Simple risk score model could help with weaning patients from mechanical circulatory support

Patients with severe heart failure or cardiogenic shock often need mechanical circulatory support (MCS) devices but deciding when to safely wean them off remains a challenge. Researchers from Shinshu University developed a simple risk score model using readily measurable health indicators to predict successful MCS weaning. This study analyzed data from 114 patients and found that the new scoring method can help doctors in making better decisions about weaning, promising improved patient outcomes.

Patients with severe heart failure or cardiogenic shock often require assistance from MCS devices such as venoarterial extracorporeal membrane oxygenation (VA-ECMO) or the IMPELLA heart pump. These devices help maintain blood flow to vital organs when the heart is too weak to do so on its own.

A critical aspect of the recovery process for such patients is determining when their heart is strong enough to function independently, so that external support can be gradually reduced, or they can be weaned off these devices. While several factors have been identified to guide the process of weaning patients off MCS, there is still a lack of standardized protocols or guidelines for doing so.

Now, however, instead of relying on complicated and invasive tests to assess heart function, researchers from Shinshu University School of Medicine, Japan, sought to develop a simple and safe method that would be feasible to implement for most hospitals. In their study published in the Journal of Cardiac Failure on August 13, 2024, the research team, led by Clinical Fellow Sho Suzuki along with researchers Hirohiko Motoki and Koichiro Kuwahara, propose a straightforward risk score to predict weaning of patients with cardiogenic shock off MCS.

Elaborating further about their study, Dr. Suzuki says, “We propose a score model that can accurately predict successful weaning from MCS in patients with cardiogenic shock. Interestingly, this score can be used to make bedside predictions about weaning, considering advanced therapy, or withdrawing the patient from care.”

Currently, doctors evaluate whether a patient can be successfully weaned off MCS by monitoring key health indicators, such as blood pressure, cardiac output, and left ventricular ejection fraction (LVEF), which measure how well the heart pumps blood. These parameters help determine if the heart is strong enough to function independently without assistance.

Dr. Suzuki and his team utilized these metrics from real-world clinical data to develop a risk score for predicting successful weaning from MCS. The researchers conducted a retrospective single-center cohort study by analyzing past data taken from 114 patients with cardiogenic shock. These patients received treatment with VA-ECMO or the IMPELLA heart pump between January 2013 and June 2023.

They examined patient data and outcomes related to weaning decisions made by a multidisciplinary heart team, which included cardiologists and cardiovascular surgeons. A patient was considered successfully weaned from MCS if the device was removed (or decannulation was performed) without requiring re-implantation and the patient survived until hospital discharge.

Out of the total cohort, 86 patients underwent the weaning procedure and 55 were successfully weaned off MCS. Those patients for whom weaning was not performed were found to have a higher rate of acute myocardial infarction (AMI) as well as poorer health indicators. They had lower average blood pressure (71 mm Hg) compared to those who succeeded (85 mm Hg), lower pulse pressure (38 ± 20 mm Hg versus 50 ± 19 mm Hg), and weaker heart function (30% versus 40% LVEF). They also had higher levels of lactate in their blood (11 mg/dL versus 9 mg/dL) and longer QRS duration (106 ms vs. 92 ms), indicating slower electrical activity in the heart’s ventricles.

Using these variables (AMI, mean blood pressure, lactate, QRS duration, and LVEF), the researchers developed two risk score formulas: a general weaning score and a simplified version.

The simplified version or the simple MCS weaning score categorizes patients into five groups based on success rates, by adding up the points associated with each risk factor. A score of 0 or 1 indicates the absence of risk factors, corresponding to a 100% success rate; 2 points reflect two risk factors, with an 81% success rate; 3 points indicate three risk factors with a 63% success rate; 4 points correspond to an 11% success rate; and 5 points indicate a 0% success rate. The health indicators used in the formula for arriving at this score are easy to measure with standard medical equipment, making the risk-scoring method practical and accessible for most hospitals.

“We are looking forward to further research on such non-invasive methods for weaning patients and hope to establish a prediction model that successfully predicts weaning without the need for hemodynamic assessments,” says Suzuki.