Clinical Investigations
The prognostic value of body mass index and standard exercise testing in male Veterans with congestive heart failure*

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Abstract

Objective: To evaluate the prognostic characteristics of body mass index (BMI) and standard exercise test variables in a consecutive series of patients with mild to moderate congestive heart failure (CHF) referred for standard exercise tests. Background: Controversy exists regarding the prognostic importance of BMI, etiology, and exercise test variables in patients with CHF. Methods: All patients referred for evaluation at two university-affiliated Veterans Affairs Medical Centers who underwent treadmill tests for clinical indications between 1987 and 2000 were determined to be dead or alive using the Social Security Death Index after a mean 6 years follow-up. Clinical and exercise test variables were collected prospectively according to standard definitions; testing and data management were performed in a standardized fashion using a computer-assisted protocol. Survival analysis was performed using all-cause mortality as the endpoint for follow-up. Results: A total of 522 patients with a history and clinical findings of CHF underwent exercise testing. Forty-two percent died during the follow-up period, for an average annual mortality of 6.7%. Cox proportional hazards model chose peak metabolic equivalents (METs), BMI, age, and ischemic etiology in rank order as independently and significantly associated with time to death. A score based on these variables classified patients into low (2% annual mortality), medium (5.2%), and high-risk groups (7% annual mortality). Conclusion: Standard exercise testing and BMI can be used to estimate prognosis in outpatients with heart failure. A score incorporating METs, BMI, age, and etiology efficiently stratified these patients. BMI was chosen by the survival analysis, confirming its surprising inverse relationship to prognosis in CHF patients (i.e., heavier patients do better).

Section snippets

Population

A total of 6,213 consecutive male veterans referred to one of two clinical exercise laboratories (Long Beach, California, 1987-1991; Palo Alto, California, 1992-2000) were used for analysis. From the total population, 522 patients had a history of CHF or clinical findings and test results. Echocardiograms were routinely obtained as part of the clinical evaluation but their measurements were not entered into our database. However, they did allow for exclusion of patients with serious valvular

Results

Although nonsustained ventricular tachycardia or frequent PVCs occurred in 18% of patients and 4% exhibited exertional hypotension during treadmill testing, there were no major complications in this group of CHF patients. A mean Borg scale of 17 was consistent with a near maximal effort in the majority of patients. The baseline data for the two groups along with subgroup comparisons between those who died and those who survived are included in Tables 1 and 2.

Discussion

In this population of patients with a history of CHF referred for exercise testing, mortality was higher in patients with lower exercise capacity (METs), lower BMI, ischemic etiology of CHF, and older age. A simple scoring system using these four parameters strongly predicts mortality.

Large academic centers that evaluate patients with advanced heart failure predominantly use peak VO2 consumption for prognostic information. The preponderance of published literature also focuses on this method of

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    *

    Reprint requests: Victor Froelicher, MD, Cardiology Division (111C), VA Palo Alto Health Care System, 3801 Miranda Ave, Palo Alto, CA 94304.

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