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March 18, 1983

The Multiple Risk Factor Intervention Trial

Author Affiliations

Medford, Ore

JAMA. 1983;249(11):1437. doi:10.1001/jama.1983.03330350017013

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To the Editor.—  Most hypertensive patients treated vigorously with diuretics manifest variable lowering of serum potassium (K+) levels and, often, nonspecific ECG abnormalities. Low serum K+ levels increase myocardial irritability and the risk of cardiac arrhythmias and sudden death. Prevention of hypokalemia causes less risk than detection and later correction. Many cardiologists routinely administer supplemental K+ or K+-sparing agents concurrent with diuretics in patients with normal renal function. Evidence also suggests that a high K+ intake increases the effectiveness of antihypertensive therapy. The high mortality in hypertensive men receiving diuretic therapy with resting ECG abnormalities in the MRFIT was most probably related to low serum K+ levels. If contrary information is available, it should be promptly reported. It seems unlikely that unfavorable results were caused by "drug toxicity."