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FREQUENT DISTURBANCES FROM RESTLESS LEGS SYNDROME MAY INFLUENCE HEART HEALTH
Study Shows RLS Can Negatively Effect on Heart Structure, Function and Long-Term Heart Health
New Orleans, LA – Mounting evidence has shown that frequent sleep disturbances may predispose some people to heart conditions. New data demonstrates that people with Restless Legs Syndrome (RLS) – characterized by frequent and involuntary leg movement during sleep – have more thickening of their heart muscle, known as left ventricular hypertrophy (LVH), and those with severe LVH have more than two-fold risk of having any cardiac event or death, according to research presented today at the American College of Cardiology’s 60th Annual Scientific Session. ACC.11 is the premier cardiovascular medical meeting, bringing together cardiologists and cardiovascular specialists to further advances in cardiovascular medicine.
This study involved 584 patients with a clinical diagnosis of RLS who were referred to the sleep lab for an overnight sleep study. These patients were then divided into two groups based on the frequency of leg movement during sleep: 45 percent of patients had frequent leg movement (defined as Periodic Movement Index [PMI] >35/hr) and 55 percent had infrequent leg movement (PMI≤35/hr). Despite a similarly preserved left ventricular ejection fraction – an objective measure of heart function – people with frequent leg movement were above the normal range on all three parameters indicative of LVH, a known risk factor for adverse cardiovascular outcomes. They were also more likely to be older (65 vs. 61years old), male and had a higher incidence of coronary artery disease.
“We have known for a long time that left ventricular hypertrophy is a poor prognostic factor, and patients with LVH are at risk of more cardiac events,” said Arshad Jahangir, M.D., professor of medicine, Mayo Clinic, Arizona, and principal investigator of the study. “What is new about this study is that it appears Restless Legs Syndrome is another risk factor that may predispose patients to and lead to more complications of LVH.”
Patients with more marked LVH and atrial fibrillation (a common heart rhythm disorder) had significantly higher incidences of heart failure, recurrent hospitalizations and death over a mean 3-year follow-up. While patients with frequent leg movement were more likely to have atrial fibrillation (p <0.01), even among participants who did not have this heart rhythm disorder, those with severe LVH had more cardiac events. Severe LVH was evident in 37 percent of people with atrial fibrillation and 20 percent of those without, suggesting that underlying heart conditions, specifically electrical dysfunction, and RLS may somehow together lead to more cardiovascular problems.
At baseline, there were no significant differences in cardiovascular risk factors including high blood pressure, diabetes, high cholesterol, heart failure or kidney function problems among those with frequent vs. infrequent leg movement. Clinical and echocardiographic parameters were compared between both groups.
RLS is estimated to affect 12 million Americans and is more common in older age. It also accounts for one-third of insomnia cases. Within RLS, a majority of patients (80-90 percent) have Periodic Limb Movement Disorder, which is characterized by involuntary leg-jerking movements, sometimes throughout the night, resulting in disturbed sleep.
While the exact mechanism of RLS is not entirely understood, Jahangir explains that abnormalities in the brain’s signaling that control the sympathetic nervous system appear to play a role. Increases in heart rate and blood pressure have previously been reported in patients with RLS.
“Similar mechanisms may be contributing to LVH, but this needs to be confirmed,” Jahangir said. “With the aging population, the prevalence of cardiovascular disease, LVH and RLS is expected to increase and, as a result, the impact of RLS on cardiovascular morbidity and mortality may increase. Therefore, understanding these relationships becomes important in order to prevent progression of cardiovascular mechanical and electrical dysfunction.”
Jahangir and his team stress that the observations in this study need to be confirmed in a larger number of patients. In addition, future research should assess whether treatments for RLS can prevent LVH outcomes.
This study was funded by the National Heart, Lung, and Blood Institute and the Angel and Paul Harvey Cardiovascular Research Endowment to CardioGerontology Research Laboratory at Mayo Clinic Arizona.
Dr. Jahangir will be available to the media on Sunday, April 3 at 1:00 p.m. CDT in Room 338/339.
Dr. Mahek Mirza, a co-author on the study, will present “Fragmented Sleep Due to Frequent Leg Movement Is Associated with Left Ventricular Hypertrophy and Poor Cardiovascular Outcomes” on Monday, April 4 at 3:30 p.m. CDT in Hall F of the Ernest N. Morial Convention Center.
The American College of Cardiology (www.cardiosource.org) represents the majority of board certified cardiovascular care professionals through education, research, promotion, development and application of standards and guidelines – and to influence health care policy. ACC.11 is the largest cardiovascular meeting, bringing together cardiologists and cardiovascular specialists to share the newest discoveries in treatment and prevention, while helping the ACC achieve its mission to address and improve issues in cardiovascular medicine.