistent or corrected tube voltage settings, suggesting its potential as a prognostic marker.