Distinct atrial remodeling in valvular heart disease: insights from strain imaging and electrophysiological mapping

Background

Atrial remodeling is a key substrate for arrhythmogenesis in patients with valvular heart disease. Aortic valve disease (AVD) is primarily associated with pressure-overload, while mitral valve disease (MVD) commonly leads to volume-overload, resulting in distinct changes in structural, functional, and electrophysiological properties. Pressure-overload typically impairs atrial contractile function, whereas contractile function tends to remain preserved longer during volume-overload. Changes in contractile function can be evaluated non-invasively using strain imaging (contractile remodeling), and in electrical modeling by intraoperative epicardial mapping. We hypothesize that the slope of LA contractile strain (Sct), integrating both contractile deformation and contractile duration, is associated with distinct electrical remodeling in AVD versus MVD due the different pressure- and volume-overload mechanisms.

Purpose

To determine whether differences in Sct slope reflect distinct electrical remodeling patterns between AVD and MVD at a high-resolution scale (2mm).

Methods

Intraoperative, high-resolution, epicardial mapping (192 unipolar electrograms) of the left atrium (LA) and pulmonary veins (PV) was performed during sinus rhythm in patients undergoing surgery for AVD (n=32) or MVD (n=28). Unipolar potential voltages, potential fractionation, conduction delay (CD: ≥7ms) and conduction block (CB: ≥12ms) were measured. Preoperative transthoracic echocardiograms provided LA reservoir (Sr), conduit (Scd), and Sct strain values. Cycle durations, area under the curve (AUC), and the slopes of both the Sr and Sct phases were calculated based on the strain curves.

Results

A total number of 220.718 potentials were analyzed (AVD: 131.322, MVD: 89.396) and 60 LA strain measurements were performed. AVD patients showed higher LA Sct compared to MVD patients (17.5 vs. 11.6, p=0.003). Electrophysiological properties were broadly comparable (p=0.001), although AVD patients exhibited more potential fractionation, especially around the PV (p<0.001).

Stratification by Sct slope revealed opposing remodeling patterns. In AVD, steeper slopes were associated with shorter CB lines (p=0.032) and less variation in potential voltages (p=0.023). In MVD, steeper slopes related to a slower LA conduction velocity (p=0.024), as well as, more (p=0.074) and longer (p=0.026) CB lines, and more potential fractionation (p=0.028) around the PV. The difference in correlation strength between groups was significant for multiple pairs (z=2.0–2.8, p<0.05).

Conclusion

AVD and MVD show distinct atrial remodeling patterns: Higher Sct slopes in AVD are associated with shorter CB lines and lower voltage variability, whereas in MVD they relate to slower conduction and more PV conduction abnormalities. These findings highlight disease-specific atrial remodeling, and the complementary value of strain imaging in arrhythmogenesis.Figure 1