(P089) CARDIAC CYCLE TIMING INTERVALS IN PATIENTS WITH AORTIC VALVE STENOSIS UNDERGOING TRANSCATHETER AORTIC VALVE IMPLANTATION

Background: Hemodynamic assessment of patients with aortic valve stenosis (AS) requires extensive resources including echocardiography and cardiac magnetic resonance imaging (MRI). Patients with AS have an elevated left ventricular ejection time, along with a shortened isovolumic relaxation time (IVRT) and Tei index. Deriving these cardiac cycle timing intervals is both timely and expensive. Seismocardiography (SCG) provides a rapid, non-invasive method for measuring cardiac cycle timing intervals by recording the vibrations produced by each heartbeat to identify the fiducial points pertaining to the aortic valve opening (AVO) and closing (AVC), and mitral valve opening (MVO) and closing (MVC). This study describes the cardiac cycle intervals and their post-operative changes in patients with AS using SCG.

METHODS AND RESULTS: Patients with AS were enrolled to complete an SCG (LLA RecordisTM; LLA Technologies) recording. The SCG sensor was placed directly on the patient’s skin, 1 cm above the xiphoid process of the sternum. The patient rested supine for ~1 minute before turning the sensor on to collect the data for 1-minute. This was completed prior to the patient undergoing transcatheter aortic valve implantation (TAVI) and 24 hours following TAVI. Following identification of the fiducial points from the vibrational activity, the following intervals were derived: ejection time (AVO – AVC), isovolumic contraction time (IVCT; MVC – AVO) and IVRT (AVC – MVO). From these intervals, the SCG-derived Tei index [(IVRT+IVCT)/ejection time], diastolic performance index (DPI; IVRT/ejection time), and systolic performance index (SPI; IVCT/ejection time) were calculated. A paired sample t-test was used to compare the pre-TAVI to 24 hours post-TAVI intervals. Patients (n=100) were 80 ± 6 years old, with 69% being male. The most prevalent comorbidities were hypertension (85%), dyslipidemia (68%), and diabetes (38%). Ejection time decreased from 333ms to 297ms (p < 10-8), while IVRT increased from 85ms to 90ms (p < 0.001). The Tei index increased from 0.37 to 0.43 (p < 10-9), while SPI (p < 0.01) and DPI (p < 10-10) increased from 0.11 and 0.26 to 0.12 and 0.31, respectively.

Conclusion: SCG-derived cardiac cycle intervals suggest a reduction in systolic time, and an increase in the Tei index, DPI and SPI following TAVI. These findings agree with previous catheterization lab and echocardiography derived cardiac indices in patients with AS undergoing surgery and add further insights to both systolic and diastolic function post-TAVI. Using SCG provides a simple alternative to monitor cardiac cycle intervals in patients with AS.