Myocardial Fibrosis in Aortic Stenosis (QF_SA_141)

This is a case of an 85 year old female smoker, with a past medical history of coronary artery disease status post coronary artery bypass grafting in 2013, hypertension, hyperlipidemia, aortic stenosis, carotid stenosis and obstructive sleep apnea. She was being medically managed for intermittently symptomatic heart failure, with chronic lower limb edema over the course of a decade. She had periodic echocardiograms to monitor her aortic stenosis.

Diagnostic Techniques and Their Most Important Findings:

On review of her electronic health record, a CMR had been performed in 2013 to evaluate for a left ventricular thrombus seen on echocardiogram. This demonstrated a 3.7 cm calcified thrombus in the left apex, with concentric left ventricular hypertrophy measuring up to 2.1 cm.

An echocardiogram in 2024 identified a new aneurysmal apical cap with concern for apical thrombus along with a dilated ascending aorta necessitating performance of chest MRA and CMR. CMR identified concentric left ventricular (LV) hypertrophy measuring up to 1.7 cm, with global LV systolic dysfunction. The apical cap was aneurysmal. There was diffuse, patchy late gadolinium enhancement (LGE) predominantly observed in the anterior and lateral segments, and apical cap (Figure 1). This was new compared with CMR from 2013 (Figure 2), other than a small focus of apical LGE seen observed previously. There was elevation of native T1 values measuring 1203 msec, and ECV was elevated at 41%. Quantitative left ventricular function was calculated at 48%. The aortic valve was trileaflet, with severely reduced coaptation in diastole. Qualitatively, severe aortic stenosis was observed on phase contrast and flow sequences. The peak velocity calculated was 2.9 m/s. The mid ascending aorta was mildly dilated measuring 3.8 cm.

Learning Points from this Case:

Myocardial fibrosis associated with aortic stenosis is not well described in the literature. The principal learning point is that when extensive patchy mid-myocardial LGE is demonstrated on CMR, observed in the setting of left ventricular hypertrophy with associated elevation in native T1 values and ECV, a reflexive diagnosis of cardiac amyloidosis must be avoided. However, in the setting of valvular disease or hypertension, alternative diagnoses, such as fibrosis associated with aortic stenosis or hypertension, must be considered.

            Cardiac amyloidosis typically affects myocardium with a basal to apical gradient. CMR was vital in confirming this diagnosis, in particular the MRI over a decade prior was instrumental in effectively excluding amyloidosis, by the presence of apical LGE.