BRASH Syndrome: A Systematic Review of Reported Cases

Abstract

The pathophysiology of Bradycardia-Renal Failure-Atrioventricular Nodal Blockade-Shock-Hyperkalemia (BRASH) syndrome involves acute renal injury leading to ineffective clearance of AV nodal agents and potassium. Theoretically, the synergy between AV nodal blockade and hyperkalemic cardiac dysconduction results in circulatory collapse at less-than-expected doses of both. Our study aims to characterize the presentation of BRASH and provide clinical evidence of its risk factors. This systematic review comprises all reported cases of BRASH until February 2022. The average age and Charleston Comorbidity Index at presentation was 69 years and 3.8 respectively - hypertension (71%) was most prevalent followed by diabetes mellitus (48%) and chronic kidney disease (44%). The most frequent presenting complaint was fatigue or syncope (49%). More than half of all patients presented with nonsevere hyperkalemia (less than 6.5 mmol/L) and the mean serum creatinine was 3.6 mg/dL. Beta-blockers (75%) were the most commonly implicated nodal agents. Presenting mean arterial pressure was 62 mm Hg and heart rate averaged 36 bpm; junctional escape rhythm (50%), sinus bradycardia (17.1%), and complete heart block (12.9%) were generally observed on EKG. While most patients responded to medical management, 20% of patients required renal replacement therapy and 33% required transvenous or transcutaneous pacing. No patients underwent permanent pacemaker placement and the in-hospital mortality of BRASH was 5.7%. The diagnosis of BRASH requires a high index of suspicion; its synergistic pathology results in a dramatic clinical presentation that can be easily overlooked. As hypothesized, the degree of renal failure and hyperkalemia are not congruent with the presenting circulatory shock. The significant mortality of this syndrome presents an opportunity for intervention with timely recognition.