Overview
The SHAPE study is a prospective, randomized study evaluating changes in cardiac function in adult patients undergoing cardiac surgery with cardiopulmonary bypass. The study focuses on how cardiac function changes during surgery and whether the depth of anesthesia may influence these changes.
Participants are randomly assigned to one of two levels of anesthesia depth, guided by the Bispectral Index (BIS). Cardiac function is assessed using transthoracic echocardiography, including myocardial deformation (strain) imaging and myocardial work measurements. Invasive hemodynamic measurements obtained during surgery are also recorded.
The primary objective is to assess the change in left ventricular global longitudinal strain (LV GLS) between two intraoperative time points: after induction of anesthesia and before cardiopulmonary bypass, and after separation from cardiopulmonary bypass. The study will also examine whether these changes differ according to the assigned depth of anesthesia and whether echocardiographic and hemodynamic measurements are associated with postoperative outcomes.
Participants will also undergo follow-up echocardiographic assessment at 3, 6, and 12 months after surgery to evaluate longer-term changes in cardiac function.
Description
The SHAPE study is a prospective, randomized, parallel-group, single-masked interventional study conducted in adult patients undergoing elective cardiac surgery with cardiopulmonary bypass. The study is designed to investigate perioperative changes in myocardial function and to assess the potential influence of anesthesia depth on these changes.
Participants are randomized in a 1:1 ratio to two Bispectral Index (BIS)-guided anesthesia strategies: a BIS target of 45-55, representing standard anesthesia depth, or a BIS target of 30-35, representing deeper anesthesia. Total intravenous anesthesia with propofol and remifentanil is adjusted by the treating anesthesiologist to maintain the assigned BIS range. The echocardiographic outcome assessor remains blinded to treatment allocation during image acquisition, offline echocardiographic analysis, and primary outcome assessment.
Cardiac function is evaluated using transthoracic echocardiography and speckle-tracking analysis. Measurements include left ventricular global longitudinal strain (LV GLS), myocardial work indices, and additional indices of left- and right-sided cardiac function. Invasive hemodynamic monitoring using a Swan-Ganz catheter provides measurements including pulmonary capillary wedge pressure, cardiac output, cardiac index, pulmonary artery pressure, and right atrial pressure.
The primary analysis evaluates the within-participant change in LV GLS between two predefined intraoperative time points: after induction of anesthesia and before initiation of cardiopulmonary bypass (T1), and after separation from cardiopulmonary bypass (T2). Secondary analyses will assess whether the magnitude of perioperative changes in LV GLS and myocardial work differs between the two randomized BIS groups and will explore associations between echocardiographic measurements, invasive hemodynamic parameters, and postoperative clinical outcomes.
Postoperative outcomes include low cardiac output syndrome, requirement for inotropic or vasopressor support, postoperative atrial fibrillation, duration of mechanical ventilation, and length of intensive care unit stay. Echocardiographic follow-up is performed at 3, 6, and 12 months after surgery to assess longer-term changes in cardiac function.
Eligibility
Inclusion Criteria:
- Adults aged 18 years or older, irrespective of sex.
- Scheduled to undergo elective cardiac surgery involving cardiopulmonary bypass (on-pump surgery).
- Anticipated adequate acoustic window for transthoracic echocardiography.
- Provision of written informed consent.
Exclusion Criteria:
- \- Emergency or unscheduled cardiac surgery.
- Cardiac surgery without cardiopulmonary bypass (off-pump surgery).
- Refusal or inability to provide written informed consent.
