The Common Phenotype Of Polycythemia And Hypervolemia In Hospitalized Heart Failure Patients

Abstract

<h3>Background</h3> : Heart failure patients have wide variations in intravascular volumes which form the basis for disease initiation and progression and contribute to confusion in treatment strategies. Blood volume analysis (BVA) is a bedside blood test that measures with 98% accuracy intravascular volumes of a HF patient, including plasma and red blood cell volume (RBCV). Extremes in excess of red blood cell volume (polycythemia (P)) in HF patients have been associated with poorer outcomes including mortality. A not uncommon BVA phenotype is that of secondary P, with or without hypervolemia(P/Hypervol). We sought to further clarify the clinical correlates and outcomes associated with this phenotype in a mixed LVEF cohort of hospitalized HF patients and whether this phenotype would be detectable utilizing pHct or Hgb measures. <h3>Methods/Results</h3> : In a cohort of 245 consecutively admitted HF patients (142 men/103 women) with mixed EFs who underwent BVA guided care, 25 patients (10.2%) had P/Hypervol and 3 patients (1.2%) had P with normal or low total blood volume. The presence of this phenotype was equal in patients with HFrEF and HFpEF (52%/48%). P/Hypervol was observed less frequently in patients over 75 (p=0.03), and among patients with BMI>35 (p=0.07). Despite P, the peripheral Hct (pHct) was either normal (57.1%), or >10% below normal (39.3%), indicating that in a majority of patients excess red cells were accompanied by an excess of plasma and that pHct would not indicate P. The BVA-provided RBCV showed that in 93% of patients with P that diuresis alone would not be able to achieve euvolemia without extreme hemoconcentration. Patients with P or P/Hypervol were treated with therapeutic phlebotomy or sent for hematology consults to achieve euvolemia. In terms of outcomes at 30 days post-discharge, 12% of the phenotype were readmitted, similar to those with other phenotypes; no deaths occurred in the P/Hypervol phenotype within 30 days or 365 days. 30-day readmissions did occur (56%) in the phenotype similar to other phenotypes (62.3%). <h3>Conclusions</h3> : The P/Hypervol phenotype is common and worrisome for several reasons. Neither the pHct, the BMI or age is sufficient to identify this phenotype. The plasma and red blood cell volume (RBCV) expansion may hasten disease progression accounting for underrepresentation of older patients in this cohort. Further, the discrepancy in the pHct might lead clinicians to suspect that the patient has a dilutionally low pHct, when, in fact, they have an increased RBCV and a diuretic strategy alone will only hemoconcentrate the patient, increasing viscosity and risk of thrombotic events while not achieving euvolemia. BVA-guided assessment demonstrated the specificity to identify this phenotype. and raise the value of therapeutic phlebotomy to optimize volume and RBCV; this cohort merits improved BVA-guided evaluation to better discern the impact of this phenotype on HF outcomes.