Aortic regurgitation as a cause of sudden cardiac death with aortic and left ventricular remodelling - the role of the bicuspid valve

Abstract

Background and objective

Aortic regurgitation (AR) results in blood flow from the aorta back into the left ventricle, which leads to left ventricular hypertrophy and dilation which, in a clinical setting, leads to heart failure and death. However, it is not a well-recognised cause of sudden cardiac death (SCD).

Methods

We identified 10 cases of AR with no other cause of death from our database of 8,551 cases of SCD. All these cases had a full autopsy with negative toxicology. Diagnosis of AR was based upon the presence of prominent ridges on the edge of the aortic valve (AV) cusps with aortic root dilatation, and no significant calcification within the cusps. We measured heart weight, circumference of aortic annulus and ascending aorta, diameter of left ventricle, and circumferential left ventricle wall thickness prospectively. Cases were age and sex matched 2:1 to individuals with morphologically normal hearts with normal aortic valves.

Results

Age was 43±14 years, with 7 males and 3 females in the AR group, and 14 males and 6 females in the control group. Heart weight was significantly higher in individuals with AR compared to controls (642±200g vs 370±75g, p<0.001). All cases showed thick regurgitant ridges on the edges of all valvular leaflets macroscopically. The aortic annulus circumference (73±14mm vs 54±7mm, p<0.001) and the circumference of the ascending aorta (85±27mm vs 56±7mm, p<0.001) were significantly dilated in AR. The left ventricular cavity diameter was significantly larger in AR (52±15mm vs 30±8mm, p<0.001). There was no significant difference seen in maximal wall thickness of the left ventricle (16±6mm vs 14±2mm, p=0.068). 7 out of 10 AR cases had bicuspid aortic valves (70%) while two were rheumatic and one just had a dilated aorta. Microscopically, left ventricular fibrosis was seen in 7 of the AR cases (70%).

Discussion

AR is a rare cause of SCD, most commonly associated with bicuspid aortic valve. It can be recognised by prominent ridges on the AV cusps and/or thickening of the cusp free margin with aortic annular dilatation. It is only considered significant as a cause of death when found with increased heart weight, left ventricular dilatation, and/or ventricular fibrosis in the absence of other cardiac pathology. We demonstrate that there is a strong association between BAV, AR and SCD. As BAV is a congenital condition, clinical or surgical intervention could potentially prevent subsequent cardiac enlargement and fibrosis, thereby preventing SCD.