Functional Mitral Regurgitation Combined with Increased Early Diastolic Transmitral Velocity to Early Mitral Annulus Diastolic Velocity Ratio is Associated with a Poor Prognosis in Patients with Shock
Shock is a critical condition characterized by inadequate tissue perfusion and oxygenation, leading to high morbidity and mortality, particularly in intensive care unit (ICU) settings. Among the various complications associated with shock, functional mitral regurgitation (FMR) and elevated left atrial (LA) pressure are increasingly recognized as significant contributors to poor outcomes. This study investigates the prognostic impact of FMR and the early diastolic transmitral velocity to early mitral annulus diastolic velocity ratio (E/e’) in patients with shock, providing valuable insights into the pathophysiology and management of this complex condition.
Mitral regurgitation (MR) is a common valvular disorder characterized by the retrograde flow of blood from the left ventricle (LV) into the left atrium during systole. Functional mitral regurgitation (FMR), in particular, occurs in the absence of structural abnormalities in the mitral valve leaflets and is associated with LV remodeling and dysfunction. FMR is prevalent in patients with heart failure and is linked to increased morbidity and mortality. Elevated LA pressure, often resulting from FMR, can exacerbate pulmonary congestion and impair cardiac output, creating a vicious cycle that worsens the prognosis of critically ill patients.
The study retrospectively analyzed 130 consecutive patients with shock who underwent transthoracic echocardiography (TTE) within six hours of shock onset. The patients were screened from a larger cohort of 175 patients admitted to the hospital between April 2016 and June 2017. The inclusion criteria were age ≥ 18 years, hypotension (systolic arterial pressure < 90 mmHg, mean arterial pressure 40 mmHg from baseline), arterial lactate concentration > 2 mmol/L, and urine output < 0.5 mL/kg/h. Exclusion criteria included age < 18 years, pregnancy, and refusal to participate by the patient or their family.
Critical care ultrasound (CCUS) examinations were performed by board-certified physicians with extensive experience in CCUS. The evaluations included two-dimensional, M-mode, and Doppler echocardiography, as well as tissue Doppler imaging. The presence of FMR was identified using Doppler color flow imaging, and LA pressure was assessed using the E/e’ ratio, with a cutoff value of ≥ 14 indicating elevated LA pressure. Lung ultrasound (LUS) was also performed to evaluate lung aeration using an eight-zone examination, with each zone scored based on the severity of lung pathology.
The study population had a mean age of 57.4 years, with 77 males and 53 females. The mean heart rate was 115.6 beats/min, and the mean arterial pressure was 80.1 mmHg. The median lactate concentration was 3.5 mmol/L, and the average Acute Physiology and Chronic Health Evaluation (APACHE) II score was 23.9. Among the patients, 99.2% were mechanically ventilated, with a median ventilation time of 162 hours. The primary causes of shock were distributive shock (62.3%), hypovolemic shock (30.0%), cardiogenic shock (6.2%), and obstructive shock (1.5%).
Of the 130 patients, 44 (33.8%) had FMR, and 15 (11.5%) had an elevated E/e’ ratio. Patients with FMR were older and had higher lactate concentrations, higher APACHE II scores, and higher E/e’ values compared to those without FMR. Similarly, patients with an elevated E/e’ ratio were older and had higher lactate concentrations and higher 28-day mortality rates compared to those with a normal E/e’ ratio.
Multivariate logistic regression analysis identified FMR and elevated E/e’ ratio as independent risk factors for 28-day mortality. The odds ratios for FMR and E/e’ were 0.344 and 1.156, respectively. Additionally, lung ultrasound score (LUSS) and lactate concentration were also independently associated with 28-day mortality, with odds ratios of 1.073 and 1.134, respectively.
Kaplan-Meier survival analysis revealed significant differences in survival between patients with and without FMR, as well as between those with elevated and normal E/e’ ratios. Patients were divided into four groups based on the presence of FMR and E/e’ ratio: Group 1 (E/e’ < 14 without FMR), Group 2 (E/e’ < 14 with FMR), Group 3 (E/e’ ≥ 14 without FMR), and Group 4 (E/e’ ≥ 14 with FMR). The survival analysis showed that Group 1 had the highest survival rate, while Group 4 had the lowest survival rate. The 28-day mortality rates for the four groups were 33.8%, 57.9%, 77.8%, and 100.0%, respectively.
The study highlights the significant impact of FMR and elevated E/e’ ratio on the prognosis of patients with shock. FMR, which is prevalent in critically ill patients, leads to increased LA pressure and pulmonary congestion, further exacerbating the hemodynamic instability associated with shock. Elevated E/e’ ratio, a marker of increased LA pressure, is also independently associated with higher mortality rates. The combination of FMR and elevated E/e’ ratio results in the worst prognosis, underscoring the need for early detection and intervention in these patients.
The findings suggest that monitoring for FMR and elevated E/e’ ratio in patients with shock, particularly in elderly patients, is crucial for improving outcomes. Interventions aimed at reducing LA pressure and optimizing hemodynamic parameters may help break the vicious cycle of FMR and elevated LA pressure, thereby improving the prognosis of these critically ill patients.
In conclusion, this study provides valuable insights into the prognostic impact of FMR and elevated E/e’ ratio in patients with shock. The presence of FMR and elevated E/e’ ratio are independent risk factors for 28-day mortality, and their combination is associated with the worst outcomes. Early detection and targeted interventions to reduce LA pressure and optimize hemodynamics may improve the prognosis of patients with shock. Further large-scale, multicenter, and prospective studies are needed to confirm these findings and explore potential therapeutic strategies.
doi.org/10.1097/CM9.0000000000001756
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