Viewpoint: the ENIGMAS trial - when should we treat patients with moderate aortic stenosis?

Aortic stenosis (AS) is the most frequent valvular heart disease encountered in our daily practice. Although there are clear guidelines for severe AS management, cardiologists often have few treatment options for patients with moderate AS; however, there is higher mortality in this patient subgroup versus an age-matched population. The authors reviewed all of the studies on moderate AS, summarized the factors that increase disease progression and discussed an ideal trial design to prospectively evaluate AS progression factors using modern cardiology tools such as strain and magnetic resonance imaging.

Speckle tracking echocardiography derived 2-dimensional myocardial strain predicts left ventricular function and mass regression in aortic stenosis patients undergoing aortic valve replacement

Regression of left ventricular (LV) mass in severe aortic stenosis (AS) following aortic valve replacement (AVR) reduces the potential risk of sudden death and congestive heart failure associated with LV hypertrophy. We investigated whether abnormalities of resting LV deformation in severe AS can predict the lack of regression of LV mass following AVR. Two-dimensional speckle tracking echocardiography (STE) was performed in a total of 100 subjects including 60 consecutive patients with severe AS having normal LV ejection fraction (EF > 50 %) and 40 controls. STE was performed preoperatively and at 4 months following AVR, including longitudinal strain assessed from the apical 4-chamber and 2-chamber views and the circumferential and rotational mechanics measured from the apical short axis view. In comparison with controls, the patients with AS showed a significantly lower LV longitudinal (p < 0.001) and circumferential strain (p < 0.05) and higher apical rotation (p < 0.001). Following AVR, a significant improvement was seen in both strains (p < 0.001 for each respectively), however, apical rotation remained unchanged (p = 0.14). On multivariate analysis, baseline LV mass (odds ratio 1.02; p = 0.011), left atrial volume (odds ratio 0.81; p = 0.048) and circumferential strain (odds ratio 0.84; p = 0.02) independently predicted LV mass regression (>10 %) following AVR. In conclusion, STE can quantify the burden of myocardial dysfunction in patients with severe AS despite the presence of normal LV ejection fraction. Furthermore, resting abnormalities in circumferential strain at LV apex is related with a hemodynamic milieu associated with the lack of LV mass regression during short-term follow up after AVR.

Echocardiographic prediction of postoperative atrial fibrillation after aortic valve replacement for aortic stenosis: a two-dimensional speckle tracking left ventricular longitudinal strain multicentre pilot study

BACKGROUND

Postoperative atrial fibrillation (POAF) is a common complication after cardiac surgery, with increased risk of embolic events, haemodynamic instability, haemorrhagic complications and prolonged hospital stay.

AIMS

We sought to assess the value of preoperative left ventricular global longitudinal strain (GLS) for the prediction of POAF in a series of patients with severe symptomatic aortic stenosis who underwent aortic valve replacement (AVR).

METHODS

Fifty-eight consecutive patients (52% men) aged 73±9 years, with severe symptomatic aortic stenosis (aortic valve area<1cm(2) or<0.5cm(2)/m(2)), in sinus rhythm, who underwent AVR were prospectively included in three centres between 2009 and 2010. Complete preoperative echocardiography was performed in all patients, including global and segmental longitudinal strain using two-dimensional speckle tracking.

RESULTS

The POAF incidence was 28/58 (48%). On univariate analysis, aortic valve area (P=0.04), preoperative E/e' ratio (P=0.04) and GLS (P=0.005) were associated with the occurrence of POAF. Chronic obstructive pulmonary disease (P=0.05), preoperative statin treatment (P=0.09), age≥80 years (P=0.09), left ventricular ejection fraction (P=0.09) and systolic pulmonary artery pressure (P=0.06) tended to increase the risk of POAF. The best GLS cut-off value for the prediction of POAF was -15% (82% sensitivity, 53% specificity, area under the curve 0.72). On multivariable analysis, GLS>-15% was the only independent predictor of POAF (odds ratio 7.74, 95% confidence interval [1.15-52.03]; P=0.035).

CONCLUSIONS

Incidence of POAF is high after AVR for severe aortic stenosis. Our results suggest an additive value of the study of left ventricular myocardial deformation to classical clinical and echocardiographic variables for the prediction of POAF in this setting.

Improving assessment of aortic stenosis

"Degenerative" or calcific aortic stenosis is a complex, multifaceted, systemic disease that is not solely limited to the aortic valve but also includes reduced arterial compliance as well as alterations of left ventricular geometry and function. This particular nature of the disease underscores the need for a more comprehensive evaluation of disease severity going beyond the standard parameters routinely used to assess stenosis severity (i.e., peak jet velocity, pressure gradients, valve effective orifice area) or left ventricle function (i.e., left ventricular ejection fraction). The present paper thus proposes to review newer approaches to improve the quantification of disease severity taking into account the interrelation between the different valvular, arterial, and ventricular variables that may be responsible for the appearance of symptoms and/or poorer prognosis in patients with aortic stenosis.

Global Strain in Severe Aortic Valve Stenosis

Background—

Global longitudinal systolic strain (GLS) is often reduced in aortic stenosis despite normal ejection fraction. The importance of reduced preoperative GLS on long-term outcome after aortic valve replacement is unknown.

Methods and Results—

A total of 125 patients with severe aortic stenosis and ejection fraction >40% scheduled for aortic valve replacement were evaluated preoperatively and divided into 4 groups according to GLS quartiles. Patients were followed up for 4 years. The primary end points were major adverse cardiac events (MACEs) defined as cardiovascular mortality and cardiac hospitalization because of worsening of heart failure; the secondary end point was cardiovascular mortality. MACE and cardiac mortality were significantly increased in patients with lower GLS. Estimated 5-year MACE was increased: first quartile 19% (n=6) / second quartile 20% (n=6) / third quartile 35% (n=11) / fourth quartile 49% (n=15); P =0.04. Patients with increased age, left ventricular hypertrophy, and left atrial dilatation were at increased risk. In Cox regression analysis, after correcting for standard risk factors and ejection fraction, GLS was found to be significantly associated with cardiac morbidity and mortality. In a stepwise Cox model with forward selection, GLS was the sole independent predictor: hazard ratio=1.13 (95% confidence interval, 1.02–1.25), P =0.04. Comparing the overall log likelihood χ 2 of the predictive power of the multivariable model containing GLS was statistically superior to models based on EuroScore, history with ischemic heart disease, and ejection fraction.

Conclusions—

In patients with symptomatic severe aortic stenosis undergoing aortic valve replacement, reduced GLS provides important prognostic information beyond standard risk factors.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00294775.

Subclinical left ventricular dysfunction in preeclamptic women with preserved left ventricular ejection fraction: a 2D speckle-tracking imaging study

BACKGROUND

Patients with preeclampsia are at risk for cardiovascular disease. Changes in cardiac function are subtle in preeclampsia and are difficult to quantify with conventional imaging. Strain measurements using speckle-tracking echocardiography have been used to sensitively quantify abnormalities in other disease settings.

METHODS AND RESULTS

We evaluated the feasibility and sensitivity of strain imaging using speckle-tracking echocardiography in women with preeclampsia. Forty-seven women were enrolled in this pilot study and 39 were analyzed: 11 with preeclampsia, 17 without a hypertensive disorder, and 11 with nonproteinuric hypertension. Echocardiographic ejection fraction and global peak longitudinal, radial, and circumferential strain were measured. Longitudinal strain was significantly worsened in women with preeclampsia compared with women without a hypertensive disorder (P=0.0001). Similar results were observed for radial strain (P=0.006) and circumferential strain (P=0.03). Women with preeclampsia also had significantly worsened longitudinal (P=0.04), radial (P=0.01), and circumferential (P=0.002) strain compared with women with nonproteinuric hypertension. Women with preeclampsia did not have a significantly different ejection fraction compared with women without a hypertensive disorder (P=0.16) and women with nonproteinuric hypertension (P=0.44).

CONCLUSIONS

Myocardial strain imaging using speckle tracking is more sensitive than left ventricular ejection fraction to detect differences in left ventricular systolic function in women with and without preeclampsia.

Global longitudinal strain is a strong independent predictor of all-cause mortality in patients with aortic stenosis

AIMS

To assess the capacity of global longitudinal strain (GLS) in patients with aortic stenosis (AS) to (i) detect the subclinical left ventricular (LV) dysfunction [LV ejection fraction (LVEF) ≥50% patients]; (ii) predict all-cause mortality and major adverse cardiac events (MACE) (all patients), and (iii) provide incremental prognostic information over current risk markers.

METHODS AND RESULTS

Patients with AS (n = 146) and age-matched controls (n = 12) underwent baseline echocardiography to assess AS severity, conventional LV parameters and GLS via speckle tracking echocardiography. Baseline demographics, symptom severity class and comorbidities were recorded. Outcomes were identified via hospital record review and subject/physician interview. The mean age was 75 ± 11, 62% were male. The baseline aortic valve (AV) area was 1.0 ± 0.4 cm(2) and LVEF was 59 ± 11%. In patients with a normal LVEF (n = 122), the baseline GLS was controls -21 ± 2%, mild AS -18 ± 3%, moderate AS -17 ± 3% and severe AS -15 ± 3% (P< 0.001). GLS correlated with the LV mass index, LVEF, AS severity, and symptom class (P< 0.05). During a median follow-up of 2.1 (inter-quartile range: 1.8-2.4) years, there were 20 deaths and 101 MACE. Unadjusted hazard ratios (HRs) for GLS (per %) were all-cause mortality (HR: 1.42, P< 0.001) and MACE (HR: 1.09, P< 0.001). After adjustment for clinical and echocardiographic variables, GLS remained a strong independent predictor of all-cause mortality (HR: 1.38, P< 0.001).

CONCLUSIONS

GLS detects subclinical dysfunction and has incremental prognostic value over traditional risk markers including haemodynamic severity, symptom class, and LVEF in patients with AS. Incorporation of GLS into risk models may improve the identification of the optimal timing for AV replacement.

[Assessment of left ventricular twist mechanics by two-dimensional strain in severe aortic stenosis with preserved ejection fraction]

Left ventricular (LV) twist is increased in aortic stenosis (AS) and the hypothesis of a compensatory mechanism is suggested but not established. Our aim was to assess LV twist mechanics in severe AS (<1cm(2) or 0.6cm(2)/m(2)) with preserved LV ejection fraction (LVEF>50%), and to analyze its relationship with LV systolic longitudinal function, early impaired in this setting, LV diastolic function, and symptomatic status.

METHODS

Forty-five consecutive patients with severe AS and preserved LVEF (mean age 73±11 years, 47% female, LVEF 68±11%, 67% symptomatic) underwent a transthoracic echocardiography including a bidimensional strain analysis by speckle tracking method, and were compared to a control group matched for age and sex (n=15). Global longitudinal strain (GLS) was measured using the four, two, and three apical views, and LV twist mechanics from the basal and apical short axis views. LV twist was defined as the net difference between apical and basal rotation, and LV twisting and untwisting rate (in°/s) were derived from twist curves.

RESULTS

Peak apical rotation, LV twist (25±8° vs 20±6), as well as peak systolic and diastolic apical rotation rate, and peak LV twisting rate were significantly higher in patients with AS when compared to controls (all, P<0.05), whereas, the other parameters of LV twist mechanics including basal rotation, were not significantly different between groups. By contrast, the GLS was significantly lower in patients with AS when compared to controls (-17.9±4 vs -20.5±2%, P<0.01). In addition, the GLS was significantly correlated to LV torsion (r=-0.42, P<0.01). Moreover, LV twist progressively impaired with the worsening of diastolic dysfunction and with symptoms onset.

CONCLUSION

LV twist is increased in severe AS with preserved LVEF, compensating the impairment of systolic longitudinal function. However, above a certain threshold LV twist deteriorates, attesting the failure of the compensatory mechanisms, leading to advanced diastolic dysfunction and symptom onset.