Abstract
OBJECTIVES: The myocardial recovery time following on-pump cardiac surgery remains uncertain. Global peak longitudinal strain is a sensitive measure of endocardial function which is most susceptible to ischaemia. We aimed to evaluate changes in global peak longitudinal strain up to 6 months after surgery and to compare initial changes with alterations in troponin T. Secondarily, we aimed to describe perioperative changes in strain of the inter-ventricular septum when compared with reference segments. METHODS: Patients scheduled for coronary bypass, aortic valve replacement or combination procedures were enrolled. Echocardiography was performed on the day before surgery, the day after surgery, 4 days after surgery, 30 days after surgery and 6 months after surgery. Troponin T was measured 3, 16 and 24 h following procedure. RESULTS: Forty patients were enrolled and one was later excluded. Global peak longitudinal strain decreased from -14.5 ± 3.33% preoperatively to -9.98 ± 3.09% and -10.57 ± 3.16% on the first and fourth postoperative day, respectively. Global strain was still reduced on the 30th postoperative day, but had returned to preoperative values 6 months after surgery. Absolute values and relative changes in global strain did not correlate with postoperative peak troponin T measurements. Strain of the inter-ventricular septum was unaffected by surgery as opposed to reference segments, although septal displacement in the longitudinal direction decreased from 12.0 ± 3.75 mm preoperatively to 3.58 ± 4.22 mm 4 days after surgery. CONCLUSIONS: Global peak longitudinal strain was reduced for at least 30 days after on-pump cardiac surgery and seems to represent a more sensitive marker of myocardial function than ejection fraction. The decrease in global strain was not reflected in troponin T measurements. The visual, echocardiographic impression of septal dysfunction may be a translational phenomenon, as septal strain was unaffected by surgery.