Exercise-related QT interval shortening with a peaked T wave in a boy with MEN 2 syndrome

Abstract

Multiple endocrine neoplasia 2 (MEN 2) is a hereditary syndrome associated with medullary thyroid carcinoma, pheochromocytoma (PCC), and hyperparathyroidism. PCCs in patients with MEN 2 are usually found in the adrenals after the manifestation of medullary thyroid cancer and are commonly bilateral and hormonally active. Unfortunately, a diagnosis of MEN 2 or PCC often is delayed until after the patient has developed an advanced MEN 2-related tumor. We present unusual electrocardiographic changes on exercise testing in MEN 2 syndrome. Transient peaked T waves and shortening QT during exercise stress testing may provide an early clue for undiagnosed PCC. <Learning objective: Stress testing is not just for the diagnosis of ischemia but it may be used to evaluate patients with symptoms that suggest exercise-induced arrhythmias. The pheochromacytoma is a disorder characterized by excess of catecholamines and is usually difficult to diagnose. Excessive sympathetic stimulation is toxic to myocytes and this toxicity may reveal itself as ECG changes such as peaked T waves and shortening of QT interval. Such changes on ECG during sympathetic stimulation such as exercise testing should raise the suspicion of pheochromacytoma.>

Is exercise-related QT interval shortening with a peaked T wave a specific electrocardiographic finding of pheochromocytoma?

“…In this issue of Journal of Cardiology Cases , Gungor et al report the case of a MEN2 male patient with exercise-related QT interval shortening with a peaked T wave [17] . The resting ECG showed normal QTc interval of 394 ms.…”

“…Several studies reported that the effect of catecholamine is one of the secondary causes of short QT interval [13] , [19] , [20] . Gungor et al speculated that acute and massive catecholamine release caused a direct toxic effect on myocytes which resulted in these electrocardiographic changes [17] . The plasma catecholamine during exercise test in this patient was not measured but is thought to have increased, because a previous study reported that the post-exercise levels of epinephrine and the epinephrine/dopamine ratio were significantly higher in pheochromocytoma patients compared to healthy controls [21] .…”