Abstract
Clinical HF is most commonly described by TTE analysis of LVEF and criteria for diastolic impairment elaborated by the American Society of Echocardiography (ASE) standard of 2016. However, a binary classification of HFrEF vs. HFpEF can oversimplify the complexity of impaired ventricular performance. CTIs are sensitive, integrated markers of cardiac hemodynamics, and have previously been demonstrated to contain prognostic information equivalent to the echo parameters in various populations. HEMOTAG is the first device to derive hemodynamics wirelessly via any smartphone using cardiac vibrations and an ECG signal transduced via multiple anterior chest wall electrodes. The purpose of this study was to assess the extent to which CTIs from echo and HEMOTAG are related to NYHA functional class and ASE diastolic impairment criteria.
Within a 4 months period 136 consecutive patients undergoing TTE were recruited at an outpatient office. CTIs by HEMOTAG and Echo along with TTE report and cardiologist report were recorded. Of those (136), 60 patients had HF with recognized NYHA Class as determined by treating cardiologist and echo data for ASE criteria of diastolic dysfunction. Data were analyzed using MATLAB 2014a.
Table 1 shows number of patients in three diastolic function groups plus a HFrEF group vs. NYHA Class. Fisher's exact test for independence between row and column factors produced p = 0.015, indicating that the number of patients in each heart failure group varied by NYHA Class. 2-way ANOVAs for each echo variable (TRmaxPG, E/e’, E, e’, E/A, LAVI) indicated that echo variables were sensitive to ASE criteria but not NYHA Class, while CTIs of AO (QRS to Aortic opening) and STR (AO/ET= QRS to Aortic opening /Aortic opening to Aortic closing) were sensitive to the interaction of NYHA Class and diagnosis. The results indicate that CTIs offer a unique perspective on the relationship between heart failure signs and symptoms and diagnosis.
Analysis of echo criteria for diastolic dysfunction indicated that echo variables varied by diagnosis but not NYHA Class. That is, the distribution of each echo variable for patients with no symptoms was not different from patients with severe symptoms. However, CTIs of AO and STR from Echo and HEMOTAG successfully demonstrated relationship between HF signs and symptoms and ASE diagnosis. Thus, CTIs may be a valuable tool to discriminate NYHA class better than echo measures of diastolic dysfunction. Larger studies are needed to further validate these findings.
