Intrathoracic Impedance Monitoring, Audible Patient Alerts, and Outcome in Patients With Heart Failure

Rehospitalization for Heart Failure

“…49 -52 Although changes in intrathoracic impedance track more closely with changes in filling pressures, sensitivity and specificity for individual patients is low, and remote management guided by impedance monitoring has been associated with a disappointingly higher frequency of heart failure hospitalizations and worse clinical outcomes. 53 Therapy adjusted to the physiological signal of pulmonary artery pressures measured directly with implantable monitors was associated with a 39% reduction in heart failure hospitalizations in the CardioMEMS Heart Sensor Allows Monitoring of Pressure to Improve Outcomes in NYHA Class III Patients (CHAMPION) trial. 54 Wireless transmission of directly measured left atrial pressures to a handheld device has also been used to empower patients to self-adjust diuretics with guidance from the heart failure team, thus tightening the feedback loop around the patient.…”

Refined heart failure detection algorithm for improved clinical reliability of OptiVol alerts in CRT-D recipients

“…Yu et al [2] developed a detection algorithm called OptiVol TM to predict cardiac decompensation by applying Fluid Index derived from the changes of intrathoracic impedance, as a marker of lung fluid status. However, the reliability of OptiVol remained contradictory in further clinical trials [3,4]. In the prospective multicenter PARTNERS HF study (Program to Access and Review Trending Information and Evaluate Correlation to Symptoms in Patients with Heart Failure study), the clinical utility of impedance monitoring could have been improved by using a combined device diagnostic algorithm based on additional parameters such as: new onset of atrial fibrillation (AF), rapid ventricular rate during AF, low patient activity levels, high night heart rate (HR), low heart rate variability (HRV), low percentage of biventricular pacing, and ventricular arrhythmias with implantable cardioverter-defibrillator (ICD) shocks [5,6].…”

Fluid-Volume Assessment in the Investigation of Acute Heart Failure

“…Other studies have established that intrathoracic impedance and audible alerts actually increased hospitalization (hazard ratio 1.79, p = 0.022) compared to the controls [45]. This finding might be from improper hospitalization from overreaction to the alert itself.…”