Figure 1: Normal ECG with no ischemic changes
He was diagnosed with acute exacerbation of dyspepsia and treated with a
single 8mg dose of ondansetron intravenously. Within a few seconds after
taking around 0.5ml (2mg) of ondansetron, the patient developed chest
tightness, redness and burning sensation around the injection site along
with urticaria, hypotension and bronchospasm. He was immediately treated
with hydrocortisone 100 mg intravenously, and the reaction resolved
within a few minutes. His vital signs were as follows: body temperature,
36.2°C; blood pressure, 90/60 mmHg; respiratory rate,20 breaths/min;
heart rate, 94 beats/min; and oxygen saturation, 88% on room air.
An ECG was obtained 15 minutes after administration of ondansetron which
showed no change from the baseline ECG. However, the patient’s cardiac
troponin T levels had elevated to 812ng/L, a 42x increase from his
previous levels. The patient was followed-up 15 minute later following
the reaction, where he complained of severe headache, dizziness and
fatigue. It was noted that the other symptoms had subsided. He was given
once-off aspirin loading dose of 312 mg orally. A subsequent ECG and
cardiac troponin was repeated every 6 hours and showed normal ECG and
serial drop in troponin levels of 231ng/L,178ng/L,128ng/L and 78ng/L}.
On follow-up, we inquired about his previous usage of ondansetron and
reported no history of drug or food allergies and no previous exposure
to ondansetron. Additionally, he does not have a history of surgery or
chemotherapy.
He was then referred to the cardiac center for complete cardiac
evaluation. An echocardiogram demonstrated mild left ventricular
hypertrophy with normal ejection fraction with no ischemic changes. He
also underwent a cardiac stress test and had no chest pain or ECG
changes. There was no indication for cardiac catheterization and the
patient was discharged. It was concluded that the sudden cardiac event
was most likely ondansetron-induced coronary spasm that resolved
spontaneously. Based on the allergic reaction that ensued prior to these
presentations, Kounis syndrome was suspected as a probable cause.