By Dr Yeung Pui Ning Pauline, QMH
Background: Sepsis-induced myocardial dysfunction is a well-recognized condition and confers worse outcomes in septic patients. However, the diagnostic criteria remain poorly described. Echocardiographic assessment by conventional parameters such as left ventricular ejection fraction (LVEF) is often affected by ongoing changes in preload and afterload conditions. Novel echocardiographic technologies such as speckle tracking echocardiography (STE) have evolved for direct assessment of the myocardial function. In this study, we investigate the measurement of myocardial strain by speckle tracking echocardiography for the diagnosis of sepsis-induced myocardial dysfunction.
Methods: This is a prospective, case-control study at a university-affiliated tertiary care adult medical intensive care unit. Consecutive patients admitted with a diagnosis of septic shock were included. Patients with other causes of myocardial dysfunction were excluded. They were compared to age-, gender-, and cardiovascular risk factors-matched controls, who were admitted to hospital for sepsis but did not develop septic shock. Conventional echocardiographic parameters, as well as speckle tracking imaging of myocardial function, were obtained within 24 hours of diagnosis. A second echocardiogram was performed in the study group of patients upon recovery.
Results: From January 2014 to January 2015, 33 patients with septic shock (study group) and 29 patients with sepsis but no septic shock (control group) were recruited. The baseline characteristics were similar. Conventional echocardiographic measurements, including LVEF (59.42% in the study group vs 61.28% in the control group, P=0.169) and fractional shortening (31.55% vs 32.86%, P=0.163) did not differ between the two groups. The hemodynamic profiles (cardiac index 3.48L/min/m2 vs 3.34L/min/m2, P=0.608) were not statistically different. The study group had a greater degree of myocardial dysfunction measured by left ventricular global longitudinal peak systolic strain (GLPSS) (‑14.5% vs ‑18.3%, P=<0.001, with a less negative value implying worse myocardial contractility). The myocardial strain measured at diagnosis and recovery was significantly different in the study group of patients (‑14.5% vs ‑16.0%, P=0.010).
Conclusion: This is a first study in the adult population to show that the use of speckle tracking echocardiography can detect significant myocardial impairment in patients with septic shock as compared to patients with sepsis but no septic shock, which was not otherwise detectable by conventional echocardiography. Further studies are warranted to investigate the clinical application of this echocardiographic technique in the diagnosis and prognostication of sepsis-induced myocardial dysfunction.