Most heart attack tracings look recognizably like heart attack tracings. A small subset do not, and one of those looks like the dorsal fin of a shark cutting across the page.
A man in his forties arrived at an emergency department with chest pain that had lasted six hours. His blood pressure had fallen to 80 over 50, his heart was racing, and crackles at the base of both lungs said fluid was already backing up. His electrocardiogram showed enormous triangular waveforms across leads V2 through V4 and in leads I and aVL, with the QRS complex, ST segment and T wave fused into a single giant deflection. An echocardiogram put his ejection fraction at 25 percent. Angiography found complete thrombotic occlusion of the left main coronary artery, the vessel that supplies most of the left side of the heart.
