Asymmetric myocardial thickening in aortic stenosis

Background

Asymmetric wall thickening has been observed in aortic stenosis (AS) but the clinical importance is poorly understood. We hypothesized this pattern was associated with advanced remodeling and worse outcomes.

Methods

Left ventricular volumes, wall thickness and mass were assessed in 166 patients (70 [64, 76] years; 69% males) with cardiovascular magnetic resonance. Diffuse myocardial fibrosis was assessed using myocardial T1 mapping (partition coefficient, λ). In the absence of infarction, asymmetric wall thickening was defined as myocardial thickness ≥13 mm and opposing wall thickness ratio ≥1.5. High-sensitivity cardiac troponin I (cTnI) and brain natriuretic peptide (BNP) concentrations were used as markers of myocardial injury and decompensation, respectively. Aortic valve replacement and all-cause mortality were assessed at 1 year.

Results

Compared to patients with concentric wall thickening (n=69), those with asymmetric pattern (n=43) had increased diffuse myocardial fibrosis (λ values 0.48±0.04 versus 0.46±0.04, respectively; P=0.04) despite similar age, sex, systolic blood pressure (SBP), and left ventricular mass index (LVMi; Table 1 and Panel A; all P>0.10). Plasma cTnI and BNP concentrations were also increased independent of age, sex, SBP, AS severity and LVMi (both P<0.01; Panels B and C). Patients with asymmetric pattern had worst outcomes compared to those with concentric thickening and normal wall thickness (log-rank P<0.0001; Panel D).

Conclusions

In aortic stenosis, asymmetric wall thickening is associated with ventricular decompensation and a worse prognosis.

Funding

The study is supported by the British Heart Foundation.

Figure 1

Baseline characteristics of patients with concentric and asymmetric wall thickening.

Figure 2

Compared to patients with concentric wall thickening, patients with asymmetric wall thickening had smilar left ventricular mass index (A) but elevated high-sensitivity troponin I (B) and brain natriuretic peptide concentrations (C). Importantly, patients with asymmetric wall thickening had worst outcomes compared to those with normal and concentric wall thickening (D).