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January 18, 1985

Hypomagnesemia Causes Coronary Artery Spasm

JAMA. 1985;253(3):342. doi:10.1001/jama.1985.03350270036005

To the Editor.—  Low extracellular magnesium (Mg) levels may cause coronary artery spasm.1 Increased influx of calcium across the arterial smooth-muscle cell membrane is the postulated mechanism.2 Nevertheless, one authoritative review of calcium channel-blocking agents does not mention Mg.3 Furthermore, I know of no case reports of hypomagnesemia causing cardiac ischemia. Therefore, the following brief report may be of interest.

Report of a Case.—  A 74-year-old woman was hospitalized because of syncope followed by chest pain. Past history included a myocardial infarction one month previously. At that time, her serum Mg level was 1.1 mg/dL (reference range, 1.4 to 2.0 mg/dL). Her chest pain had continued until she was given diltiazem, 30 mg orally three times daily. Coronary angiography one month before her myocardial infarction had shown no obstructive lesions, but ergonovine challenge was not performed. Twelve years prior to this, she had had a partial small-bowel