Left Atrial Phasic Function and Its Association With Atrial Fibrillation in Patients After Transcatheter Aortic Valve Implantation

Prognostic value of left atrial strain in aortic stenosis: A systematic review

PURPOSE

Aortic stenosis (AS) is a common valvular heart disease with high morbidity and mortality. Recently, the association between peak atrial longitudinal strain (PALS) and AS clinical outcomes has been identified. This systematic review evaluates the prognostic value of PALS for adverse events in AS.

METHODS

We performed a systematic literature review to identify clinical studies that evaluated Speckle-Tracking Echocardiography (STE)-derived PALS to predict adverse outcomes in patients with AS. We excluded studies that compared echocardiography to computed tomography and studies that focused on diseases other than AS.

RESULTS

We included 18 studies reporting on 2660 patients. Patients with symptomatic AS had decreased PALS when compared to patients with asymptomatic AS. Patients with AS who had adverse events had decreased PALS when compared to patients with AS with no events. Each unit increase of PALS was independently associated with decreased risk for the primary endpoint. PALS cut-off values were associated with increased risk for the primary endpoint.

CONCLUSION

This systematic review suggests PALS as an independent predictor for cardiovascular events in patients with AS and highlights the importance of evaluating LA mechanics for AS prognosis.

The influence of transcatheter aortic valve replacement on left atrial mechanics: a systematic review and meta-analysis

Aims

The morphology and function of the left atrium (LA) are intimately tied to left ventricular loading conditions. Data pertaining to the effect of transcatheter aortic valve replacement (TAVR) on LA function and geometry are scarce. The aim of the study was to quantify associations between TAVR and LA remodelling by pooling available data from published observational studies.

Methods and results

A systematic review and meta-analysis were performed. Studies reporting serial LA speckle-tracking echocardiographic (STE) data, before and after TAVR, were included. Other outcome data included LA area and indexed volume (LAVi) and standard chamber measurements. Outcomes were stratified by timing of follow-up echocardiography: early (<6 months) or late (≥6 months). Twelve studies were included, comprising 1066 patients. The mean reduction in LAVi was 2.72 mL/m2 [95% confidence interval (CI) 1.37-4.06, P < 0.01]. LA reservoir function improved overall by a mean difference (MD) of 3.71% (95% CI 1.82-5.6, P < 0.01), although there was significant heterogeneity within the pooled studies (I 2 = 87.3%). Significant improvement in reservoir strain was seen in both early follow-up (MD 3.1%, P < 0.01) and late follow-up studies (MD 4.48%, P = 0.03), but heterogeneity remained high (I 2 = 65.23 and 94.4%, respectively). Six studies reported a change in LA contractile function, which recovered in the early follow-up studies (MD 2.26, P < 0.01), but not in the late group (MD 1.41, P = 0.05). Pooled improvement in LA booster function was 1.96% (95% CI 1.11-2.8, P < 0.01).

Conclusion

TAVR is associated with significant negative LA remodelling, and an improvement in LA mechanics, quantified by STE. The prognostic implications of these findings require further study.

Left atrial pump strain predicts long-term survival after transcatheter aortic valve implantation

BACKGROUND

This study aims at investigating left atrial (LA) deformation by left atrial reservoir (LARS) and pump strain (LAPS) and its implications for long-term survival in patients with severe aortic stenosis (AS) undergoing transcatheter aortic valve implantation (TAVI).

METHODS

Speckle tracking echocardiography was performed in 198 patients with severe AS undergoing TAVI. Association of strain parameters with cardiovascular mortality was determined.

RESULTS

Over a follow-up time of 5 years, 49 patients (24.7%) died. LAPS was more impaired in non-survivors than survivors (P = 0.010), whereas no difference was found for LARS (P = 0.114), LA ejection fraction (P = 0.241), and LA volume index (P = 0.292). Kaplan-Meier analyses yielded a reduced survival probability according to the optimal threshold for LAPS (P = 0.002). A more impaired LAPS was associated with increased mortality risk (HR 1.12 [95% CI 1.02-1.22]; P = 0.014) independent of LVEF, LAVI, age, and sex. Addition of LAPS improved multivariable echocardiographic (LVEF, LAVI) and clinical (age, sex) models with potential incremental value for mortality prediction (P = 0.013 and P = 0.031, respectively). In contrast, LARS and LAVI were not associated with mortality.

CONCLUSIONS

In patients undergoing aortic valve replacement for severe AS, LAPS was impaired in patients dying during long-term follow-up after TAVI, differentiated survivors from non-survivors, was independently associated with long-term mortality, and yielded potential incremental value for survival prediction after TAVI. LAPS seems useful for risk stratification in severe AS and timely valve replacement.

Hemodynamic implications of mitral annular calcification in patients undergoing transcatheter aortic valve implantation for severe aortic stenosis

PURPOSES

Predicting hemodynamic changes of stenotic mitral valve (MV) lesions with mitral annular calcification (MAC) following transcatheter aortic valve implantation (TAVI) may inform clinical decision-making. This study aimed to investigate the association between the MAC severity quantified by computed tomography (CT) and changes in mean transmitral gradient (mTMG), mitral valve area (MVA) and stroke volume index (SVi) following TAVI.

METHODS AND RESULTS

A total of 708 patients (median age 81, 52% male) with severe aortic stenosis (AS) underwent pre-procedural CT and pre- and post-TAVI transthoracic echocardiography. According to the classification of MAC severity determined by CT, 299 (42.2%) patients had no MAC, 229 (32.3%) mild MAC, 102 (14.4%) moderate MAC, and 78 (11.0%) severe MAC. After adjusting for age and sex, there was no significant change in mTMG following TAVI (Δ mTMG = 0.07 mmHg, 95% CI -0.10 to 0.23, P = 0.92) for patients with no MAC. In contrast, patients with mild MAC (Δ mTMG = 0.21 mmHg, 95% CI 0.01 to 0.40, P = 0.018), moderate MAC (Δ mTMG = 0.31 mmHg, 95% CI 0.02 to 0.60, P = 0.019) and severe MAC (Δ mTMG = 0.43 mmHg, 95% CI 0.10 to 0.76, P = 0.0012) had significant increases in mTMG following TAVI, with greater changes associated with increasing MAC severity. In contrast, there was no significant change in MVA or SVi following TAVI.

CONCLUSION

In patients with severe AS undergoing TAVI, MAC severity was associated with greater increases in post-procedural mTMG whereas MVA or SVi remained unchanged. MAC severity should be considered for potential subsequent MV interventions if TAVI does not improve symptoms.

Atrial Cardiomyopathy in Valvular Heart Disease: From Molecular Biology to Clinical Perspectives

This review discusses the evolving topic of atrial cardiomyopathy concerning valvular heart disease. The pathogenesis of atrial cardiomyopathy involves multiple factors, such as valvular disease leading to atrial structural and functional remodeling due to pressure and volume overload. Atrial enlargement and dysfunction can trigger atrial tachyarrhythmia. The complex interaction between valvular disease and atrial cardiomyopathy creates a vicious cycle of aggravating atrial enlargement, dysfunction, and valvular disease severity. Furthermore, atrial remodeling and arrhythmia can predispose to atrial thrombus formation and stroke. The underlying pathomechanism of atrial myopathy involves molecular, cellular, and subcellular alterations resulting in chronic inflammation, atrial fibrosis, and electrophysiological changes. Atrial dysfunction has emerged as an essential determinant of outcomes in valvular disease and heart failure. Despite its predictive value, the detection of atrial fibrosis and dysfunction is challenging and is not included in the clinical routine. Transthoracic echocardiography and cardiac magnetic resonance imaging are the main diagnostic tools for atrial cardiomyopathy. Recently published data have revealed that both left atrial volumes and functional parameters are independent predictors of cardiovascular events in valvular disease. The integration of atrial function assessment in clinical practice might help in early cardiovascular risk estimation, promoting early therapeutic intervention in valvular disease.

Strain Echocardiography to Predict Postoperative Atrial Fibrillation

Postoperative atrial fibrillation (POAF) complicates 15% to 40% of cardiovascular surgeries. Its incidence progressively increases with aging, reaching 50% in octogenarians. This arrhythmia is usually transient but it increases the risk of embolic stroke, prolonged hospital stay, and cardiovascular mortality. Though many pathophysiological mechanisms are known, POAF prediction is still a hot topic of discussion. Doppler echocardiogram and, lately, strain echocardiography have shown significant capacity to predict POAF. Alterations in oxidative stress, calcium handling, mitochondrial dysfunction, inflammation, fibrosis, and tissue aging are among the mechanisms that predispose patients to the perfect "atrial storm". Manifestations of these mechanisms have been related to enlarged atria and impaired function, which can be detected prior to surgery. Specific alterations in the atrial reservoir and pump function, as well as atrial dyssynchrony determined by echocardiographic atrial strain, can predict POAF and help to shed light on which patients could benefit from preventive therapy.

Utility of Functional and Volumetric Left Atrial Parameters Derived From Preprocedural Cardiac CTA in Predicting Mortality After Transcatheter Aortic Valve Replacement

Background: Cardiac CTA is required for preprocedural workup before transcatheter aortic valve replacement (TAVR) and can be used to assess functional parameters of the left atrium (LA). Objective: We aimed to evaluate the utility of functional and volumetric LA parameters derived from cardiac CTA to predict mortality in patients with severe aortic stenosis (AS) undergoing TAVR. Methods: This retrospective study included 175 patients with severe AS (median age 79 years; 92 male, 83 female) who underwent cardiac CTA for clinical pre-TAVR assessment. A postdoctoral research fellow calculated maximum and minimum LA volumes using biplane area-length measurements; the values were indexed to body surface area (LAVImax and LAVImin, respectively). LA emptying fraction (LAEF) was automatically calculated. All-cause mortality within a 24-month follow-up period post-TAVR was recorded. To identify parameters predictive of mortality, Cox regression was performed, and results were summarized by hazard ratio (HR) and 95% CI. Harrell's c-index was used to assess model performance. A radiology resident repeated the measurements in a random sample of 20% (n=35) of cases, and interobserver agreement was computed using the intraclass correlation coefficient (ICC). Results: Thirty-eight deaths (22%) were recorded within a median follow-up of 21 months. LAVImax (HR 1.02 [1.01-1.04]; p=.005), LAVImin (HR 1.02 [1.01-1.04]; p<.001), and LAEF (HR 0.97 [0.95-0.99]; p=.002) were predictive of mortality in univariable analysis. After adjusting for clinical parameters, only LAEF (HR 0.97 [0.94-0.99]; p=.02) independently predicted mortality. The c-index of the Society of Thoracic Surgeons Predicted Risk of Mortality (STS-PROM) significantly increased from 0.64 to 0.68, 0.69, and 0.70 when incorporating into the model LAVImax, LAVImin, and LAEF, respectively. ICC for maximum and minimum LA volumes and LAEF ranged from 0.94 to 0.99. Conclusion: LAEF derived from preprocedural cardiac CTA independently predicts mortality in patients with severe AS undergoing TAVR. Clinical impact: Cardiac CTA-derived LA function, evaluated during pre-TAVR workup, can be used to assess preprocedural risk and may improve risk stratification in post-TAVR surveillance.

Long-term implications of left atrial appendage thrombus identified incidentally by pre-procedural cardiac computed tomography angiography in patients undergoing transcatheter aortic valve replacement

AIMS

The prevalence and prognostic implications of left atrial appendage (LAA) thrombus (LAAT) in patients considered for transcatheter aortic valve replacement (TAVR) are incompletely defined. We, therefore, studied pre-procedural cardiac computed tomography angiography (CCTA) scans of TAVR candidates to determine the prevalence of LAAT and its association with late outcomes.

METHODS AND RESULTS

Baseline clinical variables and CCTA findings from a prospective TAVR registry were analysed for the prevalence of pre-procedural LAAT and its impact on in-hospital outcomes and late mortality. LAAT was differentiated from LAA filling defects (LAAFD) reflecting stasis without clot. Patients (n = 561) with complete in-hospital and late mortality data were included in the study (median follow-up 31.6 months). LAAT and LAAFD were evidenced on pre-procedural CCTA in 24 (4.3%) and 26 (4.6%) patients, respectively. One hundred fourteen (20.3%) patients died during the study period. Though in-hospital adverse event rates (including stroke) did not differ among groups, mortality at long-term follow-up was higher among LAAT patients compared with those with or without LAAFD (58.3% vs. 11.5% vs. 19.0%, respectively; P < 0.003). By multivariable analysis, LAAT (but not LAAFD) was independently associated with all-cause mortality [hazard ratio (HR) = 3.33 (1.83-6.00), P < 0.001]. In patients with LAAT, oral anticoagulation at discharge was associated with lower mortality risk, independently of atrial fibrillation status.

CONCLUSIONS

LAAT visualized by pre-procedural CCTA is an independent predictor of late mortality following TAVR, but not peri-procedural stroke. When reporting TAVR-CCTA, particular note should be made of LAA features and presence of LAAT which may have prognostic and management implications.

New Onset Atrial Fibrillation Following Transcatheter and Surgical Aortic Valve Replacement: A Systematic Review and Meta-Analysis

BACKGROUND

New-onset atrial fibrillation (NOAF) is a well-recognised, although variably reported complication following surgical aortic valve replacement (SAVR). Rates of NOAF following transcatheter aortic valve implantation (TAVI) seem to be notably less than SAVR, even though this population is typically older and of higher risk. The aim of this study was to determine the prevalence of NOAF in both these populations and associated postoperative outcomes.

METHODS

We conducted a systematic review and meta-analysis of studies reporting rates of NOAF post SAVR or TAVI, along with early postoperative outcomes. Twenty-five (25) studies with a total of 13,010 patients were included in the final analysis.

RESULTS

The prevalence of NOAF post SAVR was 0.4 (95% CI 0.36-0.44) and post TAVI 0.15 (95% CI 0.11-0.18). NOAF was associated with an increased risk of postoperative cerebrovascular accident (CVA) for SAVR and TAVI (RR 1.44 95% CI 1.01-2.06 and RR 2.24 95% CI 1.46-3.45 respectively). NOAF was associated with increased mortality in the TAVI group (RR 3.02 95% CI 1.55-5.9) but not the SAVR group (RR 1.00, 95% CI 0.54-1.84). Hospital length of stay was increased for both TAVI and SAVR patients with NOAF (MD 2.54 days, 95% CI 2.0-3.00) and (MD 1.64 days, 95% CI 0.04-3.24 respectively).

CONCLUSIONS

The prevalence of NOAF is significantly less following TAVI, as compared to SAVR. While NOAF is associated with increased risk of postoperative stroke for both groups, for TAVI alone NOAF confers increased risk of early mortality.

Clinical implication of disturbed left atrial phasic functions in the heterogeneous population associated with hypertension or atrial fibrillation

BACKGROUND

To evaluate left atrial (LA) phasic functions in patients with hypertension and/or paroxysmal atrial fibrillation (PAF) and its clinical significance.

METHODS

LA strain was studied in 77 patients (25 hypertension, 24 lone AF, and 28 with both hypertension and PAF) and 28 controls using two-dimensional speckle-tracking echocardiography (2D STE). The following indexes during atrial reservoir, conduit and pump phase were analyzed respectively: (1) peak atrial longitudinal strain (PALS) and strain rate (PALSR), (2) the standard deviation of time to PALS and PALSR of all LA segments (TpS-SD% and TpSR-SD%).

RESULTS

Compared with controls, PALS_res, PALS_cond and PALSR_cond were significantly reduced in patients with isolated hypertension (all P < 0.01) but no significant differences were observed in PALS_pump, PALSR_pump and TpS_pump-SD% between them (all P > 0.05). PALS_pump, PALSR_pump and PALSR_res were significantly lower in patients with both hypertension and PAF than in those with isolated hypertension (all P < 0.05). PALS and PALSR were significantly decreased, and TpS-SD% was significantly increased during each phase in lone AF patients than in controls (all P < 0.05), and PALSR_pump was further depressed in patients with both hypertension and PAF (P = 0.029). PALSR_cond ≤ 1.475 s^- 1 combined with TpS_pump-SD% ≥ 3.25% (sensitivity, 85%; specificity, 71%; AUC = 0.845, P < 0.001) could distinguish lone AF from healthy subjects effectively, while in hypertensive patients, PALS_pump ≤ 14.2% was found to be an independent differentiator for occurrence of AF or not with sensitivity of 81% and specificity of 84% (AUC = 0.838, P < 0.001). LAVI≥29.3 mL/m² was an independent characteristic for reflecting different LA remodeling in lone AF or hypertension with AF.

CONCLUSIONS

The impairment of LA phasic functions was varied in patients with hypertension and/or AF. The disturbed LA phasic functions were proved to have independent abilities of differential diagnosis in this heterogeneous population associated with hypertension or AF.