Bioimpedance Spectroscopy Offers An Objective Measure Of Heart Failure Stability During A Viral Pandemic

Abstract

Introduction: Given the ongoing Covid-19 pandemic, shortness of breath (SOB) has increased as the chief complaint reported by patients. Viral pneumonia, telehealth, and the rising incidence of heart failure (HF) have driven the need for objective measures for wellness and congestion. Misclassification of congestion and delay in diuretics have been a concern by cardiologists across a variety of health care settings. We report the likelihood of a bioimpedance spectroscopy (BIS) measurement, specifically the Heart Failure Index (HF-Dex), to match patient perceived change since previous clinic visit.Background: BIS provides an objective measure of fluid levels. A recent publication reported the median HF-Dex value for patients with HF was 48.8%, in comparison to a healthy population whose median HF-Dex was 44.8%. Further research showed that HF patients with a value >51% had an odds ratio (OR) of 4.25 for readmission within 45 days.Methods: Fifty-six (56) HF patients were enrolled, during the Covid-19 pandemic, at their routine HF clinic appointment. Perceived change in status since last visit was reported as either no change, improved, or worsening symptoms. We assessed medication changes at time of clinic visit. HF-Dex values were obtained but were not made available to the treating physician. Based on a healthy control value of 44.8%, we applied a 45% threshold below which patients were considered stable from an HF perspective. A cut-point of ≥51% was used to determine the likelihood of medication changes and diuretic up dosing in the current study.Results: Seven (7) of 56 patients had an HF-Dex of 45% or below; none of these patients had an intensification of diuretic dosing or reported worsening symptoms. Twenty-one (21) patients had a measure of 51% or more, of whom 6 reported worsening symptoms prior to their exam for an odds ratio (OR) of 6.6 (95%CI: 1.2-36, p=0.03). The OR for any medication change in the ≥51% group of HF patients was 4.5 (95%CI: 1.1-18, p=0.03). Looking strictly at diuretic change, there was an OR of 3.6 (95%CI: 1.1-12.0, p=0.03).Conclusions: BIS measures provide a unique objective data point to aid in pretest probability for congestion. Patients with a HF-Dex of ≥51% required higher rates of medication and diuretic changes. Subjectively, HF patients at ≥51% also felt worse which may help limit misclassification of congestion when SOB is the chief complaint. Conversely, patients at <45% had fewer diuretic dose changes and felt better overall. The ability to quantify congestion may assist in triage of patients presenting with SOB, as has increasingly been the case during the Covid-19 pandemic in clinic and acute care settings.