Plasma Brain Natriuretic Peptide Levels in a Population of Young Athletes: Correlation with Echocardiographic Parameters

Publication Date

4-2006

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Exercise and Sport Studies, Biophysical Studies

Department

Kinesiology

Supervisory Committee Chair

Ronald P. Pfeiffer

Supervisory Committee Member

Michael S. Womack

Supervisory Committee Member

Mark DeBeliso

Supervisory Committee Member

Chad Harris

Abstract

BACKGROUND: Annual cardiovascular screening of young athletes prior to taking part in organized sports is recommended by major medical organizations in the United States. However, the American Heart Association’s position statement regarding preparticipation physicals concedes that it is an unrealistic expectation to pick up most cardiac problems, let alone common causes of sudden cardiac death, during these exams. Part of the difficulty is that the most common cause of sudden death in young athletes, hypertrophic cardiomyopathy (HCM), is often clinically silent and shares some characteristics with normal physiologic adaptations to exercise, including increase in left ventricular mass, collectively termed the athlete’s heart syndrome. To date, there have been no screening tests for HCM found to be sufficiently sensitive, cost-effective, and minimally invasive to be incorporated into general practice in the U.S.

Brain, or B-type, natriuretic peptide (BNP) is a hormone normally released by the heart in response to left ventricular wall stress. BNP levels have been evaluated in normal adults and children as well as in adult athletes. Several studies have documented elevation of BNP levels in patients with HCM compared to controls. However, there are currently no data regarding normal levels of BNP in young athletes, and contradictory data regarding levels of BNP in adult athletes. It is therefore unknown whether an athletic population regularly screened and potentially at risk for sudden cardiac death from HCM exhibits levels of BNP within the normal physiologic range expected for its age group, or whether BNP levels rise in proportion to left ventricular mass in healthy subjects.

PURPOSE: To determine normal levels of plasma BNP in adolescent athletes and evaluate their correlation to cardiac parameters determined by echocardiography.

METHODS: Physical exam, electrocardiography, plasma BNP measurement by rapid fluorescent immunoassay and limited echocardiography were performed on 30 healthy male adolescent high school football players (16.0 +/- 1.1 years). Left ventricular (LV) mass was then calculated using the Penn-cube formula of Devereux and Reichek and divided by body surface area determined by the DuBois formula to give LV mass index. Relative wall thickness (RWT) was calculated as interventricular septal thickness (IVSTd) + posterior wall thickness (PWTd) / left ventricular end diastolic dimension (LVEDD). Pearson correlation coefficients with linear regression analysis for significance, set at p ≤ 0.05, were used to assess relationships between plasma BNP levels and cardiac parameters. RESULTS: Plasma BNP for this population was 11.9 +/- 10.2 pg/ml. There was no correlation between BNP and IVSTd (r = -0.15, p = 0.44), RWT (r = -0.04, p = 0.84), LV mass (r = 0.05, p = 0.79), or LV mass index (r = 0.11, p = 0.55). CONCLUSION: Plasma BNP levels in adolescent athletes are within the ranges of previously described normal adolescents and have no correlation to LV mass, even when corrected for body surface area.

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