ABSTRACT
BACKGROUND: Heart failure is a global health problem, and elevated left atrial pressure (LAP) is a precursor to identifying decompensated heart failure. At present, out-of-hospital monitoring of patients with heart failure is mostly based on the patient's symptoms and signs, and the use of non-invasive technology is scarce. In this study, a non-invasive ballistocardiography (BCG) device was used to collect thoracic vibration signals generated by heartbeat. We collected these signals from more than 1,000 adults, including those with different heart diseases, and used a sensor system and a composite index related to LAP recognition named the LAP-index, to analyze them. This study aimed to verify the reliability and accuracy of the LAP-index in identifying elevated LAP within heart failure patients. METHODS: We prospectively included 158 patients with various extent of diastolic function, some of whom had various underlying diseases, and collected BCG and echocardiographic data using a cross-section methodology. The BCG signal was recorded from multiple optical fiber vibration sensors placed on the back of each patient. We adopted the 2016 ASE/EACVI echocardiography guideline as the standard for determining LAP level from echocardiography parameters. To evaluate the diagnostic efficacy of the LAP-index, we drew a receiver operating characteristic (ROC) curve and calculated the area under the ROC curve (AUC). RESULTS: The LAP-index of the 158 patients ranged from 6 to 32. Of them, 39 were diagnosed as high LAP by echocardiography, and 119 cases had normal or slightly elevated LAP. Comparison of the LAP-index results and echocardiographic results revealed the ROC c-statistic of the LAP-index for identifying high LAP was 0.86 (95% CI: 0.79-0.93; P<0.0001). When the LAP-index was at the best cut-off value of 15.5, the positive agreement rate between it and echocardiography LAP was 0.85, the negative agreement rate was 0.80, and the overall agreement rate was 0.81. CONCLUSIONS: The sensor system and the LAP-index, a composite index derived from BCG, have high reliability and accuracy in identifying elevated LAP, which provides a novel possibility for the non-invasive detection of hemodynamic congestion in heart failure patients.
ABSTRACT
BACKGROUND: Due to a high prevalence and morbidity rate, heart failure (HF) constitutes an immense economic burden on the global health care system. An increase in left atrial pressure (LAP) precedes the occurrence of any HF symptoms. In this study, we applied a novel non-invasive method of ballistocardiography (BCG) to extract early diastolic ventricular vibration waves [the BCG-B3 index, which corresponds to the third heart sound (S3) at the end of the rapid filling phase of diastole]. This study evaluated the predictive value of the BCG-B3 index for LAP in HF patients. METHODS: A total of 83 HF patients and 20 patients with underlying diseases were prospectively enrolled, and their cross-sectional BCG and echocardiography (ECHO) data were collected. BCG obtains a signal through a high-precision fiber-optic sensor placed on the patient's back. LAP or pulmonary capillary wedge pressure (PCWP) was estimated by the ratio of mitral inflow peak early diastolic velocity to the early diastolic velocity of the mitral annulus (E/e') or the Nagueh equation (LAP = 1.24 × E/e' + 1.9). To evaluate the diagnostic efficacy of the BCG-B3 index, a receiver operating characteristic (ROC) curve was plotted, and the area under the ROC curve (AUC) was calculated. The best cutoff value for the BCG-B3 index was determined by the maximum Youden index. RESULTS: The correlation coefficient between the BCG-B3 index and E/e' ratio was 0.51 (P<0.01). Under an optimal cutoff value of 55.13, the BCG-B3 index showed a positive consistency value of 0.93, a negative consistency value of 0.53, and an overall consistency value of 0.82 for identification of significantly elevated LAP. CONCLUSIONS: The BCG-B3 index derived by noninvasive BCG using a built-in fiber-optic sensor has important diagnostic value for identifying significantly elevated LAP in HF patients with high accuracy. BCG examination is not limited by place or the doctor's experience. Therefore, BCG can provide timely assessments for HF patients, enabling early diagnosis and treatment.
