A Case Report of Complete Heart Block in a 58-Year-Old Woman with Multiple Myeloma Treated with Carfilzomib: Implications for Risk Stratification in High-Risk Populations

Abstract

Carfilzomib, a proteasome inhibitor used to treat relapsed multiple myeloma, is linked to rare cardiac
complications. Complete heart block (CHB), though seldom reported, poses critical risks in patients with
multiple comorbidities. This case report illustrates the development of CHB in a patient with multiple myeloma
and high cardiovascular risk, underscoring the importance of risk-based monitoring rather than proposing a
new mechanism. A 58-year-old Iranian woman with relapsed multiple myeloma, acute coronary syndrome,
hypertension, dyslipidemia, type 2 diabetes, and hemodialysis-dependent chronic kidney disease (CKD)
developed CHB 48 hours after carfilzomib initiation. The Naranjo Adverse Drug Reaction Probability Scale
yielded a score of 3 (indicating a “possible” adverse drug reaction). Discontinuation of carfilzomib and
temporary pacemaker implantation restored hemodynamic stability. Although the patient’s hemodynamics
improved following pacing, she ultimately died due to septic complications unrelated to the arrhythmia. This
case demonstrates the complexity of attributing CHB to carfilzomib in a multimorbid patient. It highlights the
necessity of comprehensive cardiac evaluation and risk stratification in patients receiving proteasome inhibitors,
especially those with concurrent CKD, coronary artery disease (CAD), and polypharmacy.