Left atrial volume index and outcome after transcatheter edge-to-edge valve repair for secondary mitral regurgitation.

AIMS: To investigate the role of left atrial volume index (LAVi) in patients with secondary mitral regurgitation (SMR) undergoing transcatheter edge-to-edge mitral valve repair (TEER). METHODS AND RESULTS: Outcomes were evaluated in SMR patients of a European multicentre registry according to baseline LAVi. Main analysis was performed for all-cause mortality; residual mitral regurgitation (MR) and New York Heart Association (NYHA) class improvement were analysed for patients available. A total of 1074 patients were included with a median LAVi (interquartile range) of 58 ml/m2 (46-73). Postprocedural reduction of MR grade to ≤2+ was similar across LAVi quintiles, ranging 91%-96% (p = 0.26). Symptomatic benefit (≥1 NYHA class improvement) also did not differ by LAVi quintiles (61%-68% of patients) (p = 0.66). The risk of mortality increased by 23%-42% in the four upper quintiles compared to the bottom quintile (LAVi <42 ml/m2 ). The hazard ratio (HR) of mortality was 1.35 (95% confidence interval [CI] 1.02-1.78, p = 0.035) associated with a LAVi >42 ml/m2 , which was attenuated after multivariable adjustment (HR 1.18, 95% CI 0.83-1.67, p = 0.36). A significant interaction was found for MR severity and pulmonary hypertension, with an increased risk of death associated with enlarged LAVi in patients with inframedian effective regurgitant orifice area (HR 1.99, 95% CI 1.06-3.74, p = 0.032) and in patients with systolic pulmonary pressure ≤50 mmHg (HR 1.67, 95% CI 1.02-2.75, p = 0.042) in multivariable analysis. CONCLUSION: Procedural success and symptomatic benefit were high throughout the whole range of LAVi. The prognostic impact of left atrial enlargement was relevant in patients with less severe SMR and without pulmonary hypertension, reinforcing the need to identify patients in the early course of backward congestion to achieve good long-term outcome after TEER.

Left Atrial Strain Determinants During the Cardiac Phases.

OBJECTIVES: The present study investigated the determinants of left atrial (LA) strain in all phases of the cardiac cycle. BACKGROUND: LA strain by speckle-tracking echocardiography allows the assessment of LA function in each phase of the cardiac cycle. However, its determinants and its relation with left ventricular (LV) function have not yet been fully described. METHODS: The authors performed a retrospective analysis in 127 patients with different cardiovascular pathologies. Using 2-dimensional speckle tracking in 4- and 2-chamber apical views we derived both LA and LV strain curves. Strain-strain loops were reconstructed using LV strain and the corresponding, synchronized LA strain data. Linear regressions were calculated for the entire strain-strain loop as well as for the 3 phases of the cardiac cycle (systole, and early and late diastole). The association between LA strain parameters and LV systolic and diastolic parameters was studied. The prediction of cardiovascular events was evaluated for both measured and predicted LA strain and other parameters. RESULTS: LA and LV strain curves presented excellent correlations with an R2 > 0.90 for the cardiac cycle, and R2 > 0.97 for its phases. Moreover, the ratios of LV/LA maximal volumes and the slopes of the LA-LV strain-strain loops of the individual patients correlated well (R2 = 0.75). In each phase of the cardiac cycle, LA strain parameters correlated well with the corresponding LV strain and the LV-LA volume ratio (R2 > 0.78). No significant difference in predictive ability of cardiovascular events or atrial fibrillation between the measured and predicted LA strain was observed (P > 0.05 for both). CONCLUSIONS: In the absence of abnormal LA/LV volume exchange, LA strain is, to a large extent, determined by LV strain and further modulated by the ratio of LV and LA volumes. Nonetheless, measuring LA strain is of high clinical interest because it integrates several parameters into a single, robust, and reproducible measurement.

Natural Shear Wave Imaging in the Human Heart: Normal Values, Feasibility, and Reproducibility.

Left ventricular myocardial stiffness could offer superior quantification of cardiac systolic and diastolic function when compared to the current diagnostic tools. Shear wave elastography in combination with acoustic radiation force has been widely proposed to noninvasively assess tissue stiffness. Interestingly, shear waves can also result from intrinsic cardiac mechanical events (e.g., closure of valves) without the need for external excitation. However, it remains unknown whether these natural shear waves always occur, how reproducible they can be detected and what the normal range of shear wave propagation speed is. The present study, therefore, aimed at establishing the feasibility of detecting shear waves created after mitral valve closure (MVC) and aortic valve closure (AVC), the variability of the measurements, and at reporting the normal values of propagation velocity. Hereto, a group of 30 healthy volunteers was scanned with high-frame rate imaging (>1000 Hz) using an experimental ultrasound system transmitting a diverging wave sequence. Tissue Doppler velocity and acceleration were used to create septal color M-modes, on which the shear waves were tracked and their velocities measured. Overall, the methodology was capable of detecting the transient vibrations that spread throughout the intraventricular septum in response to the closure of the cardiac valves in 92% of the recordings. Reference velocities of 3.2±0.6 m/s at MVC and 3.5±0.6 m/s at AVC were obtained. Moreover, in order to show the diagnostic potential of this approach, two patients (one with cardiac amyloidosis and one undergoing a dobutamine stress echocardiography) were scanned with the same protocol and showed markedly higher propagation speeds: the former presented velocities of 6.6 and 5.6 m/s; the latter revealed normal propagation velocities at baseline, and largely increased during the dobutamine infusion (>15 m/s). Both cases showed values consistent with the expected changes in stiffness and cardiac loading conditions.