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Cardiac isoenzyme values after total joint arthroplasty
D K Wukich1, J J Callaghan, G M Graeber
1Orthopaedic Surgery Service, Walter Reed Army Medical Center, Washington, D.C. 20307.
Insights
Total joint arthroplasty can elevate creatine kinase-myocardial band (CK-MB) due to skeletal muscle injury. However, significant increases in CK-MB percentage or lactate dehydrogenase isoenzyme-1 to isoenzyme-2 ratio may indicate myocardial infarction.
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.
Abstract:
The purpose of this study was to prospectively determine what effect total joint arthroplasty had on the myocardial-associated isoenzymes of serum creatine kinase (CK-MB) and lactate dehydrogenase (LD-1:LD-2). Fifty patients treated with total joint arthroplasty of the hip or knee had isoenzyme determinations using automated spectrophotometry and agarose gel electrophoresis. Skeletal muscle injury associated with the trauma of surgery resulted in significant elevations of the absolute value of CK-MB; however, the percentage of CK-MB comprising total CK activity and LD-1:LD-2 did not rise significantly in patients who did not experience postoperative myocardial infarction. It is important to determine both serum CK-MB and LD-1:LD-2 in suspected postoperative myocardial infarction since false positive elevations of CK-MB can occur. Elevations of CK-MB exceeding 50 International Units/liter or 5% of the total CK activity combined with LD-1:LD-2 exceeding 1.0 should not be attributed to skeletal muscle injury alone following total joint arthroplasty of the hip or knee.