Thanh-Thao Ton-Nu

Myocardial Injury and Ventricular Dysfunction Related to Training Levels Among Nonelite Participants in the Boston Marathon

Background— Multiple studies have individually documented cardiac dysfunction and biochemical evidence of cardiac injury after endurance sports; however, convincing associations between the two are lacking. We aimed to determine the associations between the observed transient cardiac dysfunction and biochemical evidence of cardiac injury in amateur participants in endurance sports and to elicit the risk factors for the observed injury and dysfunction. Methods and Results— We screened 60 nonelite participants, before and after the 2004 and 2005 Boston Marathons, with echocardiography and serum biomarkers. Echocardiography included conventional measures as well as tissue Doppler–derived strain and strain rate imaging. Biomarkers included cardiac troponin T (cTnT) and N-terminal pro-brain natriuretic peptide (NT-proBNP). All subjects completed the race. Echocardiographic abnormalities after the race included altered diastolic filling, increased pulmonary pressures and right ventricular dimensions, and decreased right ventricular systolic function. At baseline, all had unmeasurable troponin. After the race, >60% of participants had increased cTnT >99th percentile of normal (>0.01 ng/mL), whereas 40% had a cTnT level at or above the decision limit for acute myocardial necrosis (≥0.03 ng/mL). After the race, NT-proBNP concentrations increased from 63 (interquartile range [IQR] 21 to 81) pg/mL to 131 (IQR 82 to 193) pg/mL (P<0.001). The increase in biomarkers correlated with post-race diastolic dysfunction, increased pulmonary pressures, and right ventricular dysfunction (right ventricular mid strain, r=−0.70, P<0.001) and inversely with training mileage (r=−0.71, P<0.001). Compared with athletes training >45 miles/wk, athletes who trained ≤35 miles/wk demonstrated increased pulmonary pressures, right ventricular dysfunction (mid strain 16±5% versus 25±4%, P<0.001), myocyte injury (cTnT 0.09 versus <0.01 ng/mL, P<0.001), and stress (NT-proBNP 182 versus 106 pg/mL, P<0.001). Conclusions— Completion of a marathon is associated with correlative biochemical and echocardiographic evidence of cardiac dysfunction and injury, and this risk is increased in those participants with less training.

Direct Measurement of Vena Contracta Area by Real-Time 3-Dimensional Echocardiography for Assessing Severity of Mitral Regurgitation

We tested the hypothesis that the vena contracta (VC) cross-sectional area in patients with mitral regurgitation (MR) can be reproducibly measured by real-time 3-dimensional (3D) echocardiography and correlates well with the volumetric effective regurgitant orifice area (EROA). Earlier MR repair requires accurate noninvasive measures, but practically, the VC area is difficult to image in 2-dimensional views, which are often oblique to it. 3D echocardiography can provide an otherwise unobtainable true cross-sectional view. In 45 patients with mild or greater MR, 44% eccentric, 2-dimensional and 3D VC areas were measured and correlated with the EROA derived from the regurgitant stroke volume. Real-time 3D echocardiography of the VC area correlated and agreed well with the EROA for both central and eccentric jets (r(2) = 0.86, SEE 0.02 cm(2), difference 0.04 +/- 0.06 cm(2), p = NS). For eccentric jets, 2-dimensional echocardiography overestimated the VC width compared with 3D echocardiography (p = 0.024) and correlated more poorly with the EROA (r(2) = 0.61 vs 0.85, p <0.001), causing clinical misclassification in 45% of patients with eccentric MR. The interobserver variability for the 3D VC area was 0.03 cm(2) (7.5% of the mean, r = 0.95); the intraobserver variability was 0.01 cm(2) (2.5% of the mean, r = 0.97). In conclusion, real-time 3D echocardiography accurately and reproducibly quantified the vena contracta cross-sectional area in patients with both central and eccentric MR. Rapid acquisition and intuitive analysis promote practical clinical application of this central, directly visualized, measure and its correlation with outcome.

Assessment of right ventricular function by real-time three-dimensional echocardiography improves accuracy and decreases interobserver variability compared with conventional two-dimensional views.

AIMS Two-dimensional echocardiographic (2DE) assessment of right ventricular (RV) function is difficult, often resulting in inconsistent RV evaluation. Real-time three-dimensional echocardiography (RT3DE) allows the RV to be viewed in multiple planes, which can potentially improve RV assessment and limit interobserver variability when compared with 2DE. METHODS AND RESULTS Twenty-five patients underwent 2DE and RT3DE. Views of 2DE (RV inflow, RV short axis, and apical four-chamber) were compared with RT3DE views by four readers. RT3DE data sets were sliced from anterior-posterior (apical view) and from base to apex (short axis) to obtain six standardized planes. Readers recorded the RV ejection fraction (RVEF) from 2DE and RT3DE images. RVEF recorded by RT3DE (RVEF(3D)) and 2D (RVEF(2D)) were compared with RVEF by disc summation (RVEF(DS)), which was used as a reference. Interobserver variability among readers of RVEF(3D) and RVEF(2D) was then compared. Overall, mean RVEF(DS), RVEF(3D), and RVEF(2D) were 37 +/- 11%, 38 +/- 10%, 41 +/- 10%, respectively. The mean difference of RVEF(3D)-RVEF(DS) was significantly less than RVEF(2D)-RVEF(DS) (3.7 +/- 4% vs. 7.1 +/- 5%, P = 0.0066, F-test). RVEF(3D) correlated better with RVEF(DS) (r = 0.875 vs. r = 0.69, P = 0.028, t-test). RVEF(3D) was associated with a 39% decrease in interobserver variability when compared with RVEF(2D) [standard deviation of mean difference: 3.7 vs. 5.1, (RT3DE vs. 2DE), P = 0.018, t-test]. CONCLUSIONS RT3DE provides improved accuracy of RV function assessment and decreases interobserver variability when compared with 2D views.

Progressive nature of chronic mitral regurgitation and the role of tissue Doppler-derived indexes

The aim of this study was to determine whether severe mitral regurgitation (MR) is progressive and whether tissue-Doppler (TD)-derived indexes can detect early left ventricular (LV) dysfunction in chronic severe MR. Percutaneous rupture of mitral valve chordae was performed in pigs (n = 8). Before MR (baseline), immediately after MR (post-MR), and at 1 and 3 mo after MR, cardiac function was assessed using conventional and TD-derived indexes. The severity of MR was quantified using regurgitant fraction and effective regurgitant orifice area (EROA). In all animals, MR was severe. On follow-up, the LV dilated progressively over time, but LV ejection fraction did not decrease. With the increase in LV dimensions, the forward stroke volume remained unchanged, but the mitral annular dimensions, EROA, and regurgitant fraction increased (EROA = 41 +/- 2 and 51 +/- 2 mm(2) post-MR and at 3 mo, respectively, P < 0.01). Peak systolic myocardial velocities, strain, and strain rate increased acutely post-MR and remained elevated at 1 mo but declined by 3 mo (anterior strain rate = 2.9 +/- 0.1 and 2.4 +/- 0.2 s(-1) post-MR and at 3 mo, respectively, P < 0.001). Therefore, in a chronic model of MR, serial echocardiography demonstrated that MR begets MR and that those TD-derived indexes that initially increased post-MR decreased to baseline before any changes in LV ejection fraction.