Altered trans-mitral flow velocity pattern after exercise predicts development of new-onset atrial fibrillation in elderly patients with impaired left ventricular relaxation at rest: Prognostic value of diastolic stress echocardiography

Influence of the flow split ratio on the position of the main atrial vortex: Implications for stasis on the left atrial appendage

BACKGROUND

Despite the recent advances in computational fluid dynamics (CFD) techniques applied to blood flow within the left atrium (LA), the relationship between atrial geometry, flow patterns, and blood stasis within the left atrial appendage (LAA) remains unclear. A better understanding of this relationship would have important clinical implications, as thrombi originating in the LAA are a common cause of stroke in patients with atrial fibrillation (AF).

AIM

To identify the most representative atrial flow patterns on a patient-specific basis and study their influence on LAA blood stasis by varying the flow split ratio and some common atrial modeling assumptions.

METHODS

Three recent techniques were applied to nine patient-specific computational fluid dynamics (CFD) models of patients with AF: a kinematic atrial model to isolate the influence of wall motion because of AF, projection on a universal LAA coordinate system, and quantification of stagnant blood volume (SBV).

RESULTS

We identified three different atrial flow patterns based on the position of the center of the main circulatory flow. The results also illustrate how atrial flow patterns are highly affected by the flow split ratio, increasing the SBV within the LAA. As the flow split ratio is determined by the patient's lying position, the results suggest that the most frequent position adopted while sleeping may have implications for the medium- and long-term risks of stroke.

Echocardiographic predictors of cardioembolic stroke due to underlying atrial fibrillation: Reliable left atrial remodeling signs in acute stroke

INTRODUCTION

Atrial remodeling due to high-burden atrial fibrillation (AF) is associated with cardioembolic stroke (CES). As not all CESs is caused by AF, we analyzed the diagnostic values of each echocardiographic parameter to distinguish likely AF-related CES in acute stroke patients while in non-AF rhythm.

METHODS

The data of consecutive patients with acute ischemic stroke in sinus rhythm between 2012 and 2015 were obtained. The echocardiographic parameters of patients with CES due to underlying AF (n = 61) and control patients (n = 319) with either large artery atherosclerosis or small-vessel occlusion were compared using receiver operating characteristic curves and logistic regression analyses. Each parameter was reassessed in acute stroke patients through a validation study using the same database with different periods of generalization.

RESULTS

CES patients with underlying AF showed a significantly larger left atrial volume index (LAVi), higher mitral inflow E wave (E), and lower A wave (A) than the controls. The area under the curve (AUC) (95% confidence interval) for diagnosing CES due to underlying AF was significantly higher for LAVi/A than for LAVi (0.785 versus 0.696, P < 0.01). Among patients aged >60 years, the E/A ratio had the highest AUC (0.857) of the parameters. The cut-off values were ≥ 0.70 (sensitivity, 55.7%; specificity, 90.9%) and ≥ 0.82 (sensitivity, 71.4%; specificity, 84.1%) for LAVi/A and the E/A ratio, respectively, in patients >60 years. The cut-off values of all parameters showed similar trends in a validation study.

CONCLUSION

LAVi/A is a useful indicator for distinguishing CES patients with underlying AF regardless of age, and the E/A ratio is reliable among patients aged >60 years in evaluation during acute stroke admission.

Prognostic significance of exercise-induced diastolic dysfunction: A systematic review

BACKGROUND

Recent guidelines recommend diastolic stress testing among patients with unexplained dyspnea. Previous studies have reported exercise related change in diastolic parameters as a prognostic marker for worse outcomes. However, the role of exercise-induced diastolic dysfunction (DD) in predicting adverse outcomes has not been fully established.

METHOD

We conducted a meta-analysis to explore the prognostic significance of exercise-induced DD. PUBMED/EMBASE/SCOPUS databases were searched for studies reporting adverse outcomes in patients undergoing exercise echocardiography based on diastolic response during exercise. Exercise-induced DD was defined as an increase in E/e' or E/A ratio with stress. Outcomes of interest were cardiovascular mortality or hospitalizations.

RESULTS

A total of 8 studies were identified, including 4,462 patients who underwent exercise stress echocardiography. The follow-up ranged from 13 months to 5 years. The major indication for stress testing was exertional dyspnea. All studies reported cardiac mortality and hospitalization in the composite outcome. Meta-analysis conducted using random-effects model showed that exercise-induced DD was associated with a higher likelihood of cardiovascular mortality or hospitalization (HR = 1.32, P < .05). Significant heterogeneity was noted among the studies.

CONCLUSIONS

Exercise-induced DD is associated with worse cardiovascular outcomes. Changes in echocardiographic parameters such as e' with exercise might be useful for risk stratification and identification of high-risk patients.

Evaluation of left atrial function by speckle tracking echocardiography in patients with systemic lupus erythematosus

Left atrial (LA) function plays a key role in maintaining optimal cardiac output. Left ventricular diastolic dysfunction (LVDD) has been reported in systemic lupus erythematosus (SLE), but whether LA functional abnormalities also occur in patients with SLE is unknown. Toward this aim we evaluated left atrial function and volume by strain and strain rate derived from speckle tracking echocardiography (STE) and their associations with LVDD. Sixty SLE patients were compared with age- and gender-matched normal controls. The LA strain (S) and strain rate (SR) during systole, early diastole and late diastole (SRs, SRe and SRa, respectively) were measured by STE. The LA volume index (LAVI), traditional parameters of LA and left ventricular diastolic function also were analysed. Global strain and positive SRe were significantly reduced in the SLE group compared with the control group (26.2% ± 9.5% vs 32.5% ± 9.8% and −2.4 ± 1.0 s−1 vs −3.1 ± 1.2 s−1, both p < 0.05). The SRs in the SLE and control groups were not significantly different (2.1 ± 0.7 s−1 vs 2.4 ± 0.8 s−1, p = 0.2). The positive SRa was increased in the SLE group compared with the control group (−2.1 ± 0.8 s−1 vs −1.6 ± 0.5 s−1, p < 0.05) and the LAVI was larger in the SLE group than in the control group (32.4 ± 8.0 vs 25.8 ± 7.1 ml/m2, p < 0.001). Patients with SLE exhibiting varying grades of LVDD displayed significant differences in LA parameters, including LAVI, SRs, SRe and SRa (all p < 0.05). Multivariate linear analysis additionally revealed that SLICC/ACR damage index (SDI) was independently and inversely associated with global strain, SRs and positive SRe. LA functions were changed in SLE patients, demonstrating impairment in conduit function, decrease in storage function and increase in pump function. Meanwhile, the magnitude of this impairment was predictively associated with the severity of LVDD. The results from this study demonstrate that STE is capable of detecting various aspects of LA functional impairment during SLE progression, and should be further explored as a diagnostic tool for improving the outcomes of SLE patients.

Elevated left ventricular filling pressure estimated by E/E' ratio after exercise predicts development of new-onset atrial fibrillation independently of left atrial enlargement among elderly patients without obvious myocardial ischemia

OBJECTIVE

To determine whether elevated left ventricular (LV) filling pressure estimated by raised Doppler E velocity to tissue Doppler E' velocity ratio (E/E') after exercise is associated with increased risk of new-onset atrial fibrillation (AF) in non-ischemic elderly patients.

BACKGROUND

Prognostic importance of exercise induced LV diastolic dysfunction remains uncertain.

PATIENTS AND METHODS

We studied 147 elderly patients (73 ± 5 years) who underwent treadmill stress echocardiography. Patients with exercise induced LV wall motion abnormality were not included. Doppler and tissue Doppler measurements were done before treadmill exercise and immediately after the post-stress image acquisition, and E/E' ratio was measured. Raised E/E' was defined as E/E'≥ 15, and left atrial (LA) enlargement was defined as LA volume index ≥ 34 ml/m(2). Using Cox proportional hazards regression analysis, predictor of new-onset AF was determined. Using Kaplan-Meier analysis, we evaluated association between raised post-exercise E/E' or LA enlargement with new-onset AF.

RESULTS

During the follow-up period (median=67 months), there were 25 new-onset AF. Cox proportional hazards regression analysis demonstrated that male gender [hazard ratio (HR) 3.294; p=0.0117], LA enlargement (HR 3.576; p=0.0017), and raised post-exercise E/E' (HR 3147; p=0.0068) were the best predictors of new-onset AF. Kaplan-Meier survival plot demonstrated that patients with both LA enlargement and raised post-exercise E/E' developed new-onset AF most frequently. There was no significant difference in outcome between patients with isolated raised post-exercise E/E' or isolated LA enlargement.

CONCLUSIONS

Raised E/E' ratio after exercise provides significant prognostic information for predicting new-onset AF in non-ischemic elderly patients. This prognostic value of raised post-exercise E/E' is independent of and incremental to the LA enlargement.