November 2, 2010 | Reed Miller

TheHeart.org

 

Montreal, QC – Assessing patients’ ability to withstand cardiac surgery may be as simple as timing them as they walk down the hospital corridor, according to results of a study in the November 9, 2010 issue of the Journal of the American College of Cardiology [1].

Studies consistently show that older patients benefit greatly from cardiac surgery, but that advanced age, usually defined as 70 years and older, is one of the strongest predictors of mortality and major morbidity with cardiac surgery. Unfortunately, the variety of risk-scoring systems designed to assess operative risk perform poorly in the elderly, overestimating mortality by as much as 250% in these patients, study authors Dr Jonathan Afilalo and colleagues (McGill University, Montreal, QC) explain.

“Accurately predicting outcomes in the elderly requires representation of the heterogeneity that exists in this population. This heterogeneity extends beyond differences in comorbid conditions to subclinical impairments in multiple interrelated systems,” the authors observe. “Accumulation of these subclinical impairments results in reduced homeostatic reserve and resiliency to stressors, a syndrome known as frailty.”

Previous studies have validated gait speed as a reliable measure of frailty and resiliency to the physiologic stress of surgery, so Afilalo et al studied the relationship of gait to complication rates in order to demonstrate the incremental prognostic value of slow gait speed beyond just showing that it is associated with complications.

They enrolled 131 patients 70 years or older (average was 76) scheduled for CABG and/or valve-replacement or repair at four centers. Each patient’s gait speed was tested in a 5-m walk down the corridor. Patients taking longer than six seconds were deemed to have a slow gait. Sixty patients in the study (46%) were classified as slow walkers before their cardiac surgery, and 30 (23%) experienced the primary composite end point of mortality or major morbidity after cardiac surgery. Slow gait was an independent predictor of the composite end point after adjustment for the Society of Thoracic Surgeons risk score (odds ratio 3.05, 95% 1.23-7.54). Slow walkers were more likely to be female (43% vs 25%, p=0.03) and diabetic (50% vs 28%, p=0.01).

This simple test of overall frailty may provide clinicians with a more comprehensive assessment of their patient’s risk, but “risk predictions should not be used to determine operability, because no level of predicted risk is unequivocally associated with adverse outcomes,” the authors explain. But patients with slow gait speed may benefit from specific interventions, such as intensive monitoring, early mobilization, planned discharge to a rehabilitation facility, or exercise training.

They also noted that patients undergoing surgical aortic-valve replacement who were identified as frail in the study appeared to be at particularly high risk of adverse outcomes, so the utility of frailty as a parameter to help decide between surgical or transcatheter aortic-valve replacement warrants further study, Afilalo et al conclude.

In an accompanying editorial [2], Dr Joseph Cleveland (University of Colorado, Denver) commends the simplicity of the gait test developed by Afilalo et al. “Their new screening tool, consisting of an observer, a stopwatch, and a well-lit hallway, is reproducible, and I believe will be extraordinarily cost-effective,” he predicts. “Most important, it replaces such subjective tests as the ‘eyeball test,’ which substantiated only that the judgment of clinicians varied greatly in selecting elderly patients for cardiac operations [2].”

Cleveland cautions, however, that this test does not identify which patients are at “profoundly increased risk” for surgical complications, and because the mean age of patients in the study was 75, it remains unclear if gait will be a good predictor of risk in patients 85 or 90. “A further study of the ‘oldest old’ is necessary,” Cleveland concludes.

Sources

1.Afilalo J, Eisenberg M, Morin JF, et al. Gait speed as an incremental predictor of mortality and major morbidity in elderly patients undergoing cardiac surgery. J Am Col Cardiol 2010; 56:1668-1676.

2.Cleveland J. Frailty, aging and cardiac surgery outcomes: The stopwatch tells the story. J Am Col Cardiol 2010; 56:1677-1678.

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