Efficacy of a Nurse Practitioner Managed Outpatient Intravenous Diuresis Clinic to Relieve Recurrent Congestion in Patients with Cardiac Amyloidosis

Background Cardiac Amyloidosis (CAm) is an infiltrative disease caused by abnormal extracellular protein deposits in the myocardium, leading to restrictive cardiomyopathy. The cardinal clinical manifestation is congestion resulting in symptomatic heart failure (HF). Relief of congestion is achieved with high dose loop diuretics and regularly requires hospitalization for intravenous (IV) diuresis. Additionally, CAm is a challenge to manage given sensitivity to preload and afterload, low systemic blood pressures, and inefficacy of advanced therapies typically used in HF. Objectives To demonstrate successful management of patients with CAm, specifically safety and efficacy of outpatient IV diuresis, in a nurse practitioner-run diuresis clinic. Methods An observational study of patients with CAm managed in the Johns Hopkins Heart Failure Bridge Clinic (HFBC) from January 2017 through December 2017. Patients are seen independently by a nurse practitioner and need for IV diuresis is assessed with administration based on clinic protocol. Patients identified using electronic medical records and diagnosis codes via ICD-10 and Snomed. Results During the study period, 49 patients with CAm were seen in the HFBC 268 times, with an average of 5.47 (SD 5.7) visits per patient (range 1 to 21). Of the 49 patients, 37% were initially referred to HFBC post hospitalization and 61% were referred by an outpatient provider. Patients described New York Heart Association (NYHA) class III or IV symptoms at 221 (82%) of the encounters. Home oral loop diuretic regimens at each visit included 15 (6%) on no diuretic, 90 (34%) on furosemide, 135 (50%) on torsemide, and 28 (10%) on bumetanide. Additionally, patients were taking metolazone at 83 (31%) visits. On average, patients were taking an equivalent of 182 mg (SD 196) oral furosemide daily at their first visit. IV furosemide was administered 90 times, ranging from 0 to 16 times per patient. Average IV furosemide dose administered was 142 mg (SD 38). Additionally, there were 23 clinic administrations of oral metolazone. Patients receiving IV furosemide had a prediuresis creatinine 2.03 mg/dL (SD 0.7) and blood urea nitrogen 51 mg/dL (SD 23). Post-diuresis mean clinic urine output was 379 ± 221 mL and weight loss was 0.3 ± 0.3 kg. There was no significant difference in pre and post-diuresis blood pressure and no recorded adverse events such as symptomatic hypotension, severe hypokalemia or acute renal failure. Twenty two patients comprised 33 (12%) post hospitalization visits; these occurred an average 7.5 days post-discharge. Of these, 7 patients experienced a 30-day readmission a total of 9 times, 5 of which were for decompensated HF. Of all 268 clinic visits, 14 (6%) required need for further management with referral to emergency department or direct admission. Conclusion We demonstrate safe and effective management of CAm patients in a nurse practitioner-run outpatient diuresis clinic. Outpatient IV diuresis is generally well tolerated despite baseline low blood pressures and renal dysfunction. Regular follow up and the ability to administer outpatient IV diuretics to patients with CAm prevents hospitalization and reduces healthcare utilization in an otherwise high-risk patient population.