|
|
|
Clin. Cardiol. 23, 626–630 (2000)
John E. Madias, M.D., Predrag Knez, M.D., Moe Thu Win, M.D.
Mount Sinai School of Medicine of the New York University, and Cardiology Division of Elmhurst Hospital Center, New York, New York, USA
Summary: A 72-year-old man with exertional angina had a strongly positive exercise electrocardiogram (EECG) with a negative thallium-201 myocardial perfusion scintigram (Tl). Arteriography revealed triple-vessel coronary artery disease, for which he underwent aortocoronary bypass grafting. Repeat EECG was negative, and it was again associated with a negative Tl. The false-negative Tl on the first test was felt to be due to a rare phenomenon of homogeneously distributed reversible exercise-induced myocardial ischemia, leading to a uniform radiotracer count density. The even distribution of ischemia would also be expected to render a false-negative EECG, due to electrocardiographic cancellation, and this is frequently the case. However, in the patient presented herein, we propose that the ischemic cardiac apex rendered the EECG strongly positive because its position was not opposed by an ischemic muscular region, and thus an uncancelled ischemic ST-segment vector was generated. This hypothesis is supported by our recent work showing the unique role of the ischemic apex (among all the other myocardial territories) in rendering the EECG positive.
Key words: electrocardiogram (ECG), exercise ECG, thallium scintigraphy, ECG cancellation, true-positive exercise ECG, false-negative thallium test
Address for reprints:
John E. Madias, M.D.
Chief, Division of Cardiology
Elmhurst Hospital Center
79-01 Broadway
Elmhurst, NY 11373 USA
Received: July 6, 1999