Investigators from the Institute for Clinical Evaluative Sciences (ICES), the Heart and Stroke Foundation of Ontario and the University of Toronto have identified a new common and deadly form of heart failure – “preserved” ejection fraction.
“This opens up a new field of investigation for us to address the number one chronic killer in Canada,” said Dr. Peter Liu, senior author of the study, and director of the Heart & Stroke Foundation/Richard Lewar Centre of Excellence at the University of Toronto.
Heart failure affects one in five Canadians over a lifetime and, once diagnosed, one in four will die within a year. Traditionally, doctors thought that heart failure results from a damaged heart pump (often from a previous heart attack), poorly controlled blood pressure, or a virus infection. As a result, the damaged heart will enlarge, and the proportion of blood pumped with each beat will diminish.
Doctors often rely on the decreased pumping ability, or low ejection fraction (EF), for the diagnosis of heart failure. EF is a measurement of the heart’s efficiency, which shows the percentage of blood pumped out of the heart with each heartbeat, and normally should be above 50%. However, the study team found that patients with this new form of heart failure have “normal” or “preserved” EF, and the heart does not enlarge, thus eluding the usual tools for diagnosis.
This new form of heart failure is very common, just as deadly, and is often not recognized as heart failure. Patients can come to the emergency department with severe weakness, shortness of breath, drowning with fluid build up in the lungs or in the legs, and doctors cannot be sure it is indeed a heart problem.
Investigators tracked 2,802 patients with heart failure admitted to 103 Ontario hospitals between April 1, 1999 and March 31, 2001. They examined the mortality and hospital re-admission rates between heart failure patients with “preserved” or “normal” EF and those with “reduced” EF.
The results showed that, surprisingly, the mortality rates for “preserved” EF heart failure patients were not significantly different from those with “reduced” EF at 30 days (5% vs. 7%) or at one year (22% vs. 26%). The one-year re-hospitalization rate was also similar between “reduced” EF and “preserved” EF patients (16% vs. 14%).
“This form of heart failure most commonly affects elderly women, and those with longstanding high blood pressure or diabetes. Since these conditions are becoming more common in our population, heart failure with preserved ejection fraction will continue to increase,” predicts Dr. Liu, who is also scientific director of the Institute of Circulatory and Respiratory Health at the Canadian Institutes of Health Research (CIHR). “Therefore, we must treat these important risk factors in order to prevent this type of deadly complication.”
“Our study has very important implications for clinicians who treat heart failure patients,” said study co-author Dr. Jack Tu, a senior scientist at ICES, and Canada Research Chair in Health Services Research at the University of Toronto.
“It suggests that we need to treat patients with heart failure and preserved ejection fraction as aggressively as we treat those with reduced ejection fraction. We also need to develop new treatments for heart failure patients with preserved ejection fraction, as these patients have historically been excluded from most clinical trials of new heart failure therapies.”
The study, “Outcome of heart failure with preserved ejection fraction in a population-based study”, is published in the July 20, 2006 issue of the New England Journal of Medicine.
Author affiliations: ICES (Drs. Tu, Lee, Austin, Fang, and Mr. Gong); Heart and Stroke/Richard Lewar Centre of Excellence, University of Toronto and Division of Cardiology, Toronto General Hospital, University Health Network (Drs. Bhatia, Tu, Lee, Haouzi, and Liu); National Heart, Lung, and Blood Institute Framingham Heart Study (Dr. Lee); Division of General Internal Medicine, Sunnybrook Health Sciences Centre, University of Toronto (Drs. Bhatia and Tu).
The Heart & Stroke Foundation/Richard Lewar Centre of Excellence is the Cardiovascular Research Centre funded jointly by the Heart & Stroke Foundation of Ontario, the Lewar Family and the University of Toronto. The Centre coordinates interdisciplinary research at the University of Toronto based on excellence, innovation and collaboration.
The Heart and Stroke Foundation (www.heartandstroke.ca) is a leading funder of heart and stroke research in Canada. Our mission is to improve the health of Canadians by preventing and reducing disability and death from heart disease and stroke through research, health promotion and advocacy.
The Canadian Institutes of Health Research (CIHR) is the Government of Canada's agency for health research. CIHR's mission is to create new scientific knowledge and to catalyze its translation into improved health, more effective health services and products, and a strengthened Canadian health care system. Composed of 13 Institutes, CIHR provides leadership and support to more than 10,000 health researchers and trainees across Canada. http://www.cihr-irsc.gc.ca. The CIHR Institute of Circulatory and Respiratory Health is devoted to funding research and researchers focused on etiology, mechanisms, prevention, detection, treatment, rehabilitation, and palliation of diseases of heart, lung, blood vessel (including stroke), blood, sleep, and critical care.
ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of health care issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting health care needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy.
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