Exercise-induced cardiac remodeling in non-elite endurance athletes: Comparison of 2-tiered and 4-tiered classification of left ventricular hypertrophy

Abstract

Background: Long-term endurance sport practice leads to eccentric left ventricular hypertrophy (LVH). We aimed to compare the new 4-tiered classification (4TC) for LVH with the established 2-tiered classification (2TC) in a cohort of normotensive non-elite endurance athletes.

Methods: Male participants of a 10-mile race were recruited and included when blood pressure (BP) was normal (<140/90 mmHg). Phenotypic characterization of LVH was based on relative wall thickness (2TC), and on LV concentricity2/3 (LV mass/end-diastolic volume [LVM/EDV]2/3) plus LVEDV index (4TC). Parameters of LV geometry, BP, cumulative training hours, and race time were compared between 2TC and 4TC by analysis of variance, and post-hoc analysis.

Results: Of 198 athletes recruited, 174 were included. Mean age was 41.6±7.5 years. Forty-two (24%) athletes had LVH. Allocation in the 2TC was: 32 (76%) eccentric LVH and 10 (24%) concentric LVH. Using the 4TC 12 were reclassified to concentric LVH, and 2 to eccentric LVH, resulting in 22 (52%) eccentric LVH (7 non-dilated, 15 dilated), and 20 (48%) concentric LVH (all non-dilated). Based on the 2TC, markers of endurance training did not differ between eccentric and concentric LVH. Based on the 4TC, athletes with eccentric LVH had more cumulative training hours and faster race times, with highest values thereof in athletes with eccentric dilated LVH.

Conclusions: In our cohort of normotensive endurance athletes, the new 4TC demonstrated a superior discrimination of exercise-induced LVH patterns, compared to the established 2TC, most likely because it takes three-dimensional information of the ventricular geometry into account.

Fig 1. Schematic illustration of the four-tiered classification of left ventricular hypertrophy.

LV EDV indicates left ventricular end-diastolic volume; BSA, body surface area; and LVH, left ventricular hypertrophy.

Fig 2. Impact of cumulative lifetime endurance training and 10 mile race time on LV mass illustrated for normal (<120/80 mmHg, filled circles) and non-optimal (120/80-139/89 mmHg, empty circles) blood pressure.

Solid line indicates linear regression for athletes with normal blood pressure and dashed line linear regression for athletes with non-optimal blood pressure.

Fig 3. Number of athletes in each tier of the 2TC and 4TC, as well as number of athletes who were reclassified from 2TC to 4TC.

LV end-diastolic volume and LV length are indicated inside or next to the schematic representations of the ventricles (mean ± SD). Training characteristics are indicated by the number of runner symbols (cumulative lifetime training (hours)/10 mile race time (min): 1 runner: <4000 and/or ≥70; 2 runners: 4000 to 5999 and/or 65 to 69; 3 runners: 6000–7999 and/or 60 to 64; 4 runners: ≥8000 and/or <60).

Fig 4. Echocardiography images of M-mode and apical two-chamber views.

Athlete 1 was classified as eccentric LVH with 2TC due to a LVID of 57.1 mm and a PWT of 9.8 mm resulting in a relative wall thickness of 0.34. He was reclassified with 4TC to concentric non-dilated LVH due to a relative short LV length of 8.2 cm and an associated LV EDV/BSA of 60.1 ml/m² resulting in a Concentricity of 10.4 ml/m^2/3. Athlete 2 was also classified as eccentric LVH with 2TC due to a LVID of 53.6 mm and a PWT of 10.6 mm resulting in a relative wall thickness of 0.40. In contrast to Athlete 1, Athlete 2 was reclassified with 4TC to eccentric non-dilated LVH due to a longer LV length of 9.3 cm and an associated higher LV EDV/BSA of 71.5 ml/m² resulting in a smaller Concentricity of 8.7 ml/m^2/3.