Myocardial adaptation after surgical therapy differs for aortic valve stenosis and hypertrophic obstructive cardiomyopathy

Abstract

Surgical therapies in aortic valve stenosis (AVS) and hypertrophic obstructive cardiomyopathy (HOCM) aim to relief intraventricular pressure overload and improve clinical outcome. It is currently unknown to what extent myocardial adaptation concurs with restoration of intraventricular pressures, and whether this is similar in both patient groups. The aim of this study was to investigate changes in myocardial adaptation after surgical therapies for AVS and HOCM. Ten AVS and ten HOCM patients were enrolled and underwent cardiac magnetic resonance cine imaging and myocardial tagging prior to, and 4 months after aortic valve replacement (AVR) and septal myectomy, respectively. Global left ventricular (LV) analyses were derived from cine images. Circumferential strain was assessed from myocardial tagging images at the septal and lateral wall of the mid ventricle. Pressure gradients significantly decreased in both AVS and HOCM after surgery (p < 0.01), with a concomitant decrease in left atrial volume (p < 0.05) suggesting lower diastolic filling pressures. Also, LV volumes, mass and septal wall thickness decreased in both, but to a larger extent in AVS than in HOCM patients. AVR improved wall thickening (p < 0.05) and did not change systolic strain rate. Myectomy did not affect wall thickening and reduced septal systolic strain rate (p = 0.03). Both AVR and myectomy induced positive structural remodeling in line with a reduction of pressure overload. A concomitant recovery in systolic function however was found in AVR only. The systolic functional deterioration in HOCM patients seems to be inherent to myectomy and the ongoing and irreversible disease.

Keywords: Aortic valve stenosis; Cardiac remodeling; Hypertrophic obstructive cardiomyopathy; Magnetic resonance imaging.

Fig. 1

Representative tagging images of a patient with AVS and HOCM with corresponding strain signals. a At end-diastole and end-systole representative images are shown for a patient with AVS (left) and HOCM (right) before (pre) and after (post) surgical treatment. b Corresponding peak circumferential strain and systolic circumferential strain rate curves are presented

Fig. 2

Global longitudinal strain. Global longitudinal strain is depicted for AVS before (pre) and after (post) surgery, HOCM before (pre) and after (post) surgery and healthy controls. AVS patients showed similar longitudinal strain compared with healthy controls both before and after AVR therapy. HOCM patients revealed a significantly lower longitudinal strain compared with healthy controls even after myecomy. †p < 0.01 versus controls. *p < 0.05 follow up versus baseline. All data is presented by median with interquartile range. AVS  aortic valve stenosis; HOCM   hypertrophic obstructive cardiomyopathy

Fig. 3

Change after surgery between AVS and HOCM. Change after surgery between AVS (n = 10) and HOCM (n = 8) are depicted for LV myocardial mass, left atrial volume, circumferential strain and regional systolic and diastolic stain rates. Values above zero in strain rates indicate improved strain, values below zero indicate reduced strain. An asterisk (*) indicates significant change within AVS or HOCM before vs after surgery (p-values are mentioned in Tables 2, 4). All data is presented by median with interquartile range. After surgery, HOCM demonstrates deterioration of septal systolic strain rate compared with AVS. Changes after surgery in regional diastolic strain rates were similar in HOCM compared to AVS. AVS  aortic valve stenosis, HOCM  hypertrophic obstructive cardiomyopathy, LA  left atrial, LV  left ventricular