Interval Changes in Myocardial Performance Index Predict Outcome in Severe Sepsis

Objectives: Septic cardiomyopathy is a well-described consequence of septic shock and is associated with increased sepsis-related mortality. The myocardial performance index (MPI), a parameter derived from echocardiographic tissue Doppler measurements, allows for a more sensitive assessment of global cardiac function than do traditional metrics for cardiac function. The authors hypothesized that changes in left ventricular MPI in patients with severe sepsis would be associated with a higher 90-day mortality.

Design: Prospective, observational study.

Setting: Intensive care units of a tertiary medical center.

Participants: The study comprised 47 patients admitted with new diagnoses of severe sepsis or septic shock.

Interventions: All patients underwent transthoracic echocardiograms with assessment of MPI at enrollment and 24 hours later. Hemodynamic data and information on sepsis-related mortality were collected. In the primary analysis, the association between change in MPI from enrollment to 24 hours and sepsis-related 90-day mortality was assessed.

Measurements and main results: Of the 47 patients enrolled, 30 demonstrated an improvement in MPI from 0 to 24 hours ("improved" group), and MPI worsened in the remaining 17 patients ("worsened" group). Despite no significant differences in ejection fraction or severity of illness, the median MPI at enrollment in the "improved" group was higher than baseline values in the "worsened" group (p = 0.005). A worsening MPI over the 24-hour study interval was associated with increased mortality at 90 days (p = 0.04), which remained significant (hazard ratio 3.72; 95% confidence interval 1.12-12.41; p = 0.03) after adjusting for severity of illness (Acute Physiology and Chronic Health Evaluation II score), intravenous fluids, and vasopressor use.

Conclusions: In patients admitted to the intensive care unit with a diagnosis of severe sepsis or septic shock, a worsening MPI during the first 24 hours after intensive care unit admission was associated with higher 90-day mortality.