Usefulness of postoperative high-sensitive troponin T measurement and
implications for defining type 5 infarction
Abstract
Background and aim of the study Guidelines on myocardial
revascularization indicate for type V myocardial infarction (MI) that
postoperative troponin elevations need not be exclusively ischemic but
may also be caused by direct epicardial injury. Additional complexity
arises from the introduction of high-sensitive troponin markers. The
present study attempts to contribute to the understanding of
postoperative high-sensitive cardiac troponin T (hs-cTnT) increase.
Methods Type of surgery, potential factors affecting the postoperative
hs-cTnT increase, and possible thresholds indicative of type V MI were
analyzed. Results Among 400 included patients, 2.8% had
intervention-related ischemia analogous to the type V MI definition.
Receiver-operating characteristics confirmed good discriminatory power
for hs-cTnT and creatine kinase myocardial band (CK-MB), with ischemia
indicating thresholds for hs-cTnT (1705.5 ng/l) and for CK-MB (113 U/l).
The median postoperative hs-cTnT/CK-MB increase differed significantly
depending on the type of surgery, with the highest increase after mitral
valve and the lowest after off-pump coronary surgery. Regression
analysis confirmed Maze procedure (p<0.001), cardiopulmonary
bypass time (p=0.03), emergency indications (p= 0.01) and blood
transfusion (p=0.02) as significant factors associated with hs-cTnT
increase. In contrast, CK-MB increase was also associated with mortality
(p=0.002). Intra-pericardial defibrillation was the only
ischemia-independent factor additionally associated with proposed
thresholds (p<0.001). Conclusions The present results confirm
the influence of the type of surgery and other intervention-related
parameters on the postoperative hs-cTnT increase. Type V MI-indicating
thresholds may require reassessment, especially using high-sensitive
markers.