March 15, 2015 – Researchers found no association between GLS and New York Heart Association symptom class, functional capacity, or quality-of-life score.
Left ventricular global longitudinal strain (LVGLS) is common in patients with heart failure with preserved ejection fraction (HFpEF), and is associated with biomarkers of wall stress and collagen synthesis as well as severity of diastolic dysfunction, according to a study by DCRI researchers.
However, the researchers found no association between GLS and New York Heart Association symptom class, functional capacity, or quality-of-life score.
These findings were presented Sunday in a poster session at the Scientific Sessions of the American College of Cardiology in San Diego, California. The study was conducted by the DCRI’s Adam DeVore, MD (pictured); Steven McNulty, MS; Kevin Anstrom, PhD; Adrian Hernandez, MD, MHS; Eric Velazquez, MD; and colleagues from Duke and other institutions.
HFpEF is a common condition, affecting approximately 2.5 million Americans, and treatment options are limited. Earlier research has suggested an association between LVGLS and HFpEF, but the nature and extent of that association has not been made clear until now.
In this study, the researchers sought to determine the prevalence of impaired LVGLS in HFpEF patients and assess the association of impaired LVGLS and other patient characteristics. To do so, DeVore and his colleagues used data from the Phosphodiesterase-5 Inhibition to Improve Clinical Status and Exercise Capacity in Diastolic Heart Failure (RELAX) trial. That trial was a double-blinded, placebo-controlled, randomized trial of chronic sildenafil therapy in patients with diastolic heart failure.
Patients enrolled in RELAX had a left ventricular ejection fraction of greater than 50 percent and previous evidence of HF (such as prior HF hospitalization or chronic loop diuretic use for HF and left atrial enlargement). All patients enrolled in the RELAX trial received an echocardiogram at baseline and again at 24 weeks. These echocardiograms allowed researchers to determine GLS in 187 of the original RELAX patients. Echocardiograms were evaluated by the Heart Failure Network Core Lab at the Mayo Clinic with additional strain analyses performed in the Duke Echocardiography Lab.
DeVore and his colleagues found that impaired LVGLS was present in 65 percent of the study population. Patients with the worst LVGLS had the highest N-terminal pro-B-type natriuretic peptide (NT-proBNP), which is associated with increased left wall stress. The researchers also found an association with increased fibrosis as measured by a biomarker of collagen synthesis.
Contrary to their expectations, however, the researchers discovered no association between impaired LVGLS and New York Heart Association symptom class, functional capacity, or cardiopulmonary exercise test or quality-of-life scores. The researchers noted, however, that their study may have lacked sufficient power to detect any such associations if they exist.
Also, symptoms and functional capacity may be better gauged by assessments conducted during exercise than by assessments conducted in patients at rest. Finally, decreased quality of life and functional capabilities in HFpEF patients may be linked with comorbid conditions rather than the condition itself. Further study is needed, they concluded.