Speckle tracking echocardiography in patients with septic shock: a case control study (SPECKSS)

Abstract

Background: Sepsis-induced myocardial dysfunction is a well-recognized condition and confers worse outcomes in septic patients. 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. We investigate the measurement of myocardial strain by speckle tracking echocardiography for the diagnosis of sepsis-induced myocardial dysfunction.

Methods: This is a case-control study at a university-affiliated medical intensive care unit. Consecutive adult medical patients admitted with a diagnosis of septic shock were included. Patients with other causes of myocardial dysfunction were excluded. They were compared to age-matched, gender-matched, and cardiovascular risk-factor-matched controls, who were admitted to hospital for sepsis but did not develop septic shock. Transthoracic echocardiography was performed on all patients within 24 hours of diagnosis, and a reassessment echocardiogram was performed in the study group of patients upon recovery.

Results: Patients with septic shock (n = 33) (study group) and 29 matched patients with sepsis but no septic shock (control group) were recruited. The mean sequential organ failure assessment (SOFA) score for the study and control groups were 10.2 and 1.6, respectively (P < 0.001). In patients with septic shock, the mean arterial pressure was lower (76 mmHg vs 82 mmHg, P = 0.032), and the heart rate was higher (99 bpm vs 86 bpm, P = 0.008). The cardiac output (5.9 L/min vs 5.5 L/min, P = 0.401) and systemic vascular resistance (1090 dynes•sec/cm(5) vs 1194 dynes•sec/cm(5), P = 0.303) were similar. The study group had a greater degree of myocardial dysfunction measured by global longitudinal strain (GLS) (-14.5 % vs -18.3 %, P <0.001), and the myocardial strain differed upon diagnosis and recovery (-14.5 % vs -16.0 %, P = 0.010). Conventional echocardiographic measurements such as LVEF (59 % in the study group vs 61 % in the control group, P = 0.169) did not differ between the two groups.

Conclusion: Speckle tracking echocardiography can detect significant left ventricular impairment in patients with septic shock, which was not otherwise detectable by conventional echocardiography. The reversible nature of myocardial dysfunction in sepsis was also demonstrable. This echocardiographic technique is useful in the diagnosis and monitoring of sepsis-induced myocardial dysfunction.

Keywords: Global longitudinal strain; Sepsis; Sepsis-induced myocardial dysfunction; Septic cardiomyopathy; Septic shock; Speckle tracking echocardiography; Speckle tracking imaging; Strain.

Fig. 1

Flow diagram of the study. There were 16 patients excluded due to active cardiac conditions, including 4 patients with tachyarrhythmia, 4 patients on veno-arterial extracorporeal membrane oxygenation support, 3 patients with takotsubo cardiomyopathy, 2 patients were post-resuscitation for cardiac arrest, and 1 patient each with ST elevation myocardial infarction, myocarditis, and pericardial effusion. There were 13 patients excluded based on preexisting cardiac abnormalities, including 5 patients with ischemic cardiomyopathy, 3 patients with dilated cardiomyopathy, 2 with severe aortic stenosis, and 1 patient each with thyrotoxic heart disease, cardiac amyloidosis, and congenital heart disease

Fig. 2

Standard echocardiographic indices of left ventricular function. Left ventricular ejection fraction (LVEF): mean 59 % vs 61 %, P = 0.169. Left ventricular index of myocardial performance (LIMP): mean 0.25 vs 0.22, P = 0.319

Fig. 3

Left ventricular global longitudinal strain in the study and control groups at diagnosis of sepsis. Left ventricular global longitudinal peak systolic strain (LV GLS): mean –14.5 % vs –18.3 %, P < 0.001