Noninvasive myocardial imaging with potassium-43 and rubidium-81 in patients with left bundle branch block.

Noninvasive myocardial imaging with potassium-43 and rubidium-81 has been used successfully to identify areas of infarction and exercise-induced ischemia as regions of decreased radioactivity. The image defects observed are believed to be due to a decreased radionuclide uptake in regions of myocardial scar or to heterogeneous myocardial accumulation of tracer as a result of regional ischemia. Of 27 patients with left bundle branch block studied with noninvasive imaging at rest and during exercise, 25 manifested at rest reduced radioactivity in the region of the interventricular septum. This pattern is similar to that seen in patients with anteroseptal myocardial infarction. Sixteen of the 27 patients underwent diagnostic coronary arteriography and left ventriculography. Only five of these patients had evidence of either previous infarction or significant obstructive coronary artery disease as assessed with clinical or angiographic criteria, or both. Although the image defect was routinely demonstrated at rest in patients with left bundle branch block, this defect was generally normalized or less distinct with exercise in patients with no anatomic heart disease. In contrast, a larger, more distinct or new image defect with exercise correctly identified the presence of significant obstructive coronary artery disease in patients with left bundle branch block. In the clinical application of noninvasive myocardial imaging, these image defects observed at rest can lead to the false pasitive radionuclide interpretation of anteroseptal myocardial infarction.

Prevalence of clinical mitral-valve prolapse in 1169 young women.

Eleven hundred and sixty-nine young women were prospectively examined for the presence of mitral-valve prolapse as manifested by midsystolic non-ejection click or late systolic murmur (or both). Of the 1169 women 74 (6.3%) had physical findings consistent with mitral-valve prolapse. Sixty-eight of the 74 (92%) had midsystolic non-ejection click, and in 57 the click was accompanied by a late systolic murmur. In six (8%) only a late systolic murmur was heard. Echocardiography on all patients with clinical diagnosis of mitral-valve prolapse showed patterns of prolapse in 60 of 74 (81%). Fourteen (19%) had negative echocardiograms. We conclude that mitral-valve prolapse is clinically present in approximately 6.3% of otherwise healthy young women.

Clinical correlates of coronary cineangiography in young males with myocardial infarction.

Thirty-eight men who suffered acute transmural myocardial infarction before age 40, and after recovery were New York Heart Association functional Class I or II, were studied by noninvasive means and by coronary angiography in order to determine whether these nonivasive studies could predict the presence of significant coronary artery disease remote from that felt to be responsible for the previous myocardial infarction. Patients were divided into two groups on the basis of the absence (Group I) or presence (Group II) of obstructive disease in a major coronary artery supplying myocardium remote from the prior myocardial infarction. There were 21 patients in Group I and 17 patients in Group II. They did not differ with respect to age, abnormalities of lipid or glucose metabolism, family history, history of hypertension or cigarette use, presence of obesity, or infarct localization. Ten of 17 patients in Group II had angina pectoris; only 3/21 patients in Group I had angina pectoris (p less than 0.01). All 12 patients tested in Group II had a positive maximal exercise tolerance test; only 1/17 patients tested in Group I was similarly positive (p less than 0.001). The absence of angina pectoris and the presence of a negative maximal exercise tolerance test is strong evidence against the pressure of significant CAD remote from that responsible for the prior myocardial infarction.