CK-MB prognostic value limited in PE
MedWire News: Raised creatine kinase-MB (CK-MB) isoenzyme is a strong predictor of death from pulmonary embolism (PE), but the low prevalence of high CK-MB levels in PE patients limits its value as a prognostic indicator, US research shows.
"Prognosis of stable patients with acute PE has been assessed with cardiac troponin I (cTnI) and right ventricular (RV) function or size," note Paul Stein (Michigan State University, East Lansing) and colleagues.
To investigate if CK-MB adds to the prognostic assessment of patients with PE, Stein and team retrospectively assessed in-hospital mortality rates among 392 stable PE patients (44% men) admitted to two Michigan Hospitals.
The researchers found that 29 (7.4%) patients had high CK-MB levels, 76 (19%) had high cTnI, and 128 (33%) had RV dilation.
The highest proportion of deaths occurred among the patients with high CK-MB, at 14% compared with 7.9% for high cTnI and 6.3% for RV dilation. But the small absolute numbers prevented the identification of any statistically significant differences.
High CK-MB and high cTnI provided added prognostic information to patients with RV dilation. Specifically, patients with RV dilation and high CK-MB had a higher mortality rate than those with RV dilation and high cTnI, with respective mortality rates of 21% and 13%.
The proportion of deaths due to PE was highest when all three markers were abnormal, at 29% (4 of 14).
Logistic regression showed that high CK-MB was the strongest predictor of mortality, as patients with high CK-MB were 7.1 times more likely to die that those with normal CK-MB.
Patients with high cTnI had a 5.0-fold greater likelihood of death than those with normal levels, while patients with RV dilation were 4.3 times more likely to die than those without RV dilation.
Writing in the American Journal of Cardiology, Stein and co-authors conclude that the relatively small proportion of patients with PE plus an abnormal CK-MB, "limits its value if used as the only indicator of prognosis."
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By Laura Dean