Increased extracellular volume after aortic valve replacement: A footprint of reverse ventricular remodeling that does not affect conduction velocity.

BACKGROUND

Extracellular volume (ECV) determined by cardiovascular magnetic resonance (CMR) is considered a marker of diffuse myocardial fibrosis and a predictor of mortality. Using personalized computational models, we investigated the relationship between ECV, conduction velocity (CV), and cell radius in aortic stenosis (AS) patients.

METHODS

CMR was performed on 12 AS patients (6 males, 6 females) before and three months after surgical aortic valve replacement (AVR). All patients had a QRS duration ≤110ms, and no scar on late gadolinium enhanced (LGE) CMR. Computational biventricular models were developed from each CMR dataset. Using patient-specific ECV and the relative change in cell radius between the time points as inputs, tissue conductivity was adjusted in each model to match the patient's QRS duration. A physiological pattern of ventricular depolarization was mimicked by simultaneously pacing each model from five activation sites. CV was measured during a simulation of apical pacing, using two points positioned at the right ventricular septum of the model.

RESULTS

Left ventricular mass decreased after AVR (62 [58-79] vs 51 [41-60]g/m2, p=0.0005) while ECV increased (24.2 [20.6-24.8] vs 28.0 [25.1-29.5] %, p=0.0008). No changes in the patient's QRS duration (89.0 [80.5-99.0] vs 88 [78.5-99.5]ms, p=0.2148) were observed. No changes in the CV obtained from the models (64.3 [61.9-72.8] vs 66.0 [60.0-74.5]cm/s, p=0.5186) were found between the time points, suggesting there was no substantial increase in diffuse fibrosis. ECV was negatively correlated with cell radius (r=-0.5267, p=0.0082), but not correlated with CV obtained from the models (r=-0.2036, p=0.3399).

CONCLUSION

Increased ECV three months after AVR in patients with no LGE scar and with normal ventricular conduction appears to be a footprint of reverse ventricular remodeling that does not necessarily translate into changes in myocardial CV.