Focal myocardial injury following blunt chest trauma: a comparison of indium-111 antimyosin scintigraphy with other noninvasive methods.
The diagnosis of myocardial contusion is often difficult, as traditional methods such as serial electrocardiograms, cardiac enzyme (creatine kinase [CK-MB]) analysis, and echocardiography lack sensitivity and specificity. Recent reports have shown that 111In labelled antimyosin scanning has high sensitivity for detecting cardiac injury. However, no prior studies have been reported for antimyosin imaging with patients suspected of sustaining a cardiac contusion. Accordingly, 17 patients with severe multisystem trauma (intrathoracic vascular injury in eight patients, pneumothorax and pulmonary contusion in 13) underwent antimyosin scintigraphy, echocardiography, 12-lead electrocardiograms, and CK-MB determinations. Arrhythmias were noted in seven patients, four of whom died. All patients has elevated CK levels but CK-MB isoenzyme was greater than 4% in only three. Abnormal ST segments were noted in nine subjects, only one of whom had CK-MB elevation. Echocardiography revealed pericardial effusions in four patients but was technically suboptimal in 53% of the studies. Blinded interpretation of the antimyosin scans revealed only one with focal myocardial uptake; this same patient had the only discrete wall motion abnormality on the echocardiogram and also had ST depression with ectopy but normal CK-MB. Thus in patients with suspected myocardial contusion, echocardiography is frequently limited technically and the electrocardiogram and CK analysis appear to lack diagnostic accuracy. In contrast, monoclonal antimyosin imaging may be performed in patients with trauma without limitation and yields results that are concordant with echocardiograms. In patients with suspected myocardial contusion, focal antimyosin uptake is uncommon despite severe thoracic injury, which suggests that extensive myocardial necrosis is not the primary method of injury.