Abstract
Risk stratification models using integrated device diagnostics have been developed to predict heart failure (HF) events. However, effective management strategies to reduce this HF risk have not been developed. The purpose of the INTERVENE-HF study was to determine whether a physician-directed, nurse-implemented ambulatory medication intervention strategy could be safely and effectively instituted in HF patients with an increased HF risk score.
A prospective, non-randomized, single arm, multi-center feasibility study was conducted in HF patients implanted with a Medtronic CRT-D device with Triage HF dynamic risk score (HFRS) diagnostic feature. HFRS was based on Bayesian analysis of CRT-D measured variables: transthoracic impedance, heart rate, heart rate variability, arrhythmia parameters, and activity. Ambulatory medication intervention strategy was remotely implemented by certified HF nurses (CHFN) following a guided action pathway triggered by a risk based alert. CHFN received alert notification to evaluate a patient when there was an impedance based OptiVolTM fluid threshold crossing. Patients not excluded due to safety or protocol-mandated criteria were managed by CHFN using a personalized, 3 day course of diuretic up titration (PRN Tx) prescribed by a physician at enrollment. Safety was monitored through daily CHFN remote review of weight, blood pressure and symptoms. Sufficient recovery after PRN Tx was defined as ≥ 70% recovery of impedance to baseline levels on day 4. If recovery criterion was not met on day 4, a second PRN Tx was initiated and impedance was reassessed on day 8.
66 patients had the alert feature enabled and were followed by CHFNs for 8.2 ± 3.9 months. CHFNs received alerts triggered by 49 OptiVolTM crossings. 23 of 49 crossings were not acted on due to safety or protocol-mandated criteria. 26 of 49 crossings received PRN Tx, 19 with 1 round, 7 with two rounds. Of 26 PRN Tx, 22 were completed, 19 led to ≥ 70% impedance recovery within 4 - 8 days. 4 interventions were stopped early for safety without leading to a serious adverse event (AE). 1 of 26 PRN Tx was followed by a HF event within 30 days of PRN Tx. Safety endpoint (# of PRN Tx without PRN Tx AE / # of PRN Tx) was 22/26 (85%). Effectiveness endpoint (# recovered without HF event within 14 days and without PRN Tx AE / # of PRN Tx) was 18/26 (69%).
An individualized risk stratification based ambulatory medication intervention strategy that is physician-directed and CHFN-implemented can be safely and successfully instituted in HF patients using an integrated device diagnostics based HF risk score.