MRI scans evaluate heart failure risk—no invasive catheterization required
Mixed venous oxygen saturation (SvO2) measured with an invasive right heart catheterization offers a key biomarker to confirm heart failure, but researchers have now shown that cardiac MRI scans offer a noninvasive way to capture these measurements. Their findings were published in full in JACC: Advances.[1]
A group of specialists from Newcastle University, the University of Leeds and the University of East Anglia found they could use cardiovascular magnetic resonance (CMR) T2 intracardiac blood pool data to create imaging-derived SvO2 (iSvO2) noninvasively.
"It is known that invasively measured mixed venous saturation of below 60% in patients with heart failure is a marker of adverse outcomes. Our findings have replicated this noninvasively with iSvO2 being predictive of a composite of heart failure hospitalization and death, even after adjustment for age, sex, left ventricular ejection fraction (LVEF), N-terminal pro-B-type natriuretic peptide (NT-proBNP), and NYHA functional class," lead author Adam K. McDiarmid, consultant cardiac transplant physician at Freeman Hospital, Newcastle Hospitals NHS Trust, and colleagues wrote in the study.
The group tested their iSvO2 modeling in a cohort of 30 using CMR T2 mapping and invasive right heart catheterization. They then tested the model in a validation cohort of 628 patients with recently diagnosed heart failure. Overall, they concluded that iSvO2 is an independent predictor of mortality and heart failure hospitalization.
Echocardiography is often used to assess LVEF for heart failure. However, the authors said it can be preserved in restrictive cardiomyopathies and it does not consistently predict outcomes across the broader heart failure population. Physiological measures such as cardiopulmonary exercise testing and right heart catheterization (RHC) are used in the advanced heart failure patients to help determine if more advanced therapies are needed. But the researchers in this study said SvO2 provides a measure of tissue oxygen extraction and is measured during RHC in the main pulmonary artery.
Low SvO2 in heart failure is caused by a reduction in cardiac output. This measure is typically used to monitor response to therapy in advanced heart failure and cardiogenic shock, but the added RHC can be uncomfortable for the patient. Also, as an invasive procedure, the RHC carries its own risk of complications.
"We have demonstrated that LV and RV blood pool T2 on CMR can be used to accurately derive pulmonary artery SvO2. When applied to a real-world heart failure registry, iSvO2 is a better predictor of outcome than either LVEF or NT-proBNP, and as such may offer an opportunity to derive important prognostic data with CMR that had only previously been possible invasively," the authors wrote.
Dave Fornell has covered healthcare for more than 17 years, with a focus in cardiology and radiology. Fornell is a 5-time winner of a Jesse H. Neal Award, the most prestigious editorial honors in the field of specialized journalism. The wins included best technical content, best use of social media and best COVID-19 coverage. Fornell was also a three-time Neal finalist for best range of work by a single author. He produces more than 100 editorial videos each year, most of them interviews with key opinion leaders in medicine. He also writes technical articles, covers key trends, conducts video hospital site visits, and is very involved with social media. E-mail: [email protected]