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 (LA) volume index in patients with secondary mitral regurgitation (SMR) undergoing transcatheter edge-to-edge mitral valve repair (TEER).

METHODS

Outcomes were evaluated in SMR patients of a European multicenter registry according to baseline left atrial volume index (LAVi). Main analysis was performed for all-cause mortality; residual MR and NYHA class improvement were analyzed for patients available.

RESULTS

1,074 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% to 42% in the four upper quintiles compared to the bottom quintile (LAVi <42ml/m² ). The hazard ratio of mortality was 1.35 (95%-CI 1.02-1.78, p=0.035) associated with a LAVi >42ml/m² , which was attenuated after multivariable adjustment (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 regurgitation orifice area (EROA, 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 LA 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.

Systematic prolonged video-electroencephalograms identify electrographic seizures in 5% of acute stroke patients with aphasia

In stroke units, diagnosing seizures may be difficult, especially in aphasic patients. We discuss herein our systematic 4-hour video EEG monitoring of 61 patients with aphasia within the first 72hours after the onset of ischaemic stroke. Five electrographic seizures were identified in 3 patients, with no clinical signs apparent on the video and no symptoms reported by patients. We did not record status epilepticus nor generalized seizure. Comparative analyses disclosed a higher risk of early seizures in patients with haemorrhagic transformation. Video EEG monitoring detected electrographic seizures in 5% of stroke patients with aphasia. This monitoring could be useful for selected patients, especially those with haemorrhagic transformation.

556 Shear wave imaging using ultra-high frame rate echocardiography for the assessment of structural changes in cardiac transplant recipients

Background

Cardiac allografts undergo characteristic alterations of the extracellular matrix, including myocardial fibrosis, that contribute to functional changes, particularly diastolic dysfunction due to increased myocardial stiffness(MS). Histological examination is the gold standard for myocardial fibrosis quantification, however, it requires endomyocardial biopsies which are invasive and not without risk. Increased native T1 and extracellular volume(ECV) using CMR T1 mapping have shown good correlation with biopsy evidence of myocardial interstitial fibrosis in heart transplant(HTx) recipients. Echocardiographic shear wave(SW) elastography is an emerging approach for measuring MS in vivo. SWs occur after mechanical excitation of the myocardium, e.g. after mitral(MVC) and aortic valve closure(AVC), and their propagation velocity is directly related to MS, thus providing an opportunity to assess stiffness at end-diastole(ED) and end-systole(ES).

Purpose

The aim was to investigate if natural shear wave velocities increase with the degree of diffuse myocardial fibrosis in HTx recipients.

Methods

We prospectively enrolled 22 HTx patients (8.8 ± 5.9 years post-HTx) that underwent CMR during their annual check-up. We performed SW elastography in parasternal long axis views of the left ventricle(LV) using an experimental scanner (HD-PULSE) equipped with a clinical phased array transducer (Samsung Medison P2-5AC) at 1100 ± 250 frames per second. Tissue acceleration maps were extracted from an anatomical M-mode line along the midline of the LV septum. The SW propagation velocity at MVC and AVC was measured as the slope on the M-mode acceleration map(FigureA). All patients underwent right heart catheterization on the same day for the measurement of pulmonary capillary wedge pressure(PCWP), as surrogate for LV filling pressure. The CMR protocol consisted of standard sequences including native and post-contrast T1 mapping. To evaluate diffuse myocardial fibrosis, native T1 and ECV were measured in the anteroseptal wall over all available short-axis slices.

Results

We found good correlations between SW velocities at ED and both myocardial T1 (r = 0.8,p &lt; 0.001,FigureB) and ECV (r = 0.6,p &lt; 0.05,FigureC) measured with CMR. Similarly, we found significant correlations between SW velocities at ES and T1 (r = 0.7,p &lt; 0.005) and ECV (r = 0.5,p &lt; 0.05), respectively. Furthermore, we observed a significant correlation between SW velocities at ED and PCWP (r = 0.6,p &lt; 0.05).

Conclusions

Both end-diastolic and end-systolic shear wave velocities showed a good correlation with CMR defined myocardial fibrosis in cardiac transplant patients. Shear wave velocities at end-diastole correlated with invasively-determined left ventricular filling pressure, reflecting the impact of the fibrous changes on the left ventricular diastolic function. These results suggest the potential of cardiac shear wave elastography for the assessment of structural changes in cardiac transplant recipients.

Abstract 556 Figure.

P2476Non-invasive left ventricular stiffness measurements for assessing diastolic myocardial properties after orthotopic heart transplantation

Background

After orthotopic heart transplantation (HTx), allografts undergo characteristic alterations including myocardial fibrosis. These histologic changes contribute to functional impairment, especially to increased passive myocardial stiffness (MS), which is an important pathophysiological determinant of left ventricular diastolic dysfunction (DF). However, the transplanted heart is affected by many factors that make the interpretation of diastolic echocardiographic parameters difficult. Echocardiographic shear wave (SW) elastography is an emerging approach for measuring MS in vivo. Natural SWs occur after mechanical excitation of the myocardium, e.g. after mitral (MVC), and their propagation velocity is directly related to MS, thus providing an opportunity to assess stiffness at end-diastole (ED).

Purpose

The aim was to evaluate the relationship between MS and diffuse myocardial fibrosis as mechanism of DF in HTx patients.

Methods

We prospectively enrolled 33 patients (10.3±6.3 years after HTx) that underwent right heart catheterization (all) and CMR (n=18) during their annual check-up. We performed SW elastography in parasternal long axis views of the LV using a fully programmable experimental scanner (HD-PULSE) equipped with a clinical phased array transducer (Samsung Medison P2–5AC) at 1100±250 frames per second. Tissue acceleration maps were extracted from an anatomical M-mode line along the midline of the LV septum. The ED SW propagation velocity was measured as the slope in the M-mode image (Figure A). Right heart catheterization was performed on the same day. HTx patients were assumed to have diastolic dysfunction (DDF) if the pulmonary capillary wedge pressure (PCWP) exceeded 18mmHg (n=9). All other patients were assumed to have normal diastolic function (NDF, n=24). Native T1 and extracellular volume (ECV) were measured to evaluate diffuse myocardial fibrosis.

Results

Positive correlations were found between SW velocities at ED and PCWP (r=0.61, p<0.001; Figure B), between SW velocities at ED and T1 (r=0.80, p<0.001; Figure D), and between SW velocities at ED and ECV (r=0.66, p=0.004). SW propagation velocities at ED were significantly higher in DDF than in NDF (8.05±1.85 vs. 3.77±1.02 m/s; p<0.001; Figure C), and corresponded to the T1 values (as illustrated in Figure D).

Conclusions

End-diastolic shear wave velocity – as a measurement of passive myocardial stiffness – showed a good correlation with CMR defined myocardial fibrosis. High PCWPs were consistent with the increase in SW velocities, reflecting the fibrous changes in the ventricle. These findings thus suggest that cardiac shear wave elastography has the potential to become a powerful tool for the assessment of diastolic myocardial properties in cardiac transplant recipients.

P1501Can we measure the stiffening of hypertensive hearts non-invasively? A shear wave imaging study using ultra-high frame rate echocardiography

Background

Cardiac shear wave (SW) elastography is a novel technique based on high-frame-rate (HFR) echocardiography which has been shown to be related to myocardial stiffness. In this study we explore the relation between myocardial SW velocity and myocardial remodelling in remodelled hearts of patients with arterial hypertension (AH).

Methods

We prospectively included 33 treated AH patients with hypertrophic left ventricular (LV) remodelling (59±14 years, 55% male) and 26 aged matched healthy controls (55±15 years, 77% male). AH patients were further divided according to their LV geometric pattern into a concentric remodelling (CR) group (13 patients) and a concentric hypertrophy (CH) group (20 patients). LV parasternal long axis views were acquired with an experimental HFR ultrasound scanner (HD-PULSE) at 1266±317 frames per seconds. Myocardial acceleration maps were created from the HFR-datasets and an anatomical M-mode line was drawn along the midline of the interventricular septum (IVS). The propagation velocity of natural SWs occurring at mitral valve closure (MVC) was measured on these M-modes (Figure A) in order to assess passive myocardial stiffness. Standard echocardiography using a commercial scanner was performed to evaluate LV remodelling.

Results

SW velocities at MVC differed significantly between AH patients and controls (5.83±1.20 m/s vs. 4.04±0.96 m/s; p<0.001). Within the patient group, patients with CH had highest SW velocities at MVC (p<0.001), whereas values between controls and patients with CR were comparable (p=0.075) (Figure B). In AH patients, significant positive correlations were found between SW velocity at MVC and parameters of LV remodelling (IVS thickness: r=0.728, p<0.001; LV mass index: r=0.780, p<0.001, LV end-diastolic volume: r=0.604, p=0.008) (Figure C) and also parameters of diastolic function (E/e': r=0.495, p=0.005, left atrium diameter: r=0.866, p<0.001, left atrium volume index: r=0.661, p<0.001).

Figure A, B, C

Conclusions

SW velocity – and therefore myocardial stiffness – is higher in AH patients compared to healthy controls and increases with increasing severity of hypertensive heart disease. Patients with concentric remodelling have still close-to-normal passive myocardial properties while patients with concentric hypertrophy show significant stiffening. Echocardiographic shear wave elastography is a promising new technique for the non-invasive assessment of myocardial stiffness and might provide valuable new insights into myocardial function and the pathophysiology of myocardial disease.

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.

Serological identification of Shigella flexneri strains by the coagglutination reaction

Several variants of reagents were prepared by coupling type (I, II III, IV, V and VI) and group (3, 4, 6 and 7, 8, 9) anti-Shigella flexneri sera with protein A--containing staphylococcal suspension. For most serum lots coagglutination led to a 1/10 minimum dilution. However, different efficiencies were reported between serum lots and even within the same type or group. No improvement by the coagglutination reaction could be obtained for one lot from group 3, 4 and 7, 8, 9 sera and for both type IV serum lots. The coagglutination reactions were specific both with collection strains and with recently isolated strains and the two staphylococcal suspension lots showed an identical behaviour. Coagglutination may be used for obtaining a better efficiency of type and group. Shigella flexneri sera but this varies in terms of the serum lot and the serum/Staphylococcus combination used.

Serotyping of Pseudomonas aeruginosa strains by slide coagglutination

Serological typing of Pseudomonas aeruginosa strains (228 strains) by slide coagglutination, using our own reagents (5 polyvalent and 22 monovalent ones, corresponding to the 22 serotypes in Meitert-Meitert scheme), led to identical results obtained by conventional slide agglutination. Utilization of live Ps. aeruginosa cells suspensions, killed by boiling or autoclaving, showed a 100% concordance of results, when using the second and the third suspension types and a 97.37% one between them and the live cells suspension. We noticed that reactions intensity was higher when using bacterial suspensions, boiled for 2.5 hours, in comparison with autoclaved cells suspensions, 30 minutes at 120 C. Compared to conventional slide agglutination, the slide coagglutination presents more advantages, being simple, rapid, specific and economical.