Background
The aim of this study was to define the range of left ventricular (LV) velocities and deformation indexes in highly trained athletes, analyzing potential differences induced by different long-term training protocols.
Methods
Standard echocardiography, pulsed-wave tissue Doppler echocardiography, and two-dimensional strain echocardiography of the interventricular septum and lateral wall were performed in 370 endurance athletes and 280 power athletes. Using pulsed-wave tissue Doppler, the following parameters of myocardial function were assessed: systolic peak velocities (S m ), early (E m ) and late (A m ) diastolic velocities, and the E m /A m ratio. By two-dimensional strain echocardiography, peaks of regional systolic strain and LV global longitudinal strain were calculated.
Results
LV mass index and ejection fraction did not significantly differ between the two groups. However, power athletes showed an increased sum of wall thicknesses ( P < .01) and relative wall thickness, while LV stroke volume and LV end-diastolic diameter ( P < .001) were greater in endurance athletes. By pulsed-wave tissue Doppler analysis, E m and E m /A m at both the septal and lateral wall levels were higher in endurance athletes. By two-dimensional strain echocardiography, myocardial deformation indexes were comparable between the two groups. E m /A m ratios ≥ 1 were found in the overall population, while 90 % of athletes had an E m ≥ 16 cm/sec, S m ≥ 10 cm/sec, and global longitudinal strain ≤ −16%. Multivariate analyses evidenced independent positive association between Em peak velocity and LV end-diastolic volume ( P < .001) and an independent correlation of global longitudinal strain with the sum of LV wall thicknesses ( P < .005).
Conclusions
This study describes the full spectrum of systolic and diastolic myocardial velocities and deformation indexes in a large population of competitive athletes.
Athlete’s heart is a cardiac adaptation to long-term, intensive training including increased cavity diameters, wall thickness, and left ventricular (LV) mass. Conventional Doppler echocardiography is widely used to evaluate athlete’s heart and to distinguish it from LV diseases. Furthermore, pulsed-wave tissue Doppler and two-dimensional strain echocardiographic (2DSE) analysis have recently been applied in the evaluation of either physiologic or pathologic LV hypertrophy.
The aim of the present study was to define the full range of LV velocities and deformation indexes in a large population of highly trained athletes, analyzing possible differences induced by different long-term training protocols.
Methods
Study Population
From June 2007 to April 2009, 650 consecutive highly trained athletes were referred to the Sports Medicine Ambulatory Service of Monaldi Hospital (Naples, Italy) for cardiovascular preparticipation screening and afterward to our echocardiographic laboratory for the purpose of the present study. All subjects underwent detailed histories, physical examinations, electrocardiography, chest radiography, and comprehensive transthoracic echocardiography, including standard Doppler, pulsed-wave tissue Doppler, and 2DSE studies. On the basis of their training protocols, the athletes were categorized into two groups: 370 endurance-trained athletes (ATE) and 280 power athletes (ATP). The study was approved by the local ethics committee.
Exclusion criteria were coronary artery disease, arterial hypertension, valvular and congenital heart disease, bicuspid aortic valve, congestive heart failure, cardiomyopathies, diabetes mellitus, sinus tachycardia, use of anabolic steroids and of other drugs, and echocardiograms of inadequate quality.
Training Protocols
Because the specific nature of sports training has a major influence on cardiac structural adaptations, our athletes were selected on the basis of their training protocols. All the subjects had been trained intensively for 15 to 20 hours/week for >4 years.
The ATE group (long-distance and middle-distance swimming or running, soccer, and basketball) was submitted to intensive aerobic isotonic dynamic exercise at incremental workloads of 70% to 90% of maximal heart rate. In particular, they performed 3 hours/day of incremental long-distance swimming (7,000 m/day divided into series of 400–800 m) or 3 hours/day of long-distance running and only 2 hours/week of weightlifting at low workload.
On the other hand, the ATP group (weightlifting, martial arts, and windsurfing) underwent anaerobic isometric static exercise at incremental workloads of at 40% to 60% of maximal heart rate. In particular, their training protocol included both 2 hours/day of short-distance running and 3 hours/day of weightlifting at high workload.
Imaging Protocol
Standardized transthoracic echocardiographic, Doppler, pulsed-wave tissue Doppler, and 2DSE examinations were performed using commercially available equipment in all subjects (Vivid 7; GE Healthcare, Milwaukee, WI). Specific views included the parasternal long-axis and short-axis views (at the mitral valve and papillary muscle levels); apical four-chamber, two-chamber, and three-chamber views; and subcostal views, including respiratory motion of the inferior vena cava. Pulsed-wave and continuous-wave Doppler interrogation was performed on all four cardiac valves.
All studies were reviewed and analyzed offline by two independent observers blinded to the clinical characteristics of the study population. Specific measurements were made by the average of three to five cardiac cycles.
M-Mode and B-Mode Measurements
M-mode measurements (LV diastolic and systolic diameters, interventricular septal and posterior wall thickness, and left atrium) were performed in the parasternal long-axis view with the patient in the left lateral position. LV mass was calculated by the Penn convention and indexed for height 2.7 (Cornell adjustment). Relative diastolic wall thickness was determined as the ratio between the sum of septal and posterior wall thicknesses and LV end-diastolic diameter. Circumferential end-systolic stress (ESSc) was calculated as a measurement of LV afterload using a cylindrical model according to the following formula:
ESSc ( g / c m 2 ) = SBP × 0.5 D s 2 { 1 + [ ( 0.5 Ds + Ps ) 2 / ( 0.5 Ds + 0.5 Ps ) 2 ] } / ( 0.5 Ds + Ps ) 2 − 0.5 D s 2 ,
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