Heart failure (HF) patients who experience moderate functional mitral regurgitation (FMR) for at least six months after cardiac resynchronization therapy (CRT) are at an increased risk for death, researchers suggest in a study published this week.
The paper, published in the American Journal of Cardiology, analyzed 1,313 HF patients who were treated with CRT in an effort to establish what kind of impact existing mitral regurgitation might have on how patients respond to therapy. FMR is common in heart failure patients, corresponding author Jeroen J. Bax, MD, PhD, and co-authors wrote, affecting on average more than half of those with cardiomyopathies, but it’s unknown how it can influence CRT outcomes.
“Moderate to severe FMR portends a poor prognosis, increasing heart failure hospitalizations and death,” Bax, of the Heart Lung Center at Leiden University Medical Center in Leiden, the Netherlands, and colleagues wrote. “FMR may reduce, remain stable or worsen after CRT, which may impact prognosis.”
The study’s patients, 59 percent of whom presented with ischemic heart disease, all underwent CRT and were divided into four groups of FMR based on their progress six months post-therapy. Patients either had no FMR or mild FMR at baseline that remained unchanged at six months; no or mild FMR that transitioned to moderate or severe FMR at six months; moderate to severe FMR that improved to no or mild FMR; or moderate to severe FMR that remained unchanged at the six-month mark.
The majority of patients—51 percent—fell into the first category, with more mild baseline FMR that remained unchanged over time. Twenty-six percent had moderate or severe FMR that also remained unchanged, while patients whose FMR worsened or improved made up 6 percent and 18 percent of the pool, respectively.
“Findings from our large-scale study support the fact that FMR response to CRT during the first six months is an important predictor of long-term survival, and provide new insights to this relationship,” Bax et al. said.
They wrote moderate to severe FMR at baseline that remained unchanged six months after CRT was independently associated with all-cause mortality in heart failure patients—a link that remained solid even after adjusting for variables known to impact HF mortality, like the LV remodeling response to CRT.
“Although FMR and LV volumetric response to CRT are intertwined, the fact that a reduction in FMR was an independent predictor of survival after accounting for LV reverse remodeling demonstrates that the FMR reduction is not merely a reflection of the volumetric response of the LV, but contributes uniquely to long-term survival,” the authors wrote. “The results of the present study are clinically relevant as they emphasize the unmet need for heart failure patients in whom FMR persists or worsens after CRT.”