# Bradycardia, Renal Dysfunction, Atrioventricular Node Blockade, Shock, and Hyperkalemia (BRASH) Syndrome: Clinical Features, Outcomes, and Therapeutic Implications

## TL;DR

BRASH syndrome is a rare but serious condition in elderly patients involving heart and kidney issues, often triggered by medications and leading to life-threatening complications.

## Contribution

This study provides the first detailed clinical analysis of BRASH syndrome, including its features, management, and outcomes in a real-world patient cohort.

## Key findings

- Most patients had hypertension, heart failure, and were on AV-nodal blocking medications.
- Common triggers included nephrotoxins, infections, and medication changes.
- In-hospital mortality was 15.7%, with high readmission rates post-discharge.

## Abstract

Introduction: BRASH syndrome, characterized by the combination of bradycardia, renal dysfunction, atrioventricular node-blocking agent use, shock, and hyperkalemia, is an increasingly recognized but underdiagnosed clinical pattern, particularly in elderly patients with multiple comorbidities. Data regarding its clinical presentation, management, and short-term outcomes remain limited.

Methods: We conducted a single-center retrospective cohort study including patients admitted to the emergency department between 2019 and 2022. Patients met clinical criteria including bradycardia, hyperkalemia (K+≥5.0 mmol/L), acute kidney injury (KDIGO) or acute-on-CKD, AV-nodal blocker use, and evidence of shock. Demographic characteristics, comorbidities, precipitating factors, treatments, and short-term outcomes were analyzed. Subgroup analyses were exploratory.

Results: Fifty-one patients were included. The mean age was 79.8 years (SD 10.6; range 48-102), with a balanced sex distribution. Hypertension (90.2%), heart failure (68.6%), atrial fibrillation (52.9%), and chronic kidney disease (25.5%) were common. Most patients were receiving beta-blockers (82.4%), angiotensin-converting enzyme inhibitors (68.6%), calcium channel blockers (37.3%), or digoxin (31.4%). Frequent precipitating factors included nephrotoxic exposure (49.0%), infection or sepsis (43.1%), dose initiation or escalation of atrioventricular node-blocking agents (43.1%), and hypovolemia (33.3%). Admission hyperkalemia was generally mild to moderate, with a median potassium level of 6.5 mmol/L (IQR 5.8-7.2). Management included intravenous calcium (72.5%), insulin with dextrose (72.5%), beta-agonists (88.2%), vasopressor support (33.3%), renal replacement therapy (11.8%), and pacing support (9.8%). In-hospital mortality was 15.7%. Post-discharge mortality was 2.3% at 30 days and 7.0% at 90 days, and hospital readmission within 90 days occurred in 41.9%.

Conclusions: Early recognition of BRASH syndrome is essential, as even moderate hyperkalemia may lead to significant hemodynamic compromise and organ support requirements in high-risk patients.