252 - CONTRACTILE PROPERTIES OF PATIENTS WITH AORTIC VALVE STENOSIS UNGERGOING TRANSCATHETER AORTIC VALVE IMPLANTATION

Background: Contractile properties of the heart have not been adequately explored in patients with aortic valve stenosis (AS). Assessment of left ventricular contractile function is completed using strain echocardiography. Patients with AS have a depressed global longitudinal strain and peak left atrial longitudinal strain, representing subclinical systolic dysfunction. These contractile parameters increase and return to normal function following transcatheter aortic valve implantation (TAVI). Given that strain echocardiography is relatively new and requires specialized equipment and individuals to assess, a simpler method is needed to monitor the contractile properties of patients with AS. Seismocardiography (SCG) is a technique which records the vibrations produced by each heartbeat. By identifying the amplitudes of the force produced at different stages of cardiac cycle intervals allows for a rapid, non-invasive method to assess contractile function. The purpose of this study was to compare SCG-derived contractile properties in patients with AS prior to and following TAVI.

METHODS AND RESULTS: Patients with AS had their SCG (LLA Recordis; LLA Technologies Inc., Langley, BC) recording completed prior to undergoing TAVI and 24 hours following TAVI. The sensor was placed 1 cm above the xiphoid process of the sternum while the patient rested supine for approximately 1-minute. The sensor was turned on for 1-minute with the data collected on an SD card attached to the SCG sensor for subsequent analysis. The mitral valve and aortic valve opening and closing periods, and force produced by the contraction of both the left atrium and ventricle were recorded. Twist force was measured as the amplitude of the force produced from ventricular twist in milligravity (mG) using the SCG. Similarly, the amplitude of the force produced by atrial contraction was measured in mG. Using a paired sample t-test, the pre-TAVI to 24 hours post-TAVI contractile forces were compared. Twist force increased from 9 to 12mG (p < 10-6) post TAVI. There was also an increase in atrial systole from 6 to 9mG (p < 10-8) post TAVI.


Conclusion: Improvements in SCG-derived contractile parameters are apparent following TAVI in patients with AS. Twist force and atrial systole contractions as measured by SCG show the same degree of change following TAVI as global longitudinal strain and peak left atrial longitudinal strain. Continuously monitoring the contractile properties of the left ventricle and atrium by SCG can rapidly provide clinical information pertaining to subclinical changes in systolic function.