Abstract 15253: A Paradoxical Rise in Serum Copeptin After Non-Pulsatile LVAD: a New SIADH?

Introduction: Hyponatremia (Na< 136 mmol/L) is prevalent (~28%) among hospitalized heart failure (HF) patients and a marker of advanced/end-stage HF(AHF) with increased mortality. Treatment of hyponatremia has no survival benefit in this population. In a prospective study of AHF patients, we sought to define the prevalence, pathophysiology and role of V2 vasoreceptor activity in the development of hyponatremia. Serum copeptin (S-COP), a surrogate marker for AVP activity, was assessed during AHF therapies (AHFT) which included axial-non-pulsatile left ventricular assist device (LVAD) and/or heart transplant (HTx). Methods: Serum samples were collected from AHF patients pre and post AHFT and compared with normal controls. S-COP levels were assessed using an enzyme linked immunosorbant assay and correlated to clinical variables, serum Sodium (S-Na) and glomerular filtration rate (eGFR). Results: Among 89 consecutive (mean age 56.2±15.35; M=69) patients awaiting AHFT, 54 (60%) were hyponatremic. Preop S-COP was elevated compared to controls (0.68±0.50 vs 0.53±0.13 ng/ml, P=.02) and inversely correlated to S-Na and eGFR (r=-0.23, P<.05, r=-0.23, P<.05; N=81); conversely, eGFR and S-Na were uncorrelated. AHFT (n=42) normalized S-Na (133.2±4.1 vs 136.1±3.5 mmol/l; P=.001) and improved eGFR (47.7±13.6 vs 52.7±9.7 mL/min/1.73sqm; P=.001); however, post LVAD (n=34) S-COP rose (0.67±0.21 vs 1.84±0.76 ng/ml; P<.0001) with incomplete normalization of S-NA (132.9±4.3 vs 135.9±3.8 mmol/l; P<.01). In contrast, post HTx (n=9) S-COP was unchanged to pre-AHFT (0.59±0.32 vs 0.65±0.16 ng/ml; P>.1) and was lower compared to post LVAD (0.65±0.16 vs 1.84±0.76 ng/ml; P<.0001). Elevated S-COP with LVAD as bridge to transplant (n=3) showed a marked decrease post HTx (2.7±0.50 vs 1.0±0.29 ng/ml; P<.01). Conclusions: In AHF, the prevalence of hyponatremia is double compared to acute hospitalized HF and associated with S-COP surge prior to AHFT. Unexpectedly, LVAD but not HTx was associated with rising S-COP and incomplete S-Na recovery despite clinical improvement, suggesting inappropriate antidiuretic hormone release. The association of S-COP rise with non-pulsatile LVAD and potential benefit of long-term AVP inhibition post LVAD merits further studies.