CHICAGO — Sometimes a woman's heart can be too strong for her own good.
Data from the Global Registry of Acute Coronary Events (GRACE) indicate that elderly women with supernormal left ventricular systolic function as defined by an ejection fraction (EF) greater than 65% at the time they present with an acute coronary syndrome (ACS) have a twofold greater mortality risk than those presenting with a normal EF, Dr. Fadi A. Saab reported at the annual scientific sessions of the American Heart Association.
The highest mortality of all in the GRACE analysis was seen in elderly women with an EF below 55%, as would be expected. Depressed left ventricular systolic function complicating ACS is well established as the most powerful predictor of poor outcome, both during acute hospitalization and at 6 months.
However, the elevated risk associated with supernormal EFs came as a surprise to the investigators. A plot of in-hospital mortality against EF deciles in the more than 5,100 women over age 65 with ACS in GRACE describes a J-shaped curve with a nadir at an EF of 60%–69%. “We believe this is the first time this J-shaped association has been described,” noted Dr. Saab of the University of Michigan, Ann Arbor.
GRACE is an ongoing Sanofi-Aventis-sponsored observational study at 112 hospitals in 14 countries. An EF below 55% was present in 2,987 elderly female ACS patients in GRACE, a normal EF of 55%–65% in 1,483, and a supernormal EF in 657.
In a multivariate logistic regression analysis adjusted for age, medical history, Killip class at presentation, in-hospital complications such as heart failure or atrial fibrillation, in-hospital management, and medical therapies, an EF greater than 65% was an independent predictor of poor outcomes. It was linked to a 2.4-fold greater risk of in-hospital mortality than in patients with a normal EF, a 2.0-fold greater 6-month mortality, and a 2.5-fold increased risk of cardiac arrest/ventricular fibrillation.
Dr. Saab said one possible explanation for the observed association between supernormal EF and poor outcomes is that elderly women with a hypertrophic heart and a very high EF may be particularly susceptible to oxygen supply-mediated myocardial ischemia, with resultant QT prolongation and an increase in serious arrhythmias, although he was quick to add that this is speculation.
Session cochair Dr. Galen S. Wagner noted that the GRACE investigators haven't looked at elderly male ACS patients with supernormal EFs. “We know that elderly women do badly if their hearts are too strong, but we really don't know what it means when elderly men have hearts that are too strong,” observed Dr. Wagner of Duke University, Durham, N.C.
'This is the first time this J-shaped association [between mortality and EF deciles]has been described.' DR. SAAB