ANN ARBOR, MICH—Many patients admitted to the medical intensive care unit (MICU) for noncardiac illness have underlying cardiac abnormalities, a recent study has found.[1] Although often not clinically apparent, these abnormalities can affect treatment decisions and patient outcomes.

“The results of the study were not completely unexpected,” said William F. Armstrong, MD. “[W]e knew that there was a significant prevalence of underlying cardiac disease, which was presumably not known at the time of admission to a [MICU].”

ONE THIRD OF PATIENTS AFFECTED

Dr. Armstrong, Professor of Medicine and Director of the Adult Echocardiography Laboratory at the University of Michigan in Ann Arbor, and colleagues evaluated 467 consecutive patients who were admitted to the MICU for noncardiac illness during a 12-month period. Within 18 hours of MICU admission, all patients underwent complete transthoracic two-dimensional echocardiographic and Doppler scanning.

All echocardiograms were interpreted by experienced cardiologists, who were blinded to the patients’ admitting diagnosis and history. When a critical abnormality was found, the test results were unblinded and the patient’s physician was informed. Physicians could also request unblinding when there was a clinical suspicion of underlying cardiac disease.

Cardiovascular abnormalities were present in 169 patients. A single cardiovascular abnormality was found in 103 patients, and two or more were found in 66. Notably, no clinical echocardiograms had been requested in 130 of these patients.

The most common abnormality detected was regional or global left ventricular dysfunction, followed by left ventricular hypertrophy, valvular insufficiency, and isolated chamber enlargement. In 52 patients, the abnormalities were sufficiently severe that the results were unblinded and the physicians notified.

In 67 patients, the physicians requested unblinding because of suspected cardiovascular disease. No cardiovascular abnormality was present in 28 of these patients.

Neither routine electrocardiograms nor chest films—or even the combination of the two—had better than 65% accuracy for detecting cardiovascular abnormalities. Furthermore, the likelihood of an abnormality could not be predicted based on the patient’s degree of illness; the lowest rates of abnormality were in the most severely ill patients.

The presence of cardiac abnormalities did not affect mortality in either the hospital or the MICU, but it did increase the length of stay.

WHY ARE ABNORMALITIES MISSED?

According to Dr. Armstrong, cardiac abnormalities may be missed in MICU patients because of the severity of illness at the time of admission. “This results in the … physician’s attention being directed to the most obvious illness, which often requires immediate [care] to stabilize the patient,” he said. In addition, he continued, “Many of the abnormalities that we noted are probably underappreciated … as having clinical relevance, and hence their diagnosis is not pursued.”

While many abnormalities, such as chamber enlargement, left ventricular dysfunction, and left ventricular hypertrophy, would not be expected to be found during a routine examination, other, more obvious, abnormalities also escaped detection. The current MICU admission procedure of clinical examination combined with routine chest film and electrocardiogram was not sufficient to detect the majority of cardiac abnormalities.

The investigators acknowledged the possibility that some cardiovascular abnormalities were not detected clinically because of the speed with which critical abnormalities were unblinded (this occurred within one hour of echocardiographic evaluation). However, they also noted that “the vast majority of patients with significant abnormalities were not unblinded within a time frame in which clinical suspicion should have become apparent.”

USING ECHOCARDIOGRAPHY

The authors of a commentary on the study remarked that the use of echocardiography in the MICU is hindered in many institutions by the unavailability of equipment and 24-hour access to echocardiography technicians or adequately trained physicians.[2]

They recommended training for ICU clinicians because echocardiography will likely be used increasingly in acute care settings. Physicians with extensive training in echocardiography have voiced their concern about potential errors—in both diagnosis and treatment—made by less thoroughly trained physicians.

“A major goal has to be a prospective suspicion of underlying cardiac disease, especially in an elderly population or in one with multiple risk factors for developing cardiac disease,” Dr. Armstrong asserted. “If properly employed by an appropriately trained individual, [echocardiography] can allow diagnosis of disease states responsible for the patient’s presentation and appropriately directed therapy—and, equally as important, remove significant cardiovascular disease from consideration,” he concluded.

—Gale Jurasek

References
1. Bossone E, DiGiovine B, Watts S, et al. Range and prevalence of cardiac abnormalities in patients hospitalized in a medical ICU. Chest. 2002;122:1370-1376.
2. Ketzler JT, McSweeney ME, Coursin DB. ICU echocardiography: should we use it in a heart beat? Chest. 2002;122:1121-1123.

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