Left ventricular remodelling and hypertrophy in patients with aortic stenosis: insights from cardiac magnetic resonance imaging

Introduction

The response of the left ventricular myocardium to aortic stenosis has been incompletely characterised. Here, we sought to investigate the correlation between the severity of aortic stenosis and the hypertrophic response and to define the patterns of remodelling and hypertrophy with CMR.

Methods

Consecutive patients with moderate or severe AS (aortic valve area <1.5cm²), normal coronary arteries and no other significant valve lesion or cardiomyopathy were scanned by 1.5T magnetic resonance and compared with contemporary age- and sex-matched healthy, control subjects. The extent and patterns of hypertrophy were assessed from volumetric cine images. Valve severity was assessed by planimetry and velocity mapping. Asymmetric forms of remodelling and hypertrophy were defined as having a septal-to-lateral wall thickness ratio >1.5.

Results

Ninety-one patients (61±21 years;63% male) with aortic stenosis (AVA 0.93±0.32cm²) underwent CMR. The degree of hypertrophy was unrelated to aortic stenosis severity (p=0.53) and there was a wide variation in LV structure comprising normal ventricular geometry (n=11), concentric remodelling (n=11), asymmetric remodelling (n=11), concentric hypertrophy (n=33), asymmetric hypertrophy(n=15) and eccentric hypertrophy (n=10).

Asymmetric forms of remodelling and hypertrophy were observed in 29% of the cohort with considerable overlap in appearances (wall thickness 17±2mm) with hypertrophic cardiomyopathy. Figures 1, 2, 3, Tables 1, 2.

Figure 1

Cardiac magnetic resonance imaging definitions of LV hypertrophy and remodelling

Figure 2

Influence of the Aortic Valve Area on the indexed LV mass. Pearson correlation: R=0.068; P= 0.530.

Figure 3

Prevalence of the different patterns of remodelling and hypertrophy in aortic stenosis (% of total cohort)

Table 1 Univariate predictors of increased left ventricular mass

Table 2 Baseline data of aortic stenosis patients with different forms of remodelling and hypertrophy

Conclusions

We describe six different patterns of LV anatomic adaption to AS and wide variation in the degree of hypertrophy, which occurred independently of the severity of valve narrowing. These findings are likely to impact on imaging interpretation of aortic stenosis severity and may predict operative risk and the potential for reverse remodelling post-intervention.