Clinical Investigation
Left Ventricular Function in Various Disorders
Mechanical Dispersion by Strain Echocardiography: A Novel Tool to Diagnose Hypertrophic Cardiomyopathy in Athletes

https://doi.org/10.1016/j.echo.2016.11.013Get rights and content

Background

Previous studies have demonstrated that global longitudinal strain (GLS) is altered in patients with hypertrophic cardiomyopathy (HCM) in comparison with athletes. Nevertheless, these results rely on studies comparing sedentary patients with HCM with healthy athletes. The aims of this study were to confirm these findings in an appropriate group of athletes with HCM and to study the additive value of novel parameters (i.e., mechanical dispersion and exercise GLS).

Methods

Thirty-six athletes with HCM were prospectively included and were compared with 36 sedentary patients with HCM, 36 healthy athletes, and 36 sedentary control subjects of similar age. Athlete groups had similar training duration and HCM groups similar maximal wall thickness. All underwent echocardiography at rest and during submaximal exercise. GLS was assessed; the SD of time to maximal myocardial shortening of longitudinal strain was calculated as a parameter of mechanical dispersion.

Results

The HCM sedentary group showed the lowest resting and exercise GLS. Resting GLS was not different between athletes with HCM and the two control groups, but exercise GLS enabled the differentiation of athletes with HCM from healthy athletes. Mechanical dispersion was higher in both HCM groups compared with both control groups at rest and during exercise. Receiver operating characteristic analysis in the athlete groups demonstrated that resting mechanical dispersion (area under the curve = 0.949 ± 0.023) had better ability to identify HCM compared with GLS at rest (area under the curve = 0.644 ± 0.069) (P < .001) or during exercise (area under the curve = 0.706 ± 0.066) (P < .005).

Conclusions

In athletes, normal resting GLS does not rule out the diagnosis of HCM. Mechanical dispersion of longitudinal strain seems to be a promising tool for the diagnosis of HCM in athletes.

Introduction

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Regular intense physical activity can induce electrical and myocardial adaptations referred to as “athlete's heart.”1 Morphologic adaptations are characterized by an enlargement of the cardiac chambers associated with a moderate increase in left ventricular (LV) wall thickness. In most cases the diagnosis of athlete's heart is easy. However, despite clinical and cardiac imaging characteristics proposed to differentiate athlete's heart and hypertrophic cardiomyopathy (HCM),1, 2 in a few cases doubt may persist. Yet this diagnosis is important, because HCM is one of the most common causes of sudden cardiac death in young athletes.1

The use of strain analysis is now recommended in HCM as a clinical tool for the evaluation of LV systolic function.3 Thus, a decrease in global longitudinal strain (GLS) has been proposed to distinguish HCM from athlete's heart.4, 5 Furthermore, it has been shown that because of myocardial disarray and fibrosis, systolic contraction in HCM is heterogeneous, in contrast to the homogenous contraction in athletes.6 Mechanical dispersion assessed by two-dimensional strain reflects heterogeneous myocardial contraction.7

The main weakness of these studies was that they compared sedentary patients with HCM with healthy athletes.4, 5, 6 Indeed, it has been reported that some athletes with proven HCM are able to exercise at very high levels, probably because of good LV compliance.8, 9 In the same way, a recent study demonstrated that athletes with HCM have better systolic and diastolic function than sedentary patients with HCM.10 But to our knowledge, resting GLS has not been compared between athletes with HCM and sedentary patients with HCM.

Moreover, it must be underlined that previous results concerned only the resting state, although the evaluation of athlete's heart response to exercise seems promising.11 GLS analysis during exercise is still scarce, even if its feasibility and its interest have already been reported in previous studies in healthy athletes and in patients with HCM.12, 13, 14

Thus, the aims of this study were (1) to compare resting GLS in sedentary patients with HCM and in athletes with HCM and (2) to study the additive value of mechanical dispersion and of exercise GLS in the diagnosis of HCM. For these purposes, four populations, athletes with HCM, sedentary patients with HCM, healthy athletes, and sedentary control subjects were included.

Section snippets

Athletes with HCM

From December 2008 to May 2013, 36 athletes with confirmed diagnoses of HCM were prospectively enrolled in the Department of Sport Medicine of our institution (Figure 1). Athletes had trained >4 hr/wk during the past 5 years and regularly took part in competition at inclusion. The diagnosis of HCM was performed because of symptoms or workup of cardiovascular abnormalities (mainly electrocardiographic abnormalities) during competitive sports' preparticipation evaluation. The diagnosis of HCM was

Demographic Parameters and Cardiopulmonary Exercise Test Characteristics of the Four Groups

As specified by the inclusion criteria, the physical training duration was similar in both trained groups (6.3 ± 2.9 hr/wk in athletes with HCM and 7.3 ± 4.3 hr/wk in healthy athletes, P = .880) (Table 1). Sports disciplines included were cycling (n = 48 [66.7%]), running (n = 6 [8.3%]), soccer (n = 12 [16.6%]), tennis (n = 2 [2.8%]), basketball (n = 2 [2.8%]), and rugby (n = 2 [2.8%]). The exercise capacity of athletes with HCM (108.1 ± 21.1% of predicted maximal oxygen uptake peak value) was

Discussion

In this study, we clearly demonstrated that athletes with HCM and sedentary patients with HCM present different phenotypes. Indeed, athletes with HCM have better systolic and diastolic function than sedentary patients with HCM, associated with better functional status than sedentary patients with HCM. These phenotypic differences make the diagnosis of HCM in athletes even more challenging. Our results show that normal GLS at rest cannot be used to exclude the diagnosis of HCM in an athlete;

Conclusions

Normal GLS at rest is not sensitive enough to discard the diagnosis in athletes suspicious for HCM. The use of exercise echocardiography increases the diagnosis value of GLS. However, it seems easier and more robust to assess mechanical dispersion of longitudinal strain, which seems to be a promising tool for the diagnosis of HCM in athletes.

Acknowledgments

We thank all the patients for participating in the study. We also thank Patricia Bouillet for her assistance in the inclusion of the patients.

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Drs. Carré and Donal contributed equally as senior authors.

This study was supported by a grant from Ligue Contre la Cardiomyopathie.

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