Rare Case of Iatrogenic Myocardial Infarction Induced by Use of Pyridostigmine

Abstract

Myasthenia gravis is an auto-immune disease that results in muscle weakness caused by antibodies released against acetylcholine receptors at the presynaptic membrane. Treatment options include acetylcholinesterase medications that cause a wide range of side-effects by increasing the concentration of acetylcholine at the synaptic cleft. One peculiar side effect seen is the precipitation of myocardial infarction caused by an excess of acetylcholine especially among elderly females. We present an interesting case of an 88-year-old female with a history of lung cancer newly diagnosed with paraneoplastic myasthenia gravis, started on treatment with prednisone 40 mg daily, and pyridostigmine 60 mg every six hours. She initially showed remarkable improvement in symptoms within a few hours, however, one day later, the patient developed sudden onset of chest pain radiating towards her left arm. A 12-lead electrocardiogram (EKG) showed diffuse ST-elevation in anterior leads and cardiac enzymes were found to be elevated. Pyridostigmine was stopped and the patient was started on heparin. The patient underwent cardiac catheterization which showed 50% stenosis in the right coronary artery (RCA) and 70% in the left anterior descending artery (LAD). The patient was monitored in the cardiac care unit (CCU) for 24 hours and later on discharged home on oral prednisone. It is a common practice to start treatment with anti-cholinesterase medications in newly diagnosed patients of myasthenia gravis, however, these medications can precipitate myocardial ischemia by coronary vasogenic spasm or by their arrhythmogenic effect. It is important to be aware of these outcomes while starting patients on these medications.

Pyridostigmine-induced coronary artery spasm in early-onset myasthenia gravis: a case presentation and review of the literature

“…Unlike acetylcholine, pyridostigmine is rarely reported as a trigger of CAS, and only four published cases of pyridostigmine-induced CAS have been reported to date (table 1). 1–4 One case is early-onset MG, age <50 years old, while others are late-onset MG. Gender preference in MG is bimodal; in other words, the prevalence of late-onset MG is higher in men and vice versa 10.…”

“…Given the lack of publication regarding the rechallenge of pyridostigmine in patients with suspected pyridostigmine-induced CAS, the neurocardiologist team decided to discuss rechallenge with the patient in light of the following reasons: (1) pyridostigmine is the first-line and effective management for controlling MG symptoms; (2) the patient had ever received pyridostigmine with a dose of 120 mg/day without developing CAS. Moreover, all of the previous publications reported that CAS occurs at a higher dose of pyridostigmine (180–240 mg/day)2 4; (3) pyridostigmine-induced CAS is very rare and is the provisional, not definite, diagnosis and (4) CAS can spontaneously occur without a precipitator. Hence, we cannot confidently conclude that pyridostigmine is the cause of CAS before the rechallenge.…”

“…Once the diagnosis is confirmed and the risk of myocardial infarction and fatal arrhythmia is compared with the benefit of MG symptoms control, pyridostigmine withdrawal is a preferred choice, particularly when alternative treatments are available 2 4. Apart from pyridostigmine, immunosuppressive agents (eg, corticosteroid, azathioprine, mycophenolate mofetil, etc) are indicated when MG symptoms cannot be controlled with pyridostigmine alone, or pyridostigmine is contraindicated.…”

“…Pyridostigmine, an acetylcholinesterase inhibitor used for controlling myasthenia gravis (MG) symptoms, is an uncommon trigger of coronary artery spasm (CAS) 1–4. Although the prognosis of CAS is mostly benign, it can cause irreversible myocardial infarction and fatal arrhythmias such as ventricular fibrillation and sinus arrest 5 6.…”

An Unfortunate Case of Takotsubo Cardiomyopathy During Plasmapheresis for Myasthenia Crisis

“…Although it is a multisystem disorder, cardiac involvement is seen in 16% of cases. Pericarditis, myocarditis, arrhythmia, and TC are worth mentioning myasthenia gravis-related cardiac complications [4][5][6][7][8][9][10]. Previous analysis shows a 15 times greater prevalence of secondary TC following MC than the general inpatient population and twice the odds of all-cause mortality in these patients [11].…”