Key factors in the identification of the high-risk patient with unstable coronary artery disease: clinical findings, resting 12-lead electrocardiogram, and continuous electrocardiographic monitoring

Magnetocardiography predicts coronary artery disease in patients with acute chest pain

BACKGROUND

The value of magnetocardiography (MCG) for the detection of cardiac electrical disturbances associated with myocardial ischemia was studied.

METHODS

Sensitivity and predictivity of admission MCG for the presence of coronary artery disease (CAD) were prospectively evaluated in 264 consecutive patients presenting with acute chest pain and without ST-segment elevation. MCG findings were compared with 12-lead ECG, echocardiography (ECHO), and troponin-I in a head-to-head design. Coronary angiography was used for CAD diagnosis.

RESULTS

The visual assessment of magnetocardiograms by the experienced reader (R1) was superior to that by the unexperienced reader (R2) and superior to the automated computer analysis. Specificity and positive predictive value of MCG by R1 were comparable with those of ECG and troponin-I (>90%), while ECHO specificity and ECHO positive predictive value were lower (76.2% and 87.9%, respectively). Sensitivity and negative predictive value of MCG were twice as high as those in the ECG, troponin-I, and ECHO tests.

CONCLUSION

For the prediction of CAD in patients presenting with acute chest pain and without ST-segment elevation, an admission MCG test was superior to an admission ECG, ECHO, and troponin-I. The results of the study, however, are applicable only to a highly selected population comprising patients in whom immediate coronary angiography can be performed based on their clinical course in the hospital.

ST-segment analyses and residual thrombi in the infarct-related artery: a report from the ASSENT PLUS ST-monitoring substudy

BACKGROUND

Evolution of the ST segment during ST-elevation myocardial infarction (STEMI) has been shown to yield more information on prognosis than widely used invasive measurements. With continuous ST monitoring, even very occasional dynamic changes can be analyzed. We have recently suggested that ST variability during the reperfusion-phase is of prognostic importance. We wanted to further investigate this and relate it to angiographic findings.

METHODS

A total of 177 patients with STEMI were examined in the ST-monitoring substudy of the ASessment of the Safety and Efficacy of a New Thrombolytic (ASSENT) PLUS trial, comparing dalteparin with heparin as adjunctive therapy to t-PA. Patients underwent 24 hours of ST monitoring. These recordings were blindly analyzed by 2 independent observers. A coronary angiogram was performed on days 4 to 7, also blindly evaluated by 2 persons.

RESULTS

Occurrence of ST re-elevations during and after the reperfusion-phase was significantly associated with residual thrombi and TIMI-flow in the infarct-related artery. Patients without any ST re-elevations showed a thrombus in only 5% of cases, as compared with 86% of patients with prolonged (lasting >30 minutes) ST re-elevations. In a multivariate comparison including baseline-data and treatment, most information on persistence of thrombi was contributed by the presence of any ST re-elevations (odds ratio, 5.8; 95% CI, 1.3-26).

CONCLUSION

ST re-elevations during the first day of an acute myocardial infarction are associated with residual thrombi in the infarct-related artery even 4 to 7 days after the STEMI.

[Biological markers of myocardial necrosis]

New biological markers of myocardial injury have improved the management of patients with acute coronary syndromes. Among these markers, the most relevant are the cardiac troponins (troponin I and troponin T) because of their cardiospecificity, and myoglobin because of its combination of diagnostic sensitivity and usefulness for an early diagnosis. The serial analysis and combined use of both markers fulfill all diagnostic and prognostic requirements, and are helpful in indicating therapeutic strategies for acute coronary syndromes. However, these markers also have limitations, and their concentrations should always be interpreted in the light of the patient's clinical status.

Prodromal unstable angina in acute myocardial infarction: prognostic value of short- and long-term outcome and predictor of infarct size

BACKGROUND

An estimated 50% of patients with myocardial infarction have prodromal unstable angina. There is controversy over whether prodromal unstable angina identifies a group of patients at lower risk of short- and long-term death and the clinical importance of recording this event.

METHODS

Of 207 patients enrolled at a single Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-I) site, 196 survived the 24 hours after presentation, achieved peak creatine kinase MB concentrations, and were classified as having either abrupt symptom onset or prodromal unstable angina in the 2 weeks before myocardial infarction. Creatine kinase MB peak was used to categorize infarct size as aborted myocardial infarction, minor myocardial damage, or extensive myocardial injury. Follow-up was performed at 24 hours, 30 days, 1 year, and 5 years. Multiple variables, including prodromal unstable angina, time to treatment, age, sex, previous infarction and infarct location, were analyzed for predicting infarct size. Also, these variables plus peak creatine kinase MB level and a combined variable of prodromal unstable angina and peak creatine kinase MB level were examined for predicting survival.

RESULTS

Mortality rate was 2.5% within 24 hours, 9.0% at 30 days, 13.5% at 1 year, and 27.1% at 5 years. Patients categorized as either aborted infarction or minor myocardial damage were significantly more likely to have prodromal unstable symptoms (81.3% vs 51.2%, P <.001) and better survival at each follow-up period. Prodromal presentation was the most significant predictor of infarct size category (P =.001). Five-year survival was predicted by age (P <.0001), peak creatine kinase MB level (P =.007), infarct location (P =.009), the combined variables (P =.029), and prodromal unstable angina (P =.017). Prodromal unstable angina had the highest odds ratio for 5-year survival at 3.83 (95% confidence interval 1.27-11.47).

CONCLUSIONS

Prodromal unstable angina is a strong predictor of infarct size and survival. Recognizing prodromal unstable angina is important for clinically assessing prognosis.

Long-term low-molecular-weight heparin (Fragmin) and/or early revascularization during instability in coronary artery disease (the FRISC II Study)

The Fragmin and/or Early Revascularisation during Instability in Coronary Artery Disease (FRISC II) trial will, in a prospective multicenter factorially randomized study, compare the efficacy of 3 months continuation of subcutaneous treatment with the low-molecular-weight heparin dalteparin (Fragmin) with that of placebo and will also compare a direct invasive strategy with a stepwise selective approach with regard to the utilization of coronary angiography and revascularization in patients with unstable coronary artery disease. The primary endpoints are death or myocardial infarction after 3 and 6 months respectively. Secondary endpoints are the same events after 12-24 months and also cardiac symptoms, exercise capacity, and/or signs of myocardial ischemia, readmission, and costs. Analyses will also be made of subgroups based on inclusion diagnosis, initial elevation of biochemical markers of myocardial damage, elevation of fibrinogen or C-reactive protein, signs of ischemia in electrocardiography at rest or at continuous 24-hour ischemia monitoring, and left ventricular function at echocardiography. Altogether, 3,100 patients will be recruited in 65-70 Scandinavian centers. Completion of follow-up is anticipated in the second half of 1998. The FRISC II study will further elucidate new alternatives for antithrombotic, invasive, and individually tailored treatment of unstable coronary syndromes.