Cardiac isoenzyme values after total joint arthroplasty

Area of Science:

• Cardiology
• Orthopedic Surgery
• Biochemistry

Background:

• Total joint arthroplasty (TJA) is a common orthopedic procedure.
• Postoperative cardiac complications, including myocardial infarction (MI), are a concern in TJA patients.
• Serum isoenzymes of creatine kinase (CK-MB) and lactate dehydrogenase (LD-1:LD-2) are biomarkers for myocardial injury.

Purpose of the Study:

• To prospectively evaluate the impact of TJA on serum CK-MB and LD-1:LD-2 levels.
• To differentiate between skeletal muscle injury and myocardial injury following TJA.
• To establish criteria for diagnosing postoperative MI in TJA patients.

Main Methods:

• Prospective study of 50 patients undergoing hip or knee TJA.
• Measurement of serum CK-MB and LD-1:LD-2 using automated spectrophotometry and agarose gel electrophoresis.
• Correlation of isoenzyme levels with surgical trauma and postoperative cardiac events.

Main Results:

• Skeletal muscle injury from TJA caused significant absolute elevations in CK-MB.
• The percentage of CK-MB relative to total CK and the LD-1:LD-2 ratio did not significantly increase in patients without MI.
• False positive elevations of CK-MB can occur due to skeletal muscle injury.

Conclusions:

• Monitoring both absolute CK-MB and its percentage of total CK, along with LD-1:LD-2 ratio, is crucial for diagnosing postoperative MI after TJA.
• CK-MB elevations exceeding 50 IU/L or 5% of total CK, coupled with an LD-1:LD-2 ratio >1.0, suggest myocardial injury beyond skeletal muscle trauma.
• These findings aid in accurate diagnosis and management of suspected myocardial infarction in the TJA population.