Acute Decompensation Avoidance in Heart Failure Patients

About This Grant

Summary/Abstract Heart failure (HF) is a leading cause of morbidity, mortality, and hospitalization. HF is the second-most-common Medicare inpatient diagnosis, with one of the highest 30-day readmission rates of any illness. Monitoring of HF patients remains challenging. In the hospital, right heart catheterization (RHC) is commonly used for compre- hensive evaluation and management of HF patients. In the home, HF monitoring generally relies on the detection of symptoms, such as dyspnea, and nonspecific physical exam findings related to edema, such as weight gain. Such measures are subjective and not sufficiently sensitive to be translated into early detection and intervention. Acute decompensated HF (ADHF) is defined as the sudden or gradual onset of the signs or symptoms of HF and is characterized by varying degrees of hemodynamic change — e.g., increased heart filling pressures and de- creased cardiac output (CO). Hemodynamic assessment is critical to the accurate evaluation of HF, particularly in ADHF, but currently requires invasive RHC; as a serious intervention, RHC is rarely performed in hospitalized ADHF patients. The ability to noninvasively track hemodynamic changes in home and hospitalized HF patients offers strong potential to improve care in both groups and to reduce hospitalizations and rehospitalizations. Recently approved remote implantable hemodynamic monitoring (viz., CardioMEMS) has shown promise to reduce HF patient hospital admissions, but is costly and requires an invasive procedure, which makes it impractical for most patients. There is an unmet need for a low-cost, noninvasive hemodynamic monitoring tool. Circulation time (CT) refers to the time delay between the injection of an indicator into the heart or lungs and its detection distally. In ADHF, a prolonged CT can reflect elevated heart filling pressure (pressure overload), low CO, and increased pulmonary transit time (PTT) due to pulmonary congestion. The “Lung-to-Finger CT” (LFCT) is prolonged in the setting of HF and is inversely related to CO and PTT. Dynamic O2 desaturation, such as occurs during apneic episodes in sleep or brief exposure to breath holding while awake, can be used to measure the LFCT. We have expanded the concept by having patients inhale two or three breaths of 100% O2 to measure LFCT and developed an easy measurement method called the Acute Decompensation Avoidance in PaTients (ADAPT) system. Pilot demonstration shows that the 100% O2 LFCT method is feasible and reproducible within subjects. With its noninvasiveness, simplicity, low cost, and pleasantness, it holds promise for use by HF patients in both home and hospital settings. ADAPT will monitor and automatically report significant increases in LFCT, indicating hemodynamic worsening or incipient decompensation. Phase I will assess and demonstrate the feasibility of the ADAPT system in admitted ADHF patients before and after hospital treatment for decompensation, where LFCT values should decrease significantly following hospital interventions. Additionally, hemodynamic measures from non-HF patients undergoing RHC will be cor- related with their LFCTs. This will include patients with different combinations of filling pressures and COs.