Distinguishing left ventricular hypertrophy from hypertrophic cardiomyopathy in adolescents: a longitudinal observation study

AIMS

Echocardiographic characteristics to distinguish physiological left ventricular (LV) hypertrophy from pathology are warranted in early adolescent athletes. This study aimed to explore the phenotype, progression, and potential grey zone of LV hypertrophy during adolescence in athletes and hypertrophic cardiomyopathy (HCM) genotype-positive patients.

METHODS AND RESULTS

In this longitudinal observation study, we compared seventy-six 12-year-old athletes with 55 age-matched and sex-matched HCM genotype-positive patients. Echocardiographic parameters were evaluated by using paediatric reference values (Z-scores). Hypertrophic cardiomyopathy genotype-positive patients were included if they had no or mild LV hypertrophy [maximum wall thickness <13 mm, Z-score <6 for interventricular septum diameter (ZIVSd), or posterior wall thickness]. We collected clinical data, including data on cardiac events. The mean follow-up-time was 3.2 ± 0.8 years. At baseline, LV hypertrophy was found in 28% of athletes and 21% of HCM genotype-positive patients (P = 0.42). Septum thickness values were similar (ZIVSd 1.4 ± 0.9 vs. 1.0 ± 1.3, P = 0.08) and increased only in HCM genotype-positive patients {ZIVSd progression rate -0.17 [standard error (SE) 0.05], P = 0.002 vs. 0.30 [SE 0.10], P = 0.001}. Left ventricular volume Z-scores (ZLVEDV) were greater in athletes [ZLVEDV 1.0 ± 0.6 vs. -0.1 ± 0.8, P < 0.001; ZLVEDV progression rate -0.05 (SE 0.04), P = 0.21 vs. -0.06 (SE 0.04), P = 0.12]. Cardiac arrest occurred in two HCM genotype-positive patients (ages 13 and 14), with ZIVSd 8.2-11.5.

CONCLUSION

Left ventricular hypertrophy was found in a similar proportion in early adolescence but progressed only in HCM genotype-positive patients. A potential grey zone of LV hypertrophy ranged from a septum thickness Z-score of 2.0 to 3.3. Left ventricular volumes remained larger in athletes. Evaluating the progression of wall thickness and volume may help clinicians distinguish physiological LV hypertrophy from early HCM.

Young athlete's growing heart: sex differences in cardiac adaptation to exercise training during adolescence

BACKGROUND

Athlete's heart is a condition of exercise-induced cardiac remodelling. Adult male endurance athletes more often remodel beyond reference values. The impact of sex on remodelling through adolescence remains unclear. Paediatric reference values do not account for patient sex or exercise history. We aimed to study the effect of sex on cardiac remodelling throughout adolescence.

METHODS

We recruited 76 male (M) and female (F) 12-year-old cross-country skiers in a longitudinal cohort study. Echocardiography was performed and analysed according to guidelines at age 12 (48 M, 28 F), 15 (34 M, 14 F) and 18 (23 M, 11 F). Repeated echocardiographic measurements were analysed by linear mixed model regression.

RESULTS

Males displayed greater indexed left ventricular end-diastolic volumes (LV EDVi) from age 12 (M 81±7 vs F 76±7, mL/m², p≤0.01), and progressed further until follow-up at age 18 (M 2.3±9.7 vs F -3.9±4.5 ΔmL/m², p≤0.01). LV EDVi remained above adult upper reference values in both groups. Males increased LV Mass Index from age 12 to 18 (M 33±27 vs F 4±19, Δg/m², p≤0.01). Males displayed LV mass above paediatric reference values at ages 15 and 18. A subset of males (35%) and females (25%) displayed wall thickness above paediatric reference values at age 12. Cardiac function was normal. There was no sex difference in exercise hours.

CONCLUSION

Sex-related differences in athlete's heart were evident from age 12, and progressed throughout adolescence. Remodelling beyond reference values was more frequent than previously reported, particularly affecting males. Age, sex and exercise history may assist clinicians in distinguishing exercise-induced remodelling from pathology in adolescents.

Cardiac remodelling in adolescent athletes – sex differences progress through adolescence

Background

Cardiac remodelling beyond reference values is well-known in adult athlete's heart. Male endurance athletes are more prone to develop cardiac chambers and wall thickness above reference values. Cardiac remodelling is also described in adolescent athletes, but considered to be moderate compared to adults. However, few studies evaluate adolescent athlete's heart by paediatric echocardiographic reference values. Current paediatric reference values are sex-unspecific and do not include exercise data. The impact of sex and exercise on remodelling in adolescent athlete's heart remains unclear.

Purpose

We aimed to study the development of cardiac remodelling and potential sex differences in adolescent athletes. We hypothesized that male adolescent athletes would display greater degree of remodelling compared to female adolescent athletes.

Methods

Male (M) and female (F) adolescent cross-country skiers were recruited in a longitudinal cohort study. They were examined with echocardiography at age 12, 15 and 18. Data on exercise was collected at all examinations. We evaluated echocardiographic parameters by paediatric reference values (Z-score: number of standard deviations above estimated mean in the given body surface area). Echocardiographic measures were considered above upper reference value if Z-score was ≥2.

Results

Seventy-six athletes were examined at age 12 (48 M, 28 F), 48 at age 15 (34 M, 14 F) and 34 at age 18 (23 M, 11 F). Although Z-scores were within reference values at age 12 (Table 1), a subset of athletes displayed Z-scores ≥2 for end-diastolic intraventricular septum diameter (IVSd, M 13/48=27%, F 5/28=18%) and left ventricular posterior wall thickness (LVPWd, M 6/48=13%, F 2/28=14%). The male group demonstrated enlarged left ventricular mass (LVM) from age 15 (Figure 1). Males had greater left ventricular end-diastolic volume (LV EDV) from age 12. Additional sex differences were evident from age 15 for IVSd, LVPWd and LVM (Table 1). There was no sex difference in exercise hours. Both groups had normal myocardial function through the study period.

Conclusion

Cardiac remodelling beyond reference values was observed in athletes of both sexes from early adolescent age. Sex differences were evident from age 12 with further progression. Pathological values for LVM were more frequent in males. These findings suggest that sex differences in exercise-induced cardiac remodelling is more prominent in adolescents than previously reported. Sex and exercise history should be considered in questions of pathology.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): The South-Eastern Norway Regional Health AuthorityCentre for Children and Youth Sport, Norwegian School of Sport Sciences