Closer examination of diastolic HF needed in era of better detection technology

Issue: August 2008

Although not as well understood as systolic heart failure, diastolic heart failure presents researchers and clinicians with a unique set of challenges.

“The previous notion that HF and low ejection fraction were synonymous is no longer an acceptable way of thinking about HF,” William C. Little, MD, chief of cardiology at Wake Forest University Baptist Medical Center, told Cardiology Today. “Unfortunately, HF with normal ejection fraction or HF without a reduced ejection fraction has only recently been recognized.”

With the advent of echocardiography and tissue Doppler imaging, practitioners have been able to distinguish between the different types of HF by evaluating the dynamics of LV filling.

“Echocardiography is the standard way to measure LV ejection fraction, and with Doppler and tissue Doppler, we can now look for diastolic dysfunction,” Little said. “Tissue Doppler is evolving as the best way to look for diastolic dysfunction.”

Since some form of diastolic dysfunction is present in nearly all HF patients, characterizing it becomes crucial. According to the AHA, about 5.3 million people in the United States were living with HF in 2005, with 284,365 deaths attributed to HF. Patients with a history of essential hypertension are most likely to develop both forms of HF, but diastolic HF is most prevalent among women aged older than 65 years.

“Part of the reason that it is more common in elderly women is that there are far more women over 80 years in the United States than there are men over 80 years,” Little said. “The second reason is that since women tend to be of shorter stature, this contributes to early arterial BP reflection from the periphery, which enhances systolic hypertension.”

Clinical research in diastolic HF

William C. Little, MD, has studied diastolic HF, which is not as well-defined as systolic HF.

Source: Creative Communications, WFUSM

Some estimates indicate that the prevalence of diastolic HF and the closely related condition of LV diastolic dysfunction comprise 30% to 50% of all HF cases in elderly patients. Results from several studies have also suggested that diastolic HF is associated with significant morbidity and mortality.

Researchers have attempted to document the extent to which diastolic HF can be treated in at least three clinical outcomes trials. The researchers from the Effect of Digoxin on Mortality and Morbidity in Patients with HF (DIG) trial reported that digoxin did not reduce overall HF mortality in patients with both diastolic and systolic HF. Results from the Effects of Candesartan in Patients with Chronic Heart Failure and Preserved Left Ventricular Ejection Fraction (CHARM-Preserved) trial suggested that the angiotensin receptor antagonist candesartan (Atacand, AstraZeneca) decreased hospitalizations of patients with HF and with an ejection fraction greater than 40%, but this was not considered statistically significant. The third was the Perindopril in Elderly People with Chronic HF (PEP-CHF) trial, in which the results suggested that the primary endpoint of HF hospitalization-free survival was negative.

Two advanced, randomized trials being conducted to evaluate the effects of certain therapies on diastolic HF are currently underway. The effects of irbesartan (Avapro; Bristol-Myers Squibb, Sanofi-Aventis) on diastolic HF are being examined in the Irbesartan in HF Patients with Preserved Systolic Function (I-PRESERVE) trial. The Treatment of Preserved Cardiac HF with Aldosterone Antagonist (TOP-CAT) trial is currently being conducted to examine the aldosterone antagonist spironolactone (Aldactone, Pharmacia & Upjohn) in patients with ejection fraction of at least 45%. Results of the I-PRESERVE trial are slated to be presented at the 2008 American Heart Association Scientific Sessions. The TOP-CAT trial will be ongoing for several more years.

Treating diastolic HF

Although the clinical evidence supporting effective treatment for diastolic HF is less prevalent than that for systolic HF, several therapeutic approaches are routinely taken. According to a review published in the Journal of the American Osteopathic Association, typical therapeutic strategies for diastolic HF include those targeted toward alleviating symptoms and controlling underlying conditions as well as “maintenance of euvolemia, rate control of atrial fibrillation and management of systemic arterial hypertension.” The lack of clinical data, however, has not stopped practitioners from trying to treat diastolic HF through known HF therapies.

“What has been proven to prevent the development of or to reduce the risk for development of diastolic HF is treating systolic hypertension, and that is evidence-based therapy,” Little said. “Other Level C recommendations are to treat systematic volume overload with diuretics and to treat the other contributing comorbidities that may be contributing to the HF, which include anemia, myocardial ischemia and diabetes.” – by Eric Raible

For more information:

J Am Osteopath Assoc. 2008;108:203-209.
N Engl J Med. 1997;336:525-533.
Lancet. 2003;362:777-781.
Eur Heart J. 2006;27:2338-2345.
J Card Fail. 2005;11:576-585.
http://www.americanheart.org/downloadable/heart/1200078608862HS_Stats%202008.final.pdf. Accessed July 10, 2008.