Usefulness of left atrial volume versus diameter to assess thromboembolic risk in mitral stenosis

Left atrial appendage thrombus with severe mitral stenosis: Responders and non-responders to anticoagulation

INTRODUCTION AND OBJECTIVE

Mitral stenosis (MS) is one of the most frequently observed valvular heart lesions in developing countries and is due to different etiologies. The effects of anticoagulation in different types of left atrial appendage (LAA) are unknown. The current study aimed to determine the resolution of LAA thrombus on transesophageal echocardiography (TEE) after three months of optimal anticoagulation in patients with different types of LAA at baseline cardiac computed tomography of patients with severe MS.

METHODS

This prospective cohort study observed the frequency of LAA thrombus resolution after three months of anticoagulation therapy in patients with severe MS. The response rate in different morphologies of LAA and locations was also assessed. Thrombus resolution after three months of warfarin therapy was assessed on repeat TEE.

RESULTS

A total of 88 patients were included, mean age 37.95±11.87 years. Repeat TEE showed thrombus resolution in only 27.3% of patients. The rate of thrombus resolution was 8/12 (66.7%), 4/28 (14.3%), 8/36 (22.2%), and 4/12 (33.3%) for patients with cactus, cauliflower, chicken wing, and windsock LAA type, respectively. The resolution rate was 0/12 (0%), 4/44 (9.1%), and 20/32 (62.5%) for patients with thrombus in the base, body, and tip of the LAA, respectively.

CONCLUSION

The cactus type of LAA morphology and thrombus at the LAA tip responded well to three months of anticoagulation, however, patients with thrombus in the LAA base and body and cauliflower and chicken wing morphology were non-responders and could benefit from early referral for surgical management.

Atrial fibrillation pattern and factors affecting the progression to permanent atrial fibrillation

Atrial fibrillation (AF) may progress from a non-permanent to a permanent form, and improvement in prediction may help in decision-making. In- and outpatients with non-permanent AF were enrolled in a prospective study and followed every 6 months. At baseline, 314 out of 523 patients (60%) had non-permanent AF (25.5% paroxysmal AF, 52.5% persistent, 2% first diagnosed AF). They were mostly males (188, 59.9%), median age 71 years [interquartile range (IQ) 62-77], median CHA₂DS₂VASc 3 (IQ 1-4), median HATCH score 1 (IQ 1-2). During a follow-up of 701 (IQ 437-902) days, 66 patients (21%) developed permanent AF. CHA₂DS₂VASc and HATCH scores were incrementally associated with AF progression (p for trend CHA₂DS₂VASc < 0.001, HATCH p = 0.001). Cox multivariable proportional hazard regression analysis showed that age [hazard ratio (HR) 1.042; 95%CI 1.005-1.080; p = 0.025], moderate-severe left atrial (LA) enlargement at echo (HR 2.072, 95%CI, 1.121-3.831; p = 0.020), antiarrhythmics drugs (HR 0.087, 95%CI 0.011-0.659, p = 0.018), EHRA score > 2 (HR 0.358, 95%CI 0.162-0.791, p = 0.011) and valvular disease (HR 2.196, 95%CI 1.072-4.499, p = 0.032) were significantly associated with AF progression. Adding "moderate-severe LA dilation" to clinical scores, eg. HATCH score (HATCH-LA) with 2 points (Cox multivariable regression analysis) improved prediction of AF progression vs. HATCH score (p = 0.0225). In patients without permanent AF, progression of AF was independently associated with age, LA dilation, AF symptoms severity, antiarrhythmic drugs and valvular disease. Adding LA dilation (moderate-severe volume increase) to clinical scores improved prediction of progression to permanent AF.

Association of mean platelet volume with echocardiographic findings in patients with severe rheumatic mitral stenosis

Introduction: Rheumatic heart disease (RHD) is a relatively common cause of mortality among patients in the developing countries, and pure mitral valve failure is the most common form of RHD. An increase in the mean platelet volume (MPV) is considered as an independent risk factor for many cardiovascular diseases. This study aimed to evaluate the association of MPV with echocardiographic findings in patients with severe rheumatic mitral stenosis. Methods: In a descriptive, analytical study, 100 patients with severe rheumatic mitral stenosis referred to Shahid Madani hospital of Tabriz University of Medical Sciences and 100 age & sex-matched healthy individuals were included the study. MPV and echocardiographic findings including Wilkins score, left ventricular ejection fraction (LVEF), pulmonary artery systolic pressure, and left atrial spontaneous echo contrast (LASEC) were evaluated in both groups. Results: MPV in the case group was 10.45±0.98 and in the control group was 9.88±0.83. MPV in the patient's groups was significantly higher than the control group (P = 0.001). Also, MPV in patients with positive LASEC findings was 10.69 ± 1.01 and in patients with negative LASEC findings was 10.25 ± 0.91. The difference was found to be statistically significant (P = 0.028). Conclusion: Patients with rheumatic mitral stenosis has a higher MPV compared to the healthy individuals, and it is associated with LASEC sign seen in echocardiography.

On-X mitral valve replacement: a single-centre experience in 318 patients

OBJECTIVES

If mitral valve repair is not feasible, mitral valve replacement remains the only option. Based on our overall experience with the On-X mitral valve, the aim of this study was to investigate early and late outcomes after mitral valve replacement using this latest generation prosthesis.

METHODS

From 1998 to 2016, 600 patients received an On-X prosthesis in the mitral position. Of them, we excluded all patients who had combined aortic procedures and retrospectively analysed 318 consecutive patients who had a mitral valve replacement. Associated procedures (53.5%) were tricuspid valve repair, coronary artery bypass graft and the maze procedure. The mean follow-up time was 5.6 ± 4.0 years.

RESULTS

The overall hospital mortality rate was 4.4%, including acute cases of ischaemic mitral regurgitation (9.4%) and infective endocarditis (9.4%). Survival rates at 1, 3, 5 and 10 years were 97.8 ± 1.0%, 92.4 ± 1.7%, 88.4 ± 2.2% and 70.9 ± 4.0%, respectively. Independent predictors of late mortality were hypertension [hazard ratio (HR) 1.91; P = 0.027], chronic obstructive pulmonary disease (HR 2.91; P = 0.003) and chronic renal failure (HR 5.27; P < 0.001). Freedom from reoperation was 99.3 ± 0.5%, 98.4 ± 0.8%, 97.2 ± 1.2% and 92.5 ± 2.4% at 1, 3, 5 and 10 years, respectively. At follow-up, 8.5% events were recognized as thromboembolic or haemorrhagic events; freedom from events related to anticoagulation therapy at 1, 3, 5 and 10 years was 99.0 ± 0.6%, 96.8 ± 1.1%, 93.7 ± 1.8% and 89.0 ± 2.7%, respectively.

CONCLUSIONS

According to the results of this observational study, the unique design of the On-X valve works well with mitral valve diseases of various aetiologies, especially in cases with an unfavourable anatomy. This prosthesis also guarantees safe long-term durability associated with a low incidence of thromboembolism.

Clinical and echocardiographic characteristics of patients in sinus rhythm, normal left ventricular function, and indeterminate diastolic function

BACKGROUND

Diastolic dysfunction (DDFx) is the major underlying mechanism of heart failure with preserved left ventricular ejection fraction (EF). Yet, the echocardiographic diagnosis of DDFx in patients in sinus rhythm is challenging and up to 25% of studies have discrepant measures making assessment of DDFx indeterminate. We aimed to describe the clinical and echocardiographic characteristics of patients with indeterminate diastolic function compared to patients with definite normal and abnormal diastolic function.

METHODS

One thousand six hundred seventy-four patients were identified from the echocardiography database in sinus rhythm, EF ≥ 45% without wall-motion abnormalities, valvular, congenital heart diseases, cardiomyopathies or pulmonary disease. Patients were divided according to their lateral mitral E/E' ratio and left atrial systolic diameter: normal diastolic function (DFx) (left atrial systolic diameter [LASd] <40 mm, E/E' < 10), DDFx (LASd ≥ 40 mm, E/E' ≥ 10) and indeterminate DFx (discrepant LASd diameter and E/E' ratio).

RESULTS

Clinical and echocardiographic characteristics of the 3 groups, DDFx (n = 186), indeterminate diastolic function (IndtDFx) (n = 207), and normal diastolic function (NDFx) (n = 1281) were significantly different. IndtDFx demonstrated intermediate parameter abnormalities, largely overlapping with DDFx. LASd and E/E' were similarly associated with the inability to determine diastolic function. Age, female gender, renal failure, E/E' and pulmonary pressure were found to be independent predictors of heart failure symptoms (RR = 1.02, 1.5, 2.5, 1.1, 1.1, respectively, P < .0001, r = .35).

CONCLUSION

Clinically and echocardiographically patients with IndtDFx are more closely related to DDfx than to NDFx. Although LAd was abnormal in IndtDFx it was not predictive of heart failure symptoms. Further study is suggested to establish whether LA function rather than its maximal size can provide additional information.

Mitral Valve Replacement-Current and Future Perspectives

The favorable outcomes achieved with modern mitral valve repair techniques redefined the role of mitral valve replacement. Various international databases report a significant decrease in replacement procedures performed compared with repairs, and contemporary guidelines limit the application of surgical mitral valve replacement to pathology in which durable repair is unlikely to be achieved. The progressive paradigm shift toward endoscopic and robotic mitral valve surgery is also paralleled by rapid developments in transcatheter devices, which is progressively expanding from experimental approaches to becoming clinical reality. This article outlines the current role and future perspectives of contemporary surgical mitral valve replacement within the context of mitral valve repair and the dynamic evolution of exciting transcatheter alternatives.

A simple, fast and reproducible echocardiographic approach to grade left ventricular diastolic function

The American Society of Echocardiography and European Association of Echocardiography (ASE/EAE) have published an algorithm for the grading of diastolic function. However, the ability to use this algorithm effectively in daily clinical practice has not been investigated. We hypothesized that in some patients it may be difficult to grade diastolic dysfunction with this scheme, since there may be discrepancies in the assessed parameters. The aim of the current study was to test the feasibility of the ASE/EAE algorithm and to compare this with a new Thoraxcenter (TXC) algorithm. The ASE/EAE and TXC algorithms were applied to 200 patients. The ASE/EAE algorithm starts with assessment of diastolic myocardial wall velocities and left atrial (LA) volumes with subsequent assessment of E/A ratio, E-wave deceleration time and pulmonary venous flow. The TXC algorithm reverses these steps, uses LA dimension instead of volume and does not include a Valsalva manoeuvre and pulmonary venous flow. Due to inconsistencies between diastolic myocardial wall velocities and LA volumes and a not covered E/A ratio in the range of 1.5–2 it was not possible to classify 48 % of patients with the ASE/EAE algorithm, as opposed to only 10 % by the TXC algorithm. LA volume was always needed in the ASE/EAE algorithm. In only 64 % of patients LA size was necessary by the TXC algorithm. When LA volume would have been used instead of LA dimension, grading of LV diastolic function would have been different in only 2 % of patients without apparent improvement. Assessment of LA dimension was considerably faster than LA volume. The TXC algorithm to grade LV diastolic dysfunction was compared to the ASE/EAE algorithm simpler, faster, better reproducible and yields a higher diagnostic outcome.

Echocardiographic measurement of left atrial volume: Does the method matter?

BACKGROUND

Four two-dimensional echocardiographic methods (cube, ellipsoid, Simpson's and area-length) can be used to assess left atrial volume (LAV).

AIMS

To compare absolute LAV measurements and evaluate agreement regarding the semiquantitative assessment of degree of left atrial (LA) enlargement, between methods.

METHODS

We prospectively measured LAV in 51 healthy volunteers using the four methods, and defined thresholds for moderate (mean+2 standard deviations [SDs]) and severe (mean+4 SDs) LA enlargement for each method. In 372 patients referred for echocardiography, we compared absolute LAV measurements and agreement between methods.

RESULTS

LAV was significantly different between methods in the healthy volunteer group (11 ± 4, 17 ± 3, 26 ± 6 and 28 ± 7 mL/m(2), respectively; P<0.0001), resulting in different thresholds for moderate and severe LA enlargement. LAV was also significantly different in the 372 patients (30 ± 20, 47 ± 27, 61 ± 34 and 65 ± 36 mL/m(2), respectively; P<0.0001). Agreement regarding degree of LA enlargement (none, moderate, severe), using the area-length method as reference, was modest with the cube method (kappa=0.41), correct with the ellipsoid method (kappa=0.60) and excellent with Simpson's method (kappa=0.83).

CONCLUSION

The choice of the method had a major effect on assessment of degree of LA enlargement. Our results suggest that the cube and ellipsoid methods, which significantly underestimated LAV and provided modest agreement, should be disregarded. In contrast, Simpson's method and the area-length method were slightly different, but showed close agreement, and should be preferred, using dedicated thresholds (50 and 56 mL/m(2) respectively).

Single breath-hold 3D measurement of left atrial volume using compressed sensing cardiovascular magnetic resonance and a non-model-based reconstruction approach

BACKGROUND

Left atrial (LA) dilatation is associated with a large variety of cardiac diseases. Current cardiovascular magnetic resonance (CMR) strategies to measure LA volumes are based on multi-breath-hold multi-slice acquisitions, which are time-consuming and susceptible to misregistration.

AIM

To develop a time-efficient single breath-hold 3D CMR acquisition and reconstruction method to precisely measure LA volumes and function.

METHODS

A highly accelerated compressed-sensing multi-slice cine sequence (CS-cineCMR) was combined with a non-model-based 3D reconstruction method to measure LA volumes with high temporal and spatial resolution during a single breath-hold. This approach was validated in LA phantoms of different shapes and applied in 3 patients. In addition, the influence of slice orientations on accuracy was evaluated in the LA phantoms for the new approach in comparison with a conventional model-based biplane area-length reconstruction. As a reference in patients, a self-navigated high-resolution whole-heart 3D dataset (3D-HR-CMR) was acquired during mid-diastole to yield accurate LA volumes.

RESULTS

Phantom studies. LA volumes were accurately measured by CS-cineCMR with a mean difference of -4.73 ± 1.75 ml (-8.67 ± 3.54%, r2 = 0.94). For the new method the calculated volumes were not significantly different when different orientations of the CS-cineCMR slices were applied to cover the LA phantoms. Long-axis "aligned" vs "not aligned" with the phantom long-axis yielded similar differences vs the reference volume (-4.87 ± 1.73 ml vs. -4.45 ± 1.97 ml, p = 0.67) and short-axis "perpendicular" vs. "not-perpendicular" with the LA long-axis (-4.72 ± 1.66 ml vs. -4.75 ± 2.13 ml; p = 0.98). The conventional bi-plane area-length method was susceptible for slice orientations (p = 0.0085 for the interaction of "slice orientation" and "reconstruction technique", 2-way ANOVA for repeated measures). To use the 3D-HR-CMR as the reference for LA volumes in patients, it was validated in the LA phantoms (mean difference: -1.37 ± 1.35 ml, -2.38 ± 2.44%, r2 = 0.97). Patient study: The CS-cineCMR LA volumes of the mid-diastolic frame matched closely with the reference LA volume (measured by 3D-HR-CMR) with a difference of -2.66 ± 6.5 ml (3.0% underestimation; true LA volumes: 63 ml, 62 ml, and 395 ml). Finally, a high intra- and inter-observer agreement for maximal and minimal LA volume measurement is also shown.

CONCLUSIONS

The proposed method combines a highly accelerated single-breathhold compressed-sensing multi-slice CMR technique with a non-model-based 3D reconstruction to accurately and reproducibly measure LA volumes and function.

Heme oxygenase derived carbon monoxide and iron mediated plasmatic hypercoagulability in a patient with calcific mitral valve disease

We present a case of a patient with calcific mitral valve stenosis and plasmatic hypercoagulability. Using thrombelastography, the patient was determined to have an abnormally large velocity of plasma thrombus growth and strength with reduced vulnerability to lysis. Critically, increased carboxyhemoglobin concentration (2.4 %) was present, likely secondary to hemolysis from mitral stenosis and engagement of systemic heme oxygenase. It was determined that the patient's plasmatic hypercoagulability was in part due to carboxyhemefibrinogen formation and iron-enhancement of coagulation via two thrombelastographic methods. In conclusion, future investigation of the involvement of both carbon monoxide and iron mediated hypercoagulability in the setting of stenotic valve disease is warranted.

Role of LA shape in predicting embolic cerebrovascular events in mitral stenosis: mechanistic insights from 3D echocardiography

OBJECTIVES

This study was designed to assess the role of left atrial (LA) shape in predicting embolic cerebrovascular events (ECE) in patients with mitral stenosis (MS).

BACKGROUND

Patients with rheumatic MS are at increased risk for ECE. LA remodeling in response to MS involves not only chamber dilation but also changes in the shape. We hypothesized that a more spherical LA shape may be associated with increased embolic events due to predisposition to thrombus formation or to atrial arrhythmias compared with an elliptical-shaped LA of comparable volume.

METHODS

A total of 212 patients with MS and 20 control subjects were enrolled. LA volume, LA emptying fraction, and cross-sectional area were measured by 3-dimensional (3D) transthoracic echocardiography. LA shape was expressed as the ratio of measured LA end-systolic volume to hypothetical sphere volume ([4/3π r(3)] where r was obtained from 3D cross-sectional area). The lower the LA shape index, the more spherical the shape.

RESULTS

A total of 41 patients presented with ECE at the time of enrollment or during follow-up. On multivariate analysis, LA 3D emptying fraction (adjusted odds ratio [OR]: 0.96; 95% confidence interval [CI]: 0.92 to 0.99; p = 0.028) and LA shape index (OR: 0.73; 95% CI: 0.61 to 0.87; p < 0.001) emerged as important factors associated with ECE, after adjustment for age and anticoagulation therapy. In patients in sinus rhythm, LA shape index remained associated with ECE (OR: 0.79; 95% CI: 0.67 to 0.94; p = 0.007), independent of age and LA function. An in vitro phantom atrial model demonstrated more stagnant flow profiles in spherical compared with ellipsoidal chamber.

CONCLUSIONS

In rheumatic MS patients, differential LA remodeling affects ECE risk. A more spherical LA shape was independently associated with an increased risk for ECE, adding incremental value in predicting events beyond that provided by age and LA function.

Efficiency of radiofrequency ablation for surgical treatment of chronic atrial fibrillation in rheumatic valvular disease

BACKGROUND

It remains unclear whether concomitant radiofrequency ablation procedure in valvular surgery could offer additional benefits to patients with rheumatic valvular disease. We designed a prospective and randomized control study to evaluate the efficacy of surgical radiofrequency ablation in patients with rheumatic heart disease.

METHODS

From June 2008 to July 2011, 210 patients with chronic atrial fibrillation and rheumatic heart disease were randomized: (1) control group, patients underwent only valve replacement followed by amiodarone for rhythm control, (2) left atrial group (LA group), patients underwent valve replacement and left atrial mono-polar radiofrequency ablation, (3) bi-atrial group (BA group), patients underwent valve replacement and bi-atrial mono-polar radiofrequency ablation. The primary endpoints included: cardiac death, stroke, and recurrent AF after discharge.

RESULTS

There was no perioperative death. One patient died 4 months after MVR in BA group. In univariate Cox analysis, the two ablation groups were associated with less AF (BA group vs control group: P<0.001; LA group vs control group: P<0.001) as well as atrial tachycardia arrhythmia (AF/AT/AFL) recurrent (BA group vs control group: P<0.001; LA group vs control group: P=0.02). The comparison between BA and LA groups revealed no differences in terms of AF (P=0.06) or AF/AT/AFL (P=0.09). Atrial transport function restoration rate 12 months after operation was 31.4% in LA group, 32.9% in BA group, and 8.6% in control group respectively (P<0.01).

CONCLUSIONS

Radiofrequency ablation concurring with valvular surgery can bring a higher sinus rhythm restoration rate when compared with medical anti-arrhythmic drug therapy in low-medium risk rheumatic heart disease. The trial was registered on Clinicaltrials.gov (registry number NCT01013688).