Characterization of critically ill patients with septic shock and sepsis-associated cardiomyopathy using cardiovascular MRI

Abstract

Aims: Sepsis-induced cardiomyopathy is a major complication of septic shock and contributes to its high mortality. This pilot study investigated myocardial tissue differentiation in critically ill, sedated, and ventilated patients with septic shock using cardiovascular magnetic resonance (MR).

Methods and results: Fifteen patients with septic shock were prospectively recruited from the intensive care unit. Individuals received a cardiac MR scan (1.5 T) within 48 h after initial catecholamine peak and a transthoracic echocardiography at 48 and 96 h after cardiac MR. Left ventricular ejection fraction was assessed using both imaging modalities. During cardiac MR imaging, balanced steady-state free precession imaging was performed for evaluation of cardiac anatomy and function in long-axis and short-axis views. Native T1 maps (modified Look-Locker inversion recovery 5 s(3 s)3 s), T2 maps, and extracellular volume maps were acquired in mid-ventricular short axis and assessed for average plane values. Patients were given 0.2 mmol/kg of gadoteridol for extracellular volume quantification and late gadolinium enhancement imaging. Critical care physicians monitored sedated and ventilated patients during the scan with continuous invasive monitoring and realized breathholds through manual ventilation breaks. Laboratory analysis included high-sensitive troponine T and N terminal pro brain natriuretic peptide levels. Twelve individuals with complete datasets were available for analysis (age 59.5 ± 16.9 years; 6 female). Nine patients had impaired systolic function with left ventricular ejection fraction (LVEF) < 50% (39.8 ± 5.7%), and three individuals had preserved LVEF (66.9 ± 6.7%). Global longitudinal strain was impaired in both subgroups (LVEF impaired: 11.0 ± 1.8%; LVEF preserved: 16.0 ± 5.8%; P = 0.1). All patients with initially preserved LVEF died during hospital stay; in-hospital mortality with initially impaired LVEF was 11%. Upon echocardiographic follow-up, LVEF improved in all previously impaired patients at 48 (52.3 ± 9.0%, P = 0.06) and 96 h (54.9 ± 7.0%, P = 0.02). Patients with impaired systolic function had increased T2 times as compared with patients with preserved LVEF (60.8 ± 5.6 ms vs. 52.2 ± 2.8 ms; P = 0.02). Left ventricular GLS was decreased in all study individuals with impaired LVEF (11.0 ± 1.8%) and less impaired with preserved LVEF (16.0 ± 5.8%; P = 0.01). T1 mapping showed increased T1 times in patients with LVEF impairment as compared with patients with preserved LVEF (1093.9 ± 86.6 ms vs. 987.7 ± 69.3 ms; P = 0.03). Extracellular volume values were elevated in patients with LVEF impairment (27.9 ± 2.1%) as compared with patients with preserved LVEF (22.7 ± 1.9%; P < 0.01).

Conclusions: Septic cardiomyopathy with impaired LVEF reflects inflammatory cardiomyopathy. Takotsubo-like contractility patterns occur in some cases. Cardiac MR is safely feasible in critically ill, sedated, and ventilated patients using extensive monitoring and experienced staff.

Trial registration: retrospectively registered (ISRCTN85297773).

Keywords: CMR; Cardiac MR; Inflammation; Non-ischaemic cardiomyopathy; Sepsis; Septic cardiomyopathy; Septic shock.

Figure 1

Cardiovascular magnetic resonance setup for sedated and ventilated patients. (A) Positioning of MR‐safe ventilators, monitoring unit, and injections pumps. (B) During the scan, an intensive care specialist monitors patient continuously in the scanner room and receives commands for end‐expiratory breathhold via headphone.

Figure 2

LVEF development. Data points indicate LVEF of each individual at time of cardiovascular magnetic resonance scan (baseline), at 48 and at 96 h post‐cardiovascular magnetic resonance. Red data points indicate patients with LVEF impairment at baseline, and blue data points indicate patients with preserved LVEF at baseline. *P < 0.05 compared with baseline. LVEF, left ventricular ejection fraction.

Figure 3

Tissue differentiation with T1/T2/ECV mapping. Columns represent mean T1, T2, and ECV values measured in mid‐ventricular short axis for all study individuals with preserved (green) and impaired LVEF (red). P values indicate statistical significance. Mid‐ventricular short‐axis images of representative T2 maps, native T1 maps, and extracellular volume (ECV) maps of patient with and without LVEF impairment. LVEF, left ventricular ejection fraction.

Figure 4

Blood sample analysis. Data points represent mean high‐sensitivity cardiac troponin T (hsTnT) and N terminal pro brain natriuretic peptide (NT‐proBNP) levels at time of cardiovascular magnetic resonance scan (baseline) and 24, 48, 72, and 96 h post‐cardiovascular magnetic resonance. Red data points indicate individuals with LVEF impairment at baseline, and blue data points indicate individuals with preserved LVEF. *P < 0.05 compared with baseline in all subgroups. LVEF, left ventricular ejection fraction.