Re-evaluate hs-cTnT cutoffs for MI type 5: study

Postoperative levels of high-sensitivity cardiac troponin T (hs-cTnT) often surpass defined cut-off values for myocardial infarction type 5 (MI-5; also known as peri-procedural MI), indicating the need to reassess current definitions, a recent study has found.

“Various definitions of MI-5 after coronary artery bypass grafting (CABG) have been proposed using different biomarkers and different and arbitrary cut-off values. This meta-analysis aims to determine the expected release of hs-cTnT after CABG in general and after uncomplicated surgery and off-pump CABG in particular,” the researchers said.

Fifteen studies (n=2,646) were ultimately included in the analysis and contributed 23 separate study arms reporting postoperative hs-cTnT values. The researchers found that peak concentrations were reached 6–8 hours after surgery, yielding a mean of 628 ng/L (95 percent confidence interval [CI], 400-856), which was roughly equal to 45-times the upper reference limit (URL).

Mean levels dropped gradually thereafter but remained high above the normal even >48 hours after the operation, with a mean hs-cTnT concentration of 192 ng/L.

According to the researchers, their findings suggested that using the latest universal definition of MI-4, which suggests an hs-cTnT cutoff value 10-times the URL, was highly conservative, as patients tended to exceed this limit within hours of the procedure.

“Furthermore, an essential difference in hs-cTnT release following on-pump vs off-pump CABG was found, implying the need for different cut-off values for different surgical strategies,” they added.