Transmural compensation of myocardial deformation to preserve left ventricular ejection performance in chronic aortic regurgitation

Cardiac remodeling and antihypertensive medication changes after thoracic endovascular aortic repair vs open surgical repair

OBJECTIVE

Cardiovascular complications remain one of the major all-cause mortalities among patients who receive either thoracic endovascular aortic repair (TEVAR) or open surgical repair (OSR). Increased aortic stiffness after endograft deployment has been shown to induce left ventricular hypertrophy, diastolic dysfunction, and reduced coronary flow reserve. However, there is limited data on the hemodynamic effects after OSR. The purpose of this study is to compare the cardiovascular and hemodynamic changes after TEVAR and OSR.

METHODS

A retrospective analysis of 100 patients with thoracic aortic aneurysm or dissection who underwent open (n = 50) or endovascular repair (n = 50) was conducted. Information on demographics, medical and surgical history, and clinical outcomes were retrieved. Transthoracic echocardiographic imaging results were collected to assess cardiac function. Changes to antihypertensive medication dosage and number were used as surrogate markers for hemodynamic changes and aortic stiffness.

RESULTS

No statistically significant differences were observed in antihypertensive medication number or dosage between the TEVAR and OSR group at 12 months, 24 months, and 36 months post-surgery. When adjusting for patient demographic factors of age, sex, and body surface area in a multivariable generalized estimating equation model, patients who underwent TEVAR had a higher likelihood of receiving more antihypertensive medications (incidence rate ratio [IRR], 1.131; P = .044). Patient characteristics such as body surface area (IRR, 1.266; P = .001), hypertension (IRR, 2.070; P ≤ .001), diabetes mellitus (IRR, 1.474; P ≤ .001), and end-stage renal disease (IRR, 1.304; P = .011) were also associated with a higher number of antihypertensive medications. A significant increase in beta-blockers (P ≤ .001) and diuretics (P = .046) intake was observed post-TEVAR and post-OSR. No significant differences in left ventricular ejection fraction and left ventricular hypertrophy were observed between the two groups.

CONCLUSIONS

We observed a greater likelihood of antihypertensive medications escalation following TEVAR, suggesting an increase in aortic stiffness postoperatively. No significant differences in cardiac remodeling were observed between the two groups. Our findings emphasize the need for an improved postoperative cardiac surveillance program in patients undergoing both TEVAR and OSR. Furthermore, additional innovation is needed to create aortic grafts that are more compatible with the native aorta to reduce long-term cardiovascular complications.

Echocardiographic assessment of aortic regurgitation: a narrative review

Aortic regurgitation (AR) is the third most frequently encountered valve lesion and may be caused by abnormalities of the valve cusps or the aorta. Echocardiography is instrumental in the assessment of AR as it enables the delineation of valvular morphology, the mechanism of the lesion and the grading of severity. Severe AR has a major impact on the myocardium and carries a significant risk of morbidity and mortality if left untreated. Established and novel echocardiographic methods, such as global longitudinal strain and three-dimensional echocardiography, allow an estimation of this risk and provide invaluable information for patient management and prognosis. This narrative review summarises the epidemiology of AR, reviews current practices and recommendations with regards to the echocardiographic assessment of AR and outlines novel echocardiographic tools that may prove beneficial in patient assessment and management.

Layer-specific longitudinal strain detects transmural dysfunction in chronic severe aortic regurgitation before and after aortic valve surgery

To assess if layer-specific longitudinal strain (LS) provides incremental diagnostic and prognostic value compared to global longitudinal strain (GLS) in patients with chronic severe aortic regurgitation (AR) scheduled for aortic valve surgery. Forty-one patients were examined with speckle tracking echocardiography before surgery along with 15 healthy age-matched controls. Paired strain analyses before and after surgery were available in 31 patients. Layer-specific LS analysis enabled assessment of epicardial GLS (GLSepi), endocardial GLS (GLSendo), and conventional GLS. Strain parameters were indexed to end-diastolic volume (EDV; GLS/EDV) to account for increased preload. The prognostic value of layer-specific LS was evaluated using the primary outcome of persistent LV dilatation (LVEDV ≥ 175 mL) three months after surgery. Absolute (GLS, GLSepi, GLSendo) and EDV-indexed layer-specific LS (GLS/EDV, GLSepi/EDV, GLSendo/EDV) were impaired in severe AR compared to controls at baseline (GLS:17.0 ± 3.2 vs. 20.6 ± 2.0; GLSepi:14.6 ± 2.8 vs. 18.1 ± 1.9; GLSendo:20.2 ± 3.7 vs. 23.8 ± 2.2%; GLS/EDV:0.09 ± 0.05 vs. 0.21 ± 0.05; GLSepi/EDV:0.08 ± 0.04 vs. 0.18 ± 0.04; GLSendo/EDV:0.11 ± 0.06 vs. 0.24 ± 0.05%/mL; all p < 0.001). In severe AR, GLS, GLSepi and GLSendo decreased after surgery whereas GLS/EDV, GLSepi/EDV and GLSendo/EDV increased (all p < 0.001). Impaired absolute and EDV-indexed layer-specific LS were all associated with the primary outcome (all p ≤ 0.01). Area under the curve analysis revealed similar prognostic value of GLSepi, GLSendo and GLS (GLS:0.86; GLSepi:0.87; GLSendo:0.86; p = n.s.). EDV-indexed LS did not improve the predictive value significantly (GLS/EDV:0.93; GLSepi/EDV: 0.93; GLSendo/EDV:0.92; p = n.s.). Layer-specific LS detects transmural dysfunction in chronic severe AR and predicts persistent LV dilation after surgery. Layer-specific LS or EDV-indexed LS does not provide incremental prognostic value compared to conventional GLS.

Impact of chronic kidney disease on clinical outcomes in patients with Stage B progressive aortic regurgitation (mild to moderate and moderate grades)

Background

Chronic kidney disease (CKD) is a significant comorbidity in patients with heart failure and valvular heart disease. Renal impairment is not well evaluated in the patients with Stage B progressive aortic regurgitation (AR) (mild to moderate and moderate grades in this study), for estimating outcome.

Hypothesis

We sought to investigate the prognostic factor, especially CKD, in the patients with progressive AR.

Methods

We enrolled 262 patients with Stage B progressive AR and preserved left ventricular systolic function (ejection fraction ≥ 50%). Based on the presence of CKD, the patients were divided into CKD (n = 70) and non‐CKD (n = 192) groups, which CKD was defined as estimated glomerular filtration rate < 60 ml/min/1.73 m². The primary outcome was major adverse cardiac events (MACEs), including cardiac death, myocardial infarction, hospitalization for heart failure, and aortic valve replacement.

Results

The median follow‐up duration was 41.5 (interquartile range: 16.2–71.7) months. Between groups, the CKD patients were older; they had a higher pulse pressure and higher incidence of hypertension, diabetes mellitus, dyslipidemia, cerebrovascular accident, and atrial fibrillation. Compared to the non‐CKD group, the CKD group had lower eʹ velocity (4.36 ± 2.21 vs. 5.20 ± 2.30 cm/s, p = .009), higher right ventricular systolic pressure (38.02 ± 15.79 vs. 33.86 ± 11.77 mmHg, p = .047). The CKD group was associated with increased risk of MACEs (41.4% vs. 22.4%; unadjusted hazard ratio [HR]: 1.78, 95% confidence interval [CI]: 1.11–2.85, p = .017). In multivariate Cox regression analyses, the risk of MACEs was significantly different between groups (adjusted HR: 1.71, 95% CI: 1.11–2.62, p = .015); furthermore, the risk of hospitalization for heart failure (10.0% vs. 2.6%; adjusted HR: 2.30, 95% CI: 1.16–4.55, p = .017) was significantly higher in the CKD group than in the non‐CKD group.

Conclusions

In patients with Stage B progressive AR, CKD is an independent prognostic factor for clinical outcomes (composite clinical outcome, hospitalization for heart failure).

Chronic kidney disease is a known comorbidity for valvular heart disease.

We investigated that chronic kidney disease was an independent prognostic factor for clinical outcomes (composite clinical outcome and hospitalization for heart failure) in patients with Stage B progressive aortic regurgitation.

Although Stage B progressive aortic regurgitation should be carefully monitored in all patients by guideline, special attention should be paid to patients with pre‐existing chronic kidney disease.

Speckle-Tracking Echocardiography for Detecting Subclinical Left Ventricular Dysfunction in Patients With Familial Hypercholesterolemia

Myocardial ischemia and left ventricular dysfunction have been documented in young adults with familial hypercholesterolemia. We investigated whether speckle-tracking echocardiography can be used to detect subclinically impaired global and regional myocardial function in patients with this lipid disorder. This single-center study included 47 patients with familial hypercholesterolemia and 37 healthy control subjects who underwent transthoracic Doppler echocardiography and speckle-tracking echocardiography from January 2003 through December 2016. Conventional echocardiographic and strain parameters in the 2 groups were analyzed and compared. Left ventricular dimensions were significantly larger at end-diastole (P=0.02) and end-systole (P=0.013), left ventricular walls were significantly thicker (P <0.0001), and the early transmitral/early diastolic mitral annular velocity ratio was significantly higher (P=0.006) in the patient group than in the control group. In the patient group, global longitudinal and circumferential strain values were significantly lower (P <0.0001) and global radial strain values significantly higher (P=0.006); all segmental longitudinal strain (P <0.04) and most segmental circumferential strain values (P ≤0.01) were significantly lower; and some segmental radial strains, especially at the apex, were significantly higher (P ≤0.04). However, average longitudinal, circumferential, and radial strains in the different segments of the 3 main coronary artery territories were significantly lower in the patient group (P <0.01). Global longitudinal strain (r=0.561; P=0.001) and global circumferential strain (r=0.565; P <0.0001) were inversely correlated with low-density-lipoprotein cholesterol levels. We conclude that speckle-tracking echocardiography can be used to detect subclinical global and regional systolic abnormalities in patients with familial hypercholesterolemia.

Left ventricular systolic function impairment in children after balloon valvuloplasty for congenital aortic stenosis assessed by 2D speckle tracking echocardiography

AIMS

The aim of the study was to evaluate left ventricular (LV) remodeling and systolic function using two-dimensional speckle tracking echocardiographic (2D STE) imaging in children at a long-term (more than 36 months, 107.5±57.8 months) after balloon valvuloplasty for aortic stenosis (BAV).

METHODS AND RESULTS

40 patients (mean age 9,68 years, 75% male) after BAV and 62 control subjects matched to the age and heart rate were prospectively evaluated. The 2D STE assessment of LV longitudinal and circumferential strain and strain rate was performed. Left ventricular eccentric hypertrophy (LVEH) was diagnosed in 75% of patients in the study group. Left ventricular ejection fraction (LVEF) was normal in all patients. In study group, global longitudinal strain (GLS), global longitudinal strain rate (GLSr) were significantly lower compared with the controls: GLS (-19.7±2.22% vs. -22.3±1.5%, P< 0.001), GLSr (-0.89±0.15/s vs. -1.04 ±0.12/s, P < 0.001). Regional (basal, middle and apical segments) strain and strain rate were also lower compared with control group. Global circumferential strain (GCS), global circumferential strain rate (GCSr) as well as regional (basal, middle and apical segments) strain and strain rate were normal. Multivariable logistic regression analysis included: instantaneous peak systolic Doppler gradient across aortic valve (PGmax), grade of aortic regurgitation (AR), left ventricular mass index (LVMI), left ventricular relative wall thickness (LVRWT), left ventricular end-diastolic diameter (LVEDd), peak systolic mitral annular velocity of the septal and lateral corner (S'spt, S'lat), LVEF before BAV and time after BAV and showed that the only predictor of reduced GLS was LV eccentric hypertrophy [odds ratio 6.9; (95% CI: 1.37-12.5), P = 0.045].

CONCLUSION

Patients at long-term observation after BAV present the subclinical LV systolic impairment, which is associated with the presence of its remodeling. Longitudinal deformation is the most sensitive marker of LV systolic impairment in this group of patients.

Impact of Mitral Surgery for Mitral Regurgitation on Coexisting Aortic Regurgitation

Background: There is no clear finding on the course of coexisting aortic regurgitation (AR) after treatment of mitral regurgitation (MR). We investigated the effect of mitral surgery for MR on coexisting AR.

Methods: Between January 2008 and December 2016, 75 patients underwent mitral surgery for MR coexisting mild AR. Of these, 65 patients who were available to follow-up postoperative echocardiographic tests 1 year after surgery were included in the present study. Patients were divided into two groups according to the degree of postoperative AR. We investigated the predictive factors for continued AR and perioperative cardiac function.

Results: In all, 22 patients’ AR improved and became less than mild and 43 patients’ persisted at mild or increased. The predictive factor for continued AR was left atrial diameter >50 mm (P = 0.021, odds ratio = 4.739, 95% confidence interval: 1.259–17.846) in multivariate logistic regression analysis. No patients underwent reoperation for continued AR in both groups. However, one patient was rehospitalized for heart failure in the continued AR group.

Conclusion: Left atrial diameter may be an important prognostic factor for continued AR after mitral surgery for MR. MR with mild AR should be treated as soon as before the left atrium expands.

Newer echocardiographic techniques for aortic-valve imaging: Clinical aids today, clinical practice tomorrow

Increasing life expectancy is expected to lead to a corresponding increase in the prevalence of aortic valve disease (AVD). Further, the number of indications for transcatheter aortic valve replacement (TAVR) as a treatment option for AVD is expanding, with a growing role for echocardiography in its management. In this review we summarize the current literature on some newer echocardiographic modalities and the parameters they generate, with a particular focus on their prognostic and clinical value beyond conventional methods in the management of aortic stenosis, TAVR, and aortic regurgitation. Speckle tracking and 3D echocardiography are now increasingly being used in the management of AVD. For instance, global longitudinal strain, the best-studied speckle tracking echocardiographic parameter, can detect subtle subclinical cardiac dysfunction in patients with AVD that is not apparent using traditional echocardiographic techniques. The emerging technique of 3D full volume color Doppler echocardiography provides more accurate measurement of the severity of aortic regurgitation than 2D-proximal isovelocity surface area. These novel techniques are promising for evaluating and risk stratifying patients to optimize surgical interventions, predict recovery, and improve clinical outcomes.

Detection of subclinical left ventricular dysfunction by tissue Doppler imaging in horses with aortic regurgitation

BACKGROUND

Aortic regurgitation (AR) can have an important clinical impact and in some cases leads to left ventricular (LV) failure. Tissue Doppler imaging (TDI) is an echocardiographic technique that has been used in horses to detect LV dysfunction.

OBJECTIVES

To examine whether TDI detects changes in radial myocardial wall motion in horses with AR compared with control horses.

STUDY DESIGN

Case-control study.

METHODS

Echocardiography was performed in 30 healthy Warmblood horses and 34 Warmblood horses with AR, subdivided in groups with mild, moderate or severe AR. TDI measurements were performed on six segments of the short-axis images of the LV myocardial wall. Myocardial wall motion was evaluated by measuring velocity and deformation during isovolumetric contraction, systole, early and late diastole. Timing of different events was also measured.

RESULTS

In most segments, a significantly higher systolic myocardial velocity was found in horses with AR compared with controls. Horses with AR also had higher late diastolic velocity, although the difference was not significant in all segments. TDI measurement of timing intervals demonstrated less difference between groups.

MAIN LIMITATIONS

There was a significant difference in age between the control group and horses with AR, which may confound the results. The assessment of AR severity was based on subjective criteria as there is no gold standard.

CONCLUSIONS

TDI showed significant differences in radial systolic and late diastolic myocardial velocity in horses with AR. This could indicate an altered LV function in these horses, but further research is needed to investigate the prognostic value of these measurements.

Exploratory assessment of left ventricular strain-volume loops in severe aortic valve diseases

KEY POINTS

Severe aortic valve diseases are common cardiac abnormalities that are associated with poor long-term survival. Before any reduction in left ventricular (LV) function, the left ventricle undergoes structural remodelling under the influence of changing haemodynamic conditions. In this study, we combined temporal changes in LV structure (volume) with alterations in LV functional characteristics (strain, ԑ) into a ԑ-volume loop, in order to provide novel insight into the haemodynamic cardiac consequences of aortic valve diseases in those with preserved LV ejection fraction. We showed that our novel ԑ-volume loop and the specific loop characteristics provide additional insight into the functional and mechanical haemodynamic consequences of severe aortic valve diseases (with preserved LV ejection fraction). Finally, we showed that the ԑ-volume loop characteristics provide discriminative capacity compared with conventional measures of LV function.

ABSTRACT

The purpose of this study was to examine left ventricular (LV) strain (ԑ)-volume loops to provide novel insight into the haemodynamic cardiac consequences of aortic valve stenosis (AS) and aortic valve regurgitation (AR). Twenty-seven participants were retrospectively recruited: AR (n = 7), AS (n = 10) and control subjects (n = 10). Standard transthoracic echocardiography was used to obtain apical four-chamber images to construct ԑ-volume relationships, which were assessed using the following parameters: early systolic ԑ (ԑ_ES); slope of ԑ-volume relationship during systole (Sslope); end-systolic peak ԑ (peak ԑ); and diastolic uncoupling (systolic ԑ-diastolic ԑ at same volume) during early diastole (UNCOUP_ED) and late diastole (UNCOUP_LD). Receiver operating characteristic curves were used to determine the ability to detect impaired LV function. Although LV ejection fraction was comparable between groups, longitudinal peak ԑ was reduced compared with control subjects. In contrast, ԑ_ES and Sslope were lower in both pathologies compared with control subejcts (P < 0.01), but also different between AS and AR (P < 0.05). UNCOUP_ED and UNCOUP_LD were significantly higher in both patient groups compared with control subjects (P < 0.05). Receiver operating characteristic curves revealed that loop characteristics (AUC = 0.99, 1.00 and 1.00; all P < 0.01) were better able then peak ԑ (AUC = 0.75, 0.89 and 0.76; P = 0.06, <0.01 and 0.08, respectively) and LV ejection fraction (AUC = 0.56, 0.69 and 0.69; all P > 0.05) to distinguish AS vs control, AR vs control and AS vs AR groups, respectively. Temporal changes in ԑ-volume characteristics provide novel insight into the haemodynamic cardiac impact of AS and AR. Contrary to traditional measures (i.e. ejection fraction, peak ԑ), these novel measures successfully distinguish between the haemodynamic cardiac impact of AS and AR.

Incremental Value of Two Dimensional Speckle Tracking Echocardiography in the Functional Assessment and Characterization of Subclinical Left Ventricular Dysfunction

Subclinical left ventricular (LV) dysfunction refers to subtle abnormalities in LV function which typically precede a reduction in the left ventricular ejection fraction (LVEF). The assessment of myocardial function using LVEF, a radial metric of systolic function, is subject to load dependence, intra-observer and inter-observer variability. Reductions in LVEF typically manifest late in the disease process thus compromising the ability to intervene before irreversible impairment of systolic performance sets in. 2-Dimensional speckle tracking echocardiography (2D-STE), a novel strain imaging modality has shown promise as a sensitive indicator of myocardial contractility. It arms the clinician with a powerful and practical tool to rapidly quantify cardiac mechanics, circumventing several inherent limitations of conventional echocardiography. This article highlights the incremental utility of 2D-STE in the detection of subclinical LV dysfunction.

Left Ventricular Contraction Pattern in Chronic Aortic Regurgitation and Preserved Ejection Fraction: Simultaneous Stress-Strain Analysis by Three-Dimensional Echocardiography

BACKGROUND

The role of speckle-tracking echocardiography in the assessment of chronic aortic regurgitation (AR) is not established. Load dependency may encumber the interpretation of strain measurements in the chronically overloaded left ventricle. The aim of this study was to investigate the mechanisms of left ventricular (LV) contraction patterns in asymptomatic patients with moderate to severe AR and preserved ejection fractions.

METHODS

In this prospective, cross-sectional study, 31 patients with moderate to severe AR, 15 elite endurance athletes, and 17 healthy control subjects were examined using three-dimensional speckle-tracking echocardiography. Global circumferential strain (GCS), global longitudinal strain (GLS), end-systolic circumferential wall stress (ESSc), end-systolic meridional wall stress (ESSm), and the wall stress ratio (ESSc/ESSm) were measured.

RESULTS

LV end-diastolic volumes were similar in athletes and patients with AR and significantly larger than in healthy control subjects. Values of GLS in control subjects, athletes, and patients with AR were -18.8 ± 1.9%, -17.3 ± 2.0%, and -16.4± 2.0%, respectively (control subjects vs athletes and patients, P < .05), whereas values of GCS were -16.9 ± 2.0%, -15.5 ± 1.9%, and -17.9 ± 2.6%, respectively (athletes vs control subjects and patients, P < .01). The ESSc/ESSm ratio was lower in patients with AR (P < .01). When adjusted for ESSm, GLS remained impaired in patients compared with control subjects and athletes (P = .015). On the other hand, GCS was better in patients with AR when adjusted for ESSc (P = .003).

CONCLUSIONS

In compensated AR, relatively high GCS compensates for reduced GLS in a manner consistent with the preserved ejection fractions observed in these patients.

Left ventricular reverse remodeling after aortic valve surgery for acute versus chronic aortic regurgitation

AIMS

Extent of left ventricular (LV) reverse remodeling after aortic valve repair or replacement (AVR) may differ between patients operated for acute aortic regurgitation (AR) and chronic AR. The aim of this study was to compare changes in LV volumes and function between patients with acute and chronic AR who underwent AVR.

METHODS AND RESULTS

A total of 98 patients (54±15 years, 61% men) with acute (n=21) or chronic AR (n=77) were included in the present retrospective evaluation. LV volumes, LV ejection fraction, and global longitudinal strain indexed for LV end-diastolic volume (GLSi) were assessed preoperatively and after a median follow-up of 28 months (interquartile range: 17-66 months). Patients with acute AR tended to have smaller preoperative LV end-diastolic volume compared with chronic AR (156±15 vs 183±6 mL; P=.070). Both in patients with acute and chronic AR, significant LV reverse remodeling with sustained reduction in LV volumes occurred during follow-up with a significant smaller LV end-diastolic volume in acute AR compared with chronic AR (106±8 vs 128±5 mL; P=.032). Preoperative and postoperative LV ejection fractions were not significantly different between groups. In contrast, GLSi was better in patients with acute AR compared with chronic AR before AVR (-1.34±0.20 vs -0.96±0.07%/10 mL; P=.042) and during follow-up (-1.65±0.16 vs -1.29±0.07%/10 mL; P=.017).

CONCLUSIONS

After AVR, LV reverse remodeling occurs both in patients with acute and chronic AR. However, LV end-diastolic volume was more reduced and GLSi was more preserved during follow-up in acute AR than in chronic AR.

Recent advances in echocardiography for valvular heart disease

Echocardiography is the imaging modality of choice for the assessment of patients with valvular heart disease. Echocardiographic advancements may have particular impact on the assessment and management of patients with valvular heart disease. This review will summarize the current literature on advancements, such as three-dimensional echocardiography, strain imaging, intracardiac echocardiography, and fusion imaging, in this patient population.

Left Ventricular Strain as Predictor of Chronic Aortic Regurgitation

BACKGROUND

It is not well known about the implication of left ventricular (LV) strain as a predictor for mortality in patients with chronic aortic regurgitation (AR). The purpose of this study was to investigate whether global longitudinal strain measured by two-dimensional speckle-tracking echocardiography could predict long-term outcome in patients with chronic AR.

METHODS

This is a single center non-randomized retrospective observational study. The patients with chronic AR from January 2002 to December 2012 were retrospectively enrolled. Following patients were excluded; combined other significant valvular disease, previous heart surgery, aortic disease, congenital heart disease, acute AR and young age under 18 years old. Finally, 60 patients were analyzed and the LV global strain rate was measured on apical four chamber image (GS-4CH).

RESULTS

During 64 months follow-up duration, 16 patients (26.7%) were deceased and 38 patients (63.3%) underwent aortic valve replacement (AVR). Deceased group was older (69 years old vs. 51 years old, p < 0.001) and had lower longitudinal strain (-12.05 ± 3.72% vs. -15.66 ± 4.35%, p = 0.005). Kaplan-Meier survival curve stratified by GS-4CH showed a trend of different event rate (log rank p = 0.001). On multivariate analysis by cox proportional hazard model adjusting for age, sex, body surface area, history of atrial fibrillation, blood urea nitrogen, LV dilatation, LV ejection fraction and AVR, decreased GS-4CH proved to be an independent predictor of mortality in patients with chronic AR (hazard ratio 1.313, 95% confidence interval 1.010-1.706, p = 0.042).

CONCLUSION

GS-4CH may be a useful predictor of mortality in patient with chronic AR.

Effects of Bone Marrow Mononuclear Cells Delivered through a Graft Vessel for Patients with Previous Myocardial Infarction and Chronic Heart Failure: An Echocardiographic Study of Left Ventricular Function

OBJECTIVES

The graft of stem cells to treat ischemic cardiomyopathy is popular in many clinical trials. The aim of this study was to evaluate the effectiveness of isolated coronary artery bypass graft combined with bone marrow mononuclear cells (BMMNC) delivered through graft vessels to improve left ventricular function of patients with previous myocardial infarction and chronic heart failure using echocardiography.

METHODS

Forty-two patients with previous myocardial infarction and chronic heart failure were randomly allocated to one of the two groups: CABG only (18 in CABG group), or CABG with BMMNC transplantation (24 in CABG + BMMNC group). Echocardiographic parameters of systolic function were measured on B-mode imaging, tissue Doppler imaging (TDI), two-dimensional (2D) strain imaging, and 8 parameters were measured totally. Echocardiographic parameters of diastolic function were measured on pulsed-wave Doppler imaging, TDI, and 2D strain rate imaging; 17 parameters were measured totally.

RESULTS

Postoperative left ventricular ejection fraction (LVEF) versus preoperative LVEF were 49.083 ± 1.914% versus 36.042 ± 1.185% (P < 0.05) in CABG + BMMMNC group and 41.389 ± 2.210% versus 34.667 ± 1.369% (P < 0.05) in CABG group, global longitudinal strain were -12.542 ± 0.512% versus -7.083 ± 0.583% (P < 0.05) in CABG + BMMMNC group and -9.278 ± 0.591% versus -7.000 ± 0.673% (P < 0.05) in CABG group, mLsr1 were -0.108 ± 0.018/sec versus -0.039 ± 0.017/sec (P < 0.05) in CABG+BMMMNC group and -0.048 ± 0.021/sec versus 0.004 ± 0.020/sec (P < 0.05) in CABG group, mLsr2 were -0.055 ± 0.013/sec versus -0.009 ± 0.015/sec (P < 0.05) in CABG + BMMMNC group and 0.004 ± 0.015/sec versus 0.024 ± 0.017/sec (P < 0.05) in CABG group, and Aa1 were 7.303 ± 0.479 cm/sec versus 5.131 ± 0.381 cm/sec (P < 0.05) in CABG + BMMMNC group and 7.908 ± 0.553 cm/sec versus 6.764 ± 0.440 cm/sec (P < 0.05) in CABG group. Parameters above were significantly improved postoperatively in both groups. The degree of the improvement was significantly different between the two groups with the CABG + BMMNC group improved more versus the group of CABG only (P < 0.05).

CONCLUSIONS

The improvement of left ventricular function in CABG + BMMNC group is better than CABG group. 2D strain and strain rate imaging is a more sensitive tool to evaluate left ventricular function.

Association of hypercholesterolemia and cardiac function evaluated by speckle tracking echocardiography in a rabbit model

Background

Although hypercholesterolemia is a major risk factor for coronary artery disease (CAD), only limited data are available regarding its direct effect on myocardial function apart from CAD. The aim of this study was to evaluate LV systolic function using speckle-tracking echocardiography and investigate the relationship between hypercholesterolemia and myocardial function.

Methods

Twenty-eight rabbits were randomly divided into three groups: 8 were fed normal chow for 3 months (group 1) and the remaining 20 were fed an atherogenic diet for 2 (group 2) or 3 months (group 3). Global systolic radial, circumferential and longitudinal peak strain were calculated. Serum total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and myocardial cholesterol levels were measured.

Results

Global systolic longitudinal strain were both decreased in the group 2 and 3 (P < 0.001), whereas radial strain were increased (P < 0.001) compared with group 1. Global circumferential strain in the group 3 was significantly reduced (P < 0.001). Serum and myocardial cholesterol concentration markedly increased in the group 2 and group 3 (P < 0.001). There was a significant inverse correlation between longitudinal strain and serum TC, LDL-C as well as myocardial cholesterol levels (r = - 0.723, r = - 0.794, r = - 0.700, P both < 0.001). A significant negative correlation was also noted between circumferential strain and serum TC, LDL-C as well as myocardial cholesterol levels (r = - 0.518, P = 0.007; r = - 0.691, P < 0.001; r = - 0.659, P < 0.001). A significant positive correlation was found between radial strain and serum TC, LDL-C as well as myocardial cholesterol levels (r = 0.432, P = 0.028; r = 0.602, P = 0.001; r = 0.469, P = 0.016).

Conclusion

Although LV morphology and ejection fractions were not different among the three groups, elevated concentration of cholesterol, especially in serum LDL-C, was significantly associated with LV systolic dysfunction. The findings also indicate that reductions in longitudinal was the first appeared, followed by circumferential, and was compensated for by increasing radial strain.

Perioperative assessment of myocardial deformation

Evaluation of left ventricular performance improves risk assessment and guides anesthetic decisions. However, the most common echocardiographic measure of myocardial function, the left ventricular ejection fraction (LVEF), has important limitations. LVEF is limited by subjective interpretation that reduces accuracy and reproducibility, and LVEF assesses global function without characterizing regional myocardial abnormalities. An alternative objective echocardiographic measure of myocardial function is thus needed. Myocardial deformation analysis, which performs quantitative assessment of global and regional myocardial function, may be useful for perioperative care of surgical patients. Myocardial deformation analysis evaluates left ventricular mechanics by quantifying strain and strain rate. Strain describes percent change in myocardial length in the longitudinal (from base to apex) and circumferential (encircling the short-axis of the ventricle) direction and change in thickness in the radial direction. Segmental strain describes regional myocardial function. Strain is a negative number when the ventricle shortens longitudinally or circumferentially and is positive with radial thickening. Reference values for normal longitudinal strain from a recent meta-analysis by using transthoracic echocardiography are (mean ± SD) -19.7% ± 0.4%, while radial and circumferential strain are 47.3% ± 1.9% and -23.3% ± 0.7%, respectively. The speed of myocardial deformation is also important and is characterized by strain rate. Longitudinal systolic strain rate in healthy subjects averages -1.10 ± 0.16 s. Assessment of myocardial deformation requires consideration of both strain (change in deformation), which correlates with LVEF, and strain rate (speed of deformation), which correlates with rate of rise of left ventricular pressure (dP/dt). Myocardial deformation analysis also evaluates ventricular relaxation, twist, and untwist, providing new and noninvasive methods to assess components of myocardial systolic and diastolic function. Myocardial deformation analysis is based on either Doppler or a non-Doppler technique, called speckle-tracking echocardiography. Myocardial deformation analysis provides quantitative measures of global and regional myocardial function for use in the perioperative care of the surgical patient. For example, coronary graft occlusion after coronary artery bypass grafting is detected by an acute reduction in strain in the affected coronary artery territory. In addition, assessment of left ventricular mechanics detects underlying myocardial pathology before abnormalities become apparent on conventional echocardiography. Certainly, patients with aortic regurgitation demonstrate reduced longitudinal strain before reduction in LVEF occurs, which allows detection of subclinical left ventricular dysfunction and predicts increased risk for heart failure and impaired myocardial function after surgical repair. In this review, we describe the principles, techniques, and clinical application of myocardial deformation analysis.

Decision Making in Asymptomatic Aortic Regurgitation in the Era of Guidelines

Background—

The decision-making role of exercise echocardiography in the surgical timing for aortic regurgitation remains a matter of debate because of limited data on its link with outcome. The aim of this study was to assess the role of echocardiographic measurements at rest and during exercise as predictors of valve surgery in asymptomatic aortic regurgitation.

Methods and Results—

Comprehensive resting and exercise echocardiography was performed in 159 consecutive patients (50±15 years; 80% male) with isolated moderately severe to severe aortic regurgitation and preserved left ventricular (LV) function (LV ejection fraction >50%, LV end-diastolic dimension ≤70 mm, LV end-systolic dimension ≤50 mm or ≤25 mm/m 2 ) in whom initial management was expectant. Echocardiographic measurements were performed at rest and during exercise. LV and right ventricular (RV) longitudinal strain was analyzed at rest using velocity vector imaging. Valve surgery was performed in 50 patients (31%) during 30±21 months. After adjustment for age and sex in a multivariable Cox proportional-hazards model, exercise tricuspid annular plane systolic excursion (TAPSE; hazards ratio [HR], 0.48; P =0.001) was associated with valve surgery-free, independent of resting LV strain (HR, 1.63; P =0.005), exercise LV end-diastolic volume (HR, 1.38; P =0.048), and resting RV strain (HR, 1.69; P =0.002). In sequential Cox models, a model based on clinical data (χ 2 , 20.4) was improved by resting LV strain (χ 2 , 30.1; P =0.001), resting RV strain (χ 2 , 49.7; P <0.001), and further increased by exercise TAPSE (χ 2 , 64.4; P <0.001).

Conclusions—

In asymptomatic aortic regurgitation, resting LV strain, resting RV strain, and exercise TAPSE were independently associated with the need for earlier aortic surgery.

Prognostic value of cardiac magnetic resonance imaging in patients with aortic regurgitation

Guidelines on valve replacement recommend aortic valve replacement for patients with severe aortic regurgitation (AR) with symptoms or left ventricular (LV) dysfunction. However, the optimal timing of surgery for asymptomatic AR patients without LV dilation or dysfunction is not known. There are data to suggest that excess volume load imposed by AR may not only produce subclinical LV dysfunction, but produce neurohormonal activation similar to the heart failure syndrome resulting in reduced survival. The study by Myerson et al. is the first to investigate the predictive ability of cardiac MRI (CMR) for the outcome of asymptomatic patients with AR. They studied 113 asymptomatic patients with moderate-to-severe AR on echocardiography in four centers. A total of 39 (35%) patients developed symptoms or an indication for surgery over a mean follow-up period of 2.6 years. AR volume, AR regurgitant fraction, LV end-diastolic and end-systolic volumes had high discriminatory powers (area under curve of 0.96, 0.93, 0.88 and 0.78, respectively) to predict these events. Higher association with the outcome was observed when LV end-diastolic volume and regurgitant fraction were combined. A significantly higher number of patients with regurgitant fraction >33% were likely to progress to surgery compared with patients with a regurgitant fraction of <33% (85 vs 8%; p < 0.001). These results demonstrate a potential role for CMR for risk stratification of patients with asymptomatic moderate or severe AR, given the ability of CMR to accurately quantify AR and LV volumes. Based on the data presented, it is possible that we may be waiting too long to offer surgery in patients with severe AR.

Usefulness of bidimensional strain imaging for predicting outcome in asymptomatic patients aged ≤ 16 years with isolated moderate to severe aortic regurgitation

Aortic regurgitation (AR) has increased in the pediatric population because of the expanded use of new surgical and hemodynamic procedures. Unfortunately, the exact timing for operation in patients with AR is still debated. Conventional echocardiographic parameters, left ventricular (LV) dimensions and the LV ejection fraction, have limitations in predicting early LV dysfunction. Two-dimensional strain imaging, an emerging ultrasound technology, has the potential to better study those patients. The aim of this study was to assess the prognostic value of 2-dimensional longitudinal strain in young patients with congenital isolated moderate to severe AR. Twenty-six young patients with asymptomatic AR (aged 3 to 16 years) were studied. The mean follow-up duration was 2.9 ± 1.2 years (range 0.5 to 6). Baseline LV function by speckle-tracking and conventional echocardiography in patients with stable disease was compared with that in patients with progressive AR (defined as development of symptoms, increase in LV volume ≥15%, or decrease in the LV ejection fraction ≤10% during follow-up). LV ejection fractions were similar between groups. The jet area/LV outflow tract area ratio was significantly increased in patients with AR with progressive disease (31.2 ± 5.6% vs 39.2 ± 3.8%, p <0.001). The peak transmitral early velocity/early diastolic mitral annular velocity ratio was significantly increased in patients with progressive AR (p = 0.001). LV average longitudinal strain was significantly reduced in patients with progressive AR compared to those with stable AR (-17.8 ± 3.9% vs -22.7 ± 2.7%, p = 0.001). On multivariate analysis, the only significant risk factor for progressive AR was average LV longitudinal strain (p = 0.04, cut-off value >-19.5%, sensitivity 77.8%, specificity 94.1%, area under the curve 0.889). In conclusion, 2-dimensional strain imaging can discriminate young asymptomatic patients with progressive AR. This could allow young patients with AR to have a better definition of surgical timing before the occurrence of irreversible myocardial damage.