A 64-year-old woman presents to her internist because of diffuse bone pain, fatigue, and a 20-pound weight loss. Routine blood tests showed a hematocrit of 25, a serum creatinine of 2 mg/dL.
Subsequently, serum and urine protein electrophoresis (SPEP/UPEP) are ordered and the findings are consistent with a diagnosis of multiple myeloma. An ECG is obtained.
What abnormality is present?