PD-1 Inhibitor-Induced Thyrotoxicosis Associated with Coronary Artery Spasm and Ventricular Tachycardia

Programmed cell death protein 1 (PD-1) inhibitors open a new era of cancer immunotherapy, but they are associated with immune-related adverse events (irAEs) involving multiple endocrine organs of which thyroid dysfunction is the most common An uncommon condition of coronary artery spasm and ventricular tachycardia associated with thyrotoxicosis, induced by a PD-1 inhibitor, is discussed in this case. A 60-year-old male patient with a 1-week history of chest tightness and palpitation at rest was referred to us in July 2021. No obvious abnormalities were noted on physical examination and electrocardiography. He was being treated with a PD-1 inhibitor (camrelizumab, 200 mg) for lung metastasis of liver cancer; treatment stopped because he was found to have hyperthyroidism. Holter recorded intermittent STsegment arch back raised 0.5-14 mm upward lasting for 1-5 min, accompanied by ventricular tachycardia. He was treated with antivasospasm drugs (isosorbide mononitrate and diltiazem). Thyroid function was reexamined and revealed elevated FT3 and FT4 levels, decreased TSH levels, and negative thyroid-associated antibodies. After antivasospasm treatment and iodine taboo diet, his symptoms were relieved, and ST-segment elevation and ventricular tachycardia were disappeared. This case adds to our knowledge of the association between coronary artery spasms and thyrotoxicosis, which is an irAE induced by a PD-1 inhibitor. Patients treated with PD-1 inhibitors need regular follow-ups for cardiac complications, especially those with a history of heart disease.