Acute non-Q-wave myocardial infarction: a distinct clinical entity of increasing importance.

Despite the increasing incidence of acute non-Q-wave myocardial infarction, controversy remains regarding its validity as a distinct pathophysiologic physiologic and clinical entity. Review of the data indicates that the controversy is more apparent than real. The pathophysiologic factor discriminating best between non-Q-wave and Q-wave infarction is the incidence rate of total occlusion of the infarct-related artery, approximately 30% in non-Q-wave infarction and 80% in Q-wave infarction. Patients with non-Q-wave infarction have a higher incidence of pre-existing angina than patients with Q-wave infarction; they also have lower peak creatine kinase levels, higher ejection fractions and lower wall-motion abnormality scores, which suggests a smaller area of acute infarction damage. However, patients with non-Q-wave infarction have a significantly shorter time to peak creatine kinase level and more heterogeneous ventriculographic and electrocardiographic infarct patterns. The in-hospital death rate is lower in non-Q-wave than in Q-wave infarction (approximately 12% v. 19%). The long-term death rates are similar for the two groups (27% and 23%), but the incidence of subsequent coronary events is higher among patients with non-Q-wave infarction; in particular, reinfarction is an important predictor of risk of death. Most of the differences in biologic and clinical variables between the two types of acute infarction can be related to a lower incidence of total occlusion, earlier reperfusion or better collateral supply in non-Q-wave infarction. Further study is needed to better characterize the long-term risk and to define the most appropriate therapies.

Perioperative myocardial infarction with coronary artery surgery: diagnosis, incidence and consequences.

Perioperative myocardial infarction is a potential consequence of coronary artery bypass surgery. The diagnosis is difficult due to multiple factors including postoperative chest discomfort, serum enzyme elevations and nonspecific electrocardiographic changes. No one test is reliable, but a combination of electrocardiogram, MBCK serum enzyme analysis and technetium pyrophosphate scanning should increase the probability of correct diagnosis. Using this method, the incidence of perioperative myocardial infarction in this study was six out of 100. Left ventricular function in the early postoperative period was adversely affected by perioperative myocardial infarction with a reduction in left ventricular ejection fraction (63 +/- 9% preoperative to 54 +/- 12% postoperative; P less than 0.05), whereas left ventricular ejection fraction was unchanged in the absence of perioperative myocardial infarction. The long term left ventricular function, however, appears to recover, and at two years after surgery there was no difference in rest or exercise left ventricular function between patients who suffered perioperative myocardial infarction versus those who did not. All patients with perioperative myocardial infarction survived to be discharged from hospital, and all returned for follow-up at two years. Their functional and work status was no different from those without perioperative myocardial infarction. This would suggest that, if patients survive a perioperative myocardial infarction, their long term functional status is no different from those patients without perioperative myocardial infarction.

Dilated right ventricular cardiomyopathy: Uhl's disease.

Uhl's disease is a rare disorder originally described in 1952 in an infant with severe diffuse right ventricular dysfunction with total absence of the myocardium. Uhl considered the disease to be congenital in origin. We report a patient with severe dilated congestive cardiomyopathy limited to the right ventricle but apparently developing in adulthood.

Serum high density lipoprotein cholesterol in patients with abnormal coronary arteries.

Previous studies showing the inverse relationship between high density lipoprotein cholesterol (HDL-C) and coronary artery disease were based on myocardial infarction survivors and presumably normal subjects. To determine whether a similar relationship exists between patients with abnormal coronary arteries (ACA) and those with normal coronary arteries (NCA), the serum HDL-C and other lipoproteins of these patients and those of a group of presumably healthy control subjects (CTL) were determined. The ACA males had lower HDL-C and % HDL-C but higher TG, VLDL-TG, LDL-C/HDL-C and VLDL-C/HDL-C than the NCA and CTL males. They also had higher VLDL-C and % VLDL-C than the CTL males. Adjustment of HDL-C for serum TG eliminated the difference in HDL-C between the ACA and NCA groups but that between ACA and CTL groups remained. The ACA females had lower % HDL-C than the NCA and CTL females. They also had lower HDL-C but higher LDL-C/HDL-C and VLDL-C/HDL-C than the CTL females. The NCA and CTL groups did not differ in any of the lipid variables, although the NCA group values were intermediate to those of the ACA and CTL groups. Using various lipoprotein profiles, it was possible to classify the patients into the 3 groups.

Aortocoronary bypass for critical stenosis of the left main coronary artery.

Over a 2-year period 33 patients with symptomatic stenosis (greater than 75%) of the left main coronary artery underwent aortocoronary bypass. Intra-aortic balloon counterpulsation was used preoperatively in only two patients as a therapeutic measure for medically unstable angina. There were no operative deaths. Follow-up study 3 to 27 months (mean 13.3 months) after operation revealed one death. Twenty-two patients were free of pain. The authors conclude that aortocoronary bypass surgery for severe stenosis of the left main coronary artery can be safely accomplished, without prophylactic use of intra-aortic balloon counterpulsation in the majority of cases, with an acceptable operative mortality and morbidity.

Anomalous origin of left main cononary artery from anterior sinus of Valsalva with myocardial infarction.

The origin of the left main coronary artery, or its branches, from the right or anterior sinus of Valsalva is a recognized congenital anomaly. The origin of the entire left main coronary artery from a separate ostium in the right sinus of Valsalva and its course to the right and behind the ascending aorta, in a living patient without associated congenital heart disease, has not been described. This anomaly was recognized as the cause of an anterior myocardial infarction in a 12-year-old girl, and it is the subject of this case report.

Use of computers in clinical electrocardiography: an evaluation.

The use of computers in clinical electrocardiography is increasing rapidly; however, the role of computers with respect to the electrocardiographer has not been established. At present all electrocardiograms (ECGs) processed by computer are also interpreted by electrocardiographers; hense effort is duplicated. In an investigation of whether conditions can be defined under which the electrocardiographer can use the computer more profitably by eliminating some of the duplication, ECGs recorded in a university teaching hospital were processed by a computer program and subsequently reviewed by 1 of 10 electrocardiographers. For ECGs interpreted as showing normal sinus rhythm the rate of agreement between computer and human reviewer was 99%. For those showing a normal ECG pattern (contour) the rate of direct agreement was only 88%. However, the rate of occurrence of clinically significant differences was only 1.64%; hence the rate of essential agreement for this classification was 98.36%. Other classifications with good agreement were myocardial infarction, sinus bradycardia and sinus tachycardia. Therefore, in circumstances comparable to those of this investigation it is feasible for electrocardiographers to use computers to reduce greatly their workload without compromising the quality of the service provided.