Elevated CK-MB but Normal Total CK: Grounds for Concern?

The diagnosis of acute MI is partially dependent on elevated levels of creatine kinase-MB isoenzyme. Patients may present with chest pain and a normal total CK level but also have an elevated ratio of CK-MB to total MB. Do these patients have an adverse prognosis? Investigators from Massachusetts General Hospital in Boston followed 595 consecutive patients with chest pain who developed an elevated CK-MB to total MB ratio within 24 hours of hospitalization. Of these patients, 263 (44 percent) had normal total CK (155 with elevated absolute CK-MB levels of at least 7.5 ng/ml and 108 with normal CK-MB levels less than 7.5 ng/ml) and were categorized as "MB leak," 202 (34 percent) had non-ST elevation acute MI, and 130 (22 percent) had ST-eleva…