| Despite recent advances in its management, heart failure remains a major cause of disability and death and its prevalence is still increasing as the population ages. However, rapid and accurate bedside diagnosis, evaluation as well as risk stratification of heart failure still remain challenging.;Acoustic cardiography (AUDICOR, Inovise Medical, Inc., Portland, OR, USA) is a novel and user friendly equipment which can be used in a wide variety of clinical conditions. With proprietary dual-functional sensors, this technology permits simultaneous acquisition of detailed information regarding systolic time intervals and diastolic heart sounds and provides a computerized interpretation of the findings. Major acoustic cardiographic parameters include S3 score (probability that the third heart sound exists), electromechanical activation time (EMAT, interval from Q wave to the first heart sound; %EMAT is the proportion of cardiac cycle that EMAT occupies), and systolic dysfunction index (SDI= exp [S3 score/10] x QRS interval x QR interval x %EMAT). This thesis will cover 3 aspects of clinical application of acoustic cardiography in heart failure patients.;I. Identification of heart failure and its phenotypes: We performed one study involving 94 patients with hypertension without heart failure, 109 patients with heart failure with normal ejection fraction (HFNEF, EF > 50%) and 89 patients with heart failure and reduced ejection fraction (HFREF, EF < 50%). We found that %EMAT significantly differentiated HFNEF from hypertension. Whereas SDI out-performed the other acoustic cardiographic parameters in differentiating HFREF from HFNEF.;II. Assessment of HFREF patients at high risk by evaluating the severity of left ventricular (LV) systolic and diastolic dysfunction: Ninety-four hypertensive patients without heart failure and 127 HFREF patients (EF < 50%) were consecutively recruited for the study. SDI significantly differentiated HFREF from hypertension. In subgroup analysis, SDI discriminated HFREF patients with severely impaired EF (EF ≤ 35%) from those with moderately impaired EF (35% < EF 4.67 identified HFREF patients with restrictive LV filling pattern.;III. Risk stratification in patients with heart failure: A total of 474 patients hospitalized for heart failure were enrolled into our study. During a mean follow-up time of 484+/-316 days, 169 (35.7%) patients died and 125 (26.4%) of them died of cardiac causes. After controlling for other potential confounders, we found that S3 score ≥ 4.12, and SDI ≥ 5 were both independent predictors for all-cause mortality. Kaplan-Meier analysis showed that heart failure patients with SDI ≥ 5 or S3 score ≥ 4.12 had a significantly lower survival rate than those with lower SDI or S3 score.;In summary, this bedside technology offers a wide variety of clinical applications in (1) identification of heart failure and its phenotypes; (2) assessment of HFREF patients at high risk by evaluating the severity of LV systolic and diastolic dysfunction; (3) risk stratification in patients with heart failure. Thus, acoustic cardiography is likely to be helpful in the management of heart failure patients, acting as an early detection, evaluation and risk-stratification tool. |
