ic testing for the screening, detec- cholesterol]. As can be seen from tion and evaluation of hypertension, the corrected equation, the LDL in a strategy designed to evaluate cholesterol would be overestimated hypertension during effort, as sug- with the original formula when S.I. gested by Wilson et al.’ units are used. Fortunately, the auAngel Cantor thors seemto have usedthe correctNoah Lie1 ed formula, as can be deducedfrom Beer Sheva, Israel the results provided. 22 January 1991 This mistake is common in the literature in North America,3-6 re1. WilsonMF, Sung BH, Pincomb GA, flecting the lack of familiarity with Lovallo WR. Exaggerated pressure response to exercise in men at risk for sys- S.I. units, since conventional units are still widely used. Authors and temic hypertension. Am J Cardiol 1990;66:731-736. reviewers of articles should try not 2. Davidoff R, Schamroth CL, Goldman to add to the existing confusion. A AP, Diamond TH, Cillieb AJ, Myburgh simple test to check if an equation DP. Post exercise blood pressure as a pre- can be used with both types of units dictor of hypertension. Aviation Space is to first make the calculation with Environ Med 1982;53:591-594. conventional units and then convert 3. Franz IW. Ergometry in the assessall results in S.I. units before redoment of arterial hypertension. Cardiology ing the calculation. If the final re1985;72:147-159, sults differ, the equation needsto be 4. Cantor A, Gold B, Gueron M, Cristal adapted before using it with S.I. N, Prajgord G, Shapiro Y. Isotonic (dynamic) and isometric (static) effort in the units. assessment and evaluation of hypertension: correlation and clinical use. Cardiology 1987;74:141-146. 5. Cantor A, Cristal N. Responses of blood pressure and heart rate in mild and moderate hypertension with Isradipine and propranolol. J Cardiovasc Pharmaco1 1990;15:s75-S78. 6. Cardillo C, Musumeci V, Savi L, Guardigli R, Mores N, Folli G. Effect of sustained release verapamil therapy on the blood pressure at rest and the pressor response to isometric exertion in hypertensive patients. Eur J Clin Pharmacol 1988;34:549-553.

Lipid Profiles Transplantation

After

Cardiac

In their article, Rudas et al’ reported to have estimated low-density lipoprotein (LDL) cholesterol with the Friedewald formula,2 in which the very low-density lipoprotein cholesterol is approximated as serum triglycerides divided by 5. Unfortunately, this equation can be applied without correction only if the results are expressedin mg/dl. When Systeme International (S.I.) units are used, the equation must be adapted because the conversion factors for triglycerides and for cholesterol are different. With S.I. units, the Friedewald formula becomes: LDL cholesterol = total cholesterol - [serum triglycerides/ 2.18 + high-density lipoprotein 566

Jacques Mass&, MD

Quebec City, Canada 26 November 1990 1. Rudas L, Pflugfelder PW, McKenzie FN, Menkis AH, Novick RJ, Kostuk WJ. Serial evaluation of lipid profiles and risk factors for development of hyperlipidemia after cardiac transplantation. Am J Cardiol 1990;66:1135-1138. 2. Friedewald WT, Levy RI, Frederickson DS. Estimation of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge. CZin Chem 1972;18:499-502. 3. Mass6 J. Changes in lipoproteins during weight loss (letter). N EngZ J Med 1989;320:668. 4. Mass6 J. Clinical chemistry reference intervals for healthy elderly subjects (letter). Am J Clin Nutr 1990;51:1115. 5. Mass6 J. Portable cholesterol analyzers (letter). JAMA 1990;264:1101. 6. Mass6 J. Effects of diet on serum lipids and apolipoproteins (letter). Am J Clin Nutr 1990;52:765.

Radionuclide Exercise Response in Young Asymptomatic Chronic Alcoholics

The article by Cerquiera et al1 uses both rest echocardiography and resting and exercise radionuelide ventriculography to test for the presenceof preclinical alcoholic cardiomyopathy in 25 asymptomat-

THE AMERICAN JOURNAL OF CARDIOLOGY VOLUME 68

AUGUST 15, 1991

ic chronic alcoholics aged