Determinants and prognostic implications of left ventricular mechanical dispersion in aortic stenosis

Predominant determinants for evaluation of right parasternal approach in transthoracic echocardiography in aortic stenosis: a study based on three-dimensional cardiac computed tomography analysis

The maximum blood flow velocity through the aortic valve (AVmax) using Doppler transthoracic echocardiography (TTE) is important in assessing the severity of aortic stenosis (AS). The right parasternal (RP) approach has been reported to be more useful than the apical approach, but the anatomical rationale has not been studied. We aimed to clarify the influence of the angle formed by the ascending aorta and left ventricle on Doppler analysis by TTE (Sep-Ao angle) and three-dimensional multidetector computed tomography (3D-MDCT) in patients with AS. A total of 151 patients evaluated using the RP approach and 3D-MDCT were included in this study. The Sep-Ao angle determined using TTE was compared with that determined using 3D-MDCT analysis. In MDCT analysis, the left ventricular (LV) axis was measured in two ways and the calcification score was calculated simultaneously. The Sep-Ao angle on TTE was consistent with that measured using 3D-MDCT. In patients with an acute Sep-Ao angle, the Doppler angle in the apical approach was larger, potentially underestimating AVmax. Multivariate analysis revealed that an acute Sep-Ao angle, large Doppler angle in the apical approach, smaller Doppler angle in the RP approach, and low aortic valve calcification were independently associated with a higher AVmax in the RP approach than in the apical approach. The Sep-Ao angle measured using TTE reflected the 3D anatomical angle. In addition to measurements using the RP approach, technical adjustments to minimize the Doppler angle to avoid bulky calcification should always be noted for accurate assessment.

Left ventricular mechanical dispersion as a predictor of the need for pacemaker implantation after transcatheter aortic valve implantation: MeDiPace TAVI study

AIMS

Permanent pacemaker (PM) implantation is common after transcatheter aortic valve implantation (TAVI). Left ventricular mechanical dispersion (MeDi) by speckle tracking echocardiography is a marker of fibrosis that causes alterations in the conduction system. We hypothesized that MeDi can be a predictor of the need for PM implantation after TAVI.

METHODS AND RESULTS

Consecutively, 200 TAVI patients were enrolled. Transthoracic echocardiography and electrocardiography examinations were recorded before TAVI to evaluate global longitudinal strain (GLS), MeDi, and conduction disturbances. PM implantation information was obtained 3 months after TAVI. Patients were stratified into PM or no PM group. Mean age was 80 + 7 years (44% women). Twenty-nine patients (16%) received PM. MeDi, QRS duration, existence of right bundle branch abnormality (RBBB), and first-degree atrioventricular (AV) block were significantly different between groups. MeDi was 57 ± 15 ms and 48 ± 12 ms in PM and no PM groups, respectively (P < 0.001). In multivariate analysis, MeDi predicted the need for PM after TAVI independently of GLS, QRS duration, RBBB, and first-degree AV block [odds ratio (OR): 1.73, 95% confidence interval (CI): 1.22-2.45] with an area under the curve (AUC) of 0.68 in receiver operating characteristic (ROC) curves. Moreover, RBBB was an independent predictor of PM need after TAVI (OR: 8.98, 95% CI: 1.78-45.03). When added to RBBB, MeDi had an incremental predictive value with an AUC of 0.73 in ROC curves (P = 0.01).

CONCLUSION

MeDi may be used as an echocardiographic functional predictor of the need for PM after TAVI.

Additive Prognostic Value of Left Ventricular Dispersion and Deformation in Patients With Severe Aortic Stenosis

BACKGROUND

Speckle tracking strain echocardiography allows one to visualize the timing of maximum regional strain and quantifies left ventricular-mechanical dispersion (LV-MD). Whether LV-MD and LV-global longitudinal strain (LV-GLS) provide similar or complementary information in mortality risk stratification in patients with severe aortic stenosis (SAS) remains unknown.

OBJECTIVES

The authors hypothesized that LV mechanical dyssynchrony assessed by LV-MD is associated with an increased risk of mortality and provides additional prognostic information on top of LV-GLS in patients with SAS.

METHODS

A total of 364 patients with SAS (aortic valve area indexed ≤0.6 cm2/m2 and/or aortic valve area ≤1 cm2), LV ejection fraction ≥50% and no or mild symptoms were enrolled. The endpoint was overall mortality.

RESULTS

During a median follow-up period of 41 months, 149 patients died. After adjustment, LV-MD ≥68 ms was significantly associated with an increased risk of mortality (adjusted HR: 1.41; 95% CI: 1.01-1.96; P = 0.044). Adding LV-MD ≥68 ms to a multivariable Cox regression model including LV-GLS ≥-15% improved predictive performance in terms of overall mortality, with improved global model fit, reclassification, and better discrimination. Patients with both criteria had an important increase in mortality compared to patients with none or one criterion (adjusted HR: 2.02; 95% CI: 1.34-3.03; P = 0.001). Interobserver reproducibility of LV-MD was good with an intraclass correlation coefficient of 0.90 (95% CI: 0.72-0.97).

CONCLUSIONS

LV-MD is a reproducible parameter independently associated with an increased risk of mortality in SAS. Increased LV-MD associated with depressed LV-GLS identifies a subgroup of patients with an increased mortality risk. Whether early aortic valve replacement improves the outcome of these patients deserves further studies.

The Presence, Location, and Degree of Late Gadolinium Enhancement in Relation to Myocardial Dysfunction and Poor Prognosis in Patients with Systemic Lupus Erythematosus

Patients with systemic lupus erythematosus (SLE) typically develop myocardial fibrosis. No studies have investigated the clinical significance of the presence, location, and degree of fibrosis in SLE patients. Seventy-four SLE patients were included. Thirty-seven non-autoimmune disease patients and thirty-seven healthy individuals were included as controls. Myocardial fibrosis was evaluated at cardiac magnetic resonance via a qualitative and quantitative assessment of late gadolinium enhancement (LGE). Myocardial function was measured via speckle-tracking echocardiography. All patients were followed up for the occurrence of major adverse cardiac events (MACE). The presence, locations, and degrees of LGE disturbed regional and global myocardial function. The presence of LGE, left ventricular free-wall LGE (LVFW LGE), and severe LGE were all independent predictors of MACE in SLE patients [LGE presence HR: 3.746 (1.434-9.79), p = 0.007; LVFW LGE HR: 2.395 (1.023-5.606), p = 0.044; severe LGE HR: 3.739 (1.241-11.266), p = 0.019]. LGE combined with SLE-related organ damage identified patients at high risk of MACE (p < 0.001). In conclusion, the presence, degree, and location of LGE were associated with myocardial dysfunction. The presence, location, and degree of LGE had the potential to independently predict poor prognosis and improve risk stratification in SLE patients.

Abnormal Mechanics Relate to Myocardial Fibrosis and Ventricular Arrhythmias in Patients With Mitral Valve Prolapse

BACKGROUND

The relation between ventricular arrhythmia and fibrosis in mitral valve prolapse (MVP) is reported, but underlying valve-induced mechanisms remain unknown. We evaluated the association between abnormal MVP-related mechanics and myocardial fibrosis, and their association with arrhythmia.

METHODS

We studied 113 patients with MVP with both echocardiogram and gadolinium cardiac magnetic resonance imaging for myocardial fibrosis. Two-dimensional and speckle-tracking echocardiography evaluated mitral regurgitation, superior leaflet and papillary muscle displacement with associated exaggerated basal myocardial systolic curling, and myocardial longitudinal strain. Follow-up assessed arrhythmic events (nonsustained or sustained ventricular tachycardia or ventricular fibrillation).

RESULTS

Myocardial fibrosis was observed in 43 patients with MVP, predominantly in the basal-midventricular inferior-lateral wall and papillary muscles. Patients with MVP with fibrosis had greater mitral regurgitation, prolapse, and superior papillary muscle displacement with basal curling and more impaired inferior-posterior basal strain than those without fibrosis (P<0.001). An abnormal strain pattern with distinct peaks pre-end-systole and post-end-systole in inferior-lateral wall was frequent in patients with fibrosis (81 versus 26%, P<0.001) but absent in patients without MVP with basal inferior-lateral wall fibrosis (n=20). During median follow-up of 1008 days, 36 of 87 patients with MVP with >6-month follow-up developed ventricular arrhythmias associated (univariable) with fibrosis, greater prolapse, mitral annular disjunction, and double-peak strain. In multivariable analysis, double-peak strain showed incremental risk of arrhythmia over fibrosis.

CONCLUSIONS

Basal inferior-posterior myocardial fibrosis in MVP is associated with abnormal MVP-related myocardial mechanics, which are potentially associated with ventricular arrhythmia. These associations suggest pathophysiological links between MVP-related mechanical abnormalities and myocardial fibrosis, which also may relate to ventricular arrhythmia and offer potential imaging markers of increased arrhythmic risk.

Myocardial Evaluation in Patients with Aortic Stenosis by Cardiac Computed Tomography

BACKGROUND

 Aortic valve stenosis (AVS) is one of the most prevalent pathologies affecting the heart that can curtail expected survival and quality of life if not managed appropriately.

CURRENT STATUS

 Cardiac computed tomography (CT) has long played a central role in this subset, mostly for severity assessment and for procedural planning. Although not as widely accepted as other imaging modalities for functional myocardial assessment [i. e., transthoracic echocardiogram (TTE), cardiac magnetic resonance (CMR)], this technique has recently increased its clinical application in this regard.

FUTURE OUTLOOK

 The ability to provide morphological, functional, tissue, and preprocedural information highlights the potential of the "all-in-one" concept of cardiac CT as a potential reality for the near future for AVS assessment. In this review article, we sought to analyze the current applications of cardiac CT that allow a full comprehensive evaluation of aortic valve disease.

KEY POINTS

  · Noninvasive myocardial tissue characterization stopped being an exclusive feature of cardiac magnetic resonance.. · Emerging acquisition methods make cardiac CT an accurate and widely accessible imaging modality.. · Cardiac CT has the potential to become a "one-stop" exam for comprehensive aortic stenosis assessment..

CITATION FORMAT

· Gama FF, Patel K, Bennett J et al. Myocardial Evaluation in Patients with Aortic Stenosis by Cardiac Computed Tomography. Fortschr Röntgenstr 2023; DOI: 10.1055/a-1999-7271.

Advanced echocardiographic assessment in adults with repaired aortic coarctation: myocardial work analysis provides novel insights on left ventricular mechanics

AIM

To analyze left ventricular (LV) mechanics through advanced echocardiography, including speckle tracking analysis and myocardial work (MW) in a cohort of adults with repaired aortic coarctation (CoA).

METHODS

Data on standard echocardiography, LV speckle-tracking and MW analysis were collected in CoA patients > 18 years with no significant recoartation or valvular disease and normal LV ejection fraction at the time of the exam. MW indices were calculated using the blood pressure measured in the right arm. A group of healthy subjects with comparable sex, age and body surface area was included for comparison.

RESULTS

Eighty-nine CoA patients and 70 healthy subjects were included. Patients had higher systolic blood pressure (p < 0.0001), LV mass index (p < 0.0001), left atrial volume index (p = 0.005) and E/E' ratio (p = 0.001). Despite similar LV ejection fraction, speckle tracking analysis revealed lower global longitudinal strain (GLS: - 18.3[17-19] vs - 20.7[19-22]%, p < 0.0001) and increased peak systolic dispersion (PSD: 45[40-54] vs 37.5[32-43] ms, p < 0.0001) in CoA patients. Global work index (GWI) and global constructive work were similar to healthy controls (p = 0.6 and 0.5, respectively), whereas CoA patients showed significant increased wasted work (GWW: 125[90-185] vs 89.5[64-127]mmHg%, p < 0.0001) and a mild but significant reduction in global work efficiency (GWE: 93%[92-95] vs 95%[94-97], p < 0.0001). Moreover, when stratifying for GLS values, MW analysis showed increased GWW and PSD with impaired GWE in 54(61%) patients with normal GLS compared to healthy individuals. Spearman's linear method illustrated an inverse relation between GWE and PSD (r: - 0.53, p < 0.0001), while GCW was associated with peak (r: 0.2, p = 0.01) and mean gradient across the descending aorta (r: 0.3, p = 0.004) and with systolic blood pressure (r: 0.48, p < 0.0001). PSD was the sole univariate predictor of GWE on linear regression analysis (β: - 0.1 [- 0.16 to - 0.07], p < 0.0001), whereas female sex, SBP and gradients across the descending aorta were independently associated with higher GCW values. When CoA patients were divided based on the history of redo CoA repair and arterial hypertension, no significant differences in MW indices were found.

CONCLUSIONS

MW is a novel echocardiographic tool, which provides additional information on LV performance in CoA patients over GLS allowing a more comprehensive understanding of LV dysfunction mechanisms in a setting of increased afterload.

The value of myocardial work in the estimation of left ventricular systolic function in patients with coronary microvascular disease: A study based on adenosine stress echocardiography

Background

Coronary microvascular dysfunction (CMD) is associated with increased cardiovascular events in patients with angina with non-obstructive coronary (ANOCA), especially heart failure. Conventional echocardiography is difficult to identify early alterations in cardiac function due to CMD.

Methods

We recruited 78 ANOCA patients. All patients underwent conventional echocardiography examination, adenosine stress echocardiography and examination of coronary flow reserve (CFR) by transthoracic echocardiography. Based on the CFR results, patients were divided into the CMD group (CFR < 2.5) and the non-CMD group (CFVR ≥ 2.5). Demographic data, conventional echocardiographic parameters, two-dimensional speckle-tracking echocardiography (2D-STE) parameters and myocardial work (MW) were compared between the two groups at rest and at stress. Logistic regression was used to analyze the factors associated with CMD.

Results

There was no significant difference in conventional echocardiography parameters, 2D-STE related indices or MW at rest between the two groups. Global work index (GWI), global contractive work (GCW), and global work efficiency (GWE) were lower in the CMD group than in the non-CMD group at stress (p = 0.040, 0.044, <0.001, respectively), but global waste work (GWW) and peak strain dispersion (PSD) were higher (both p < 0.001). GWI and GCW were associated with systolic blood pressure, diastolic blood pressure, product of heart rate and blood pressure, GLS and coronary flow velocity. While GWW was mainly correlated with PSD, GWE was correlated with PSD and GLS. In the non-CMD group, the responses to adenosine was mainly manifested as an increase in GWI, GCW and GWE (p = 0.001, 0.001, 0.009, respectively) and a decrease in PSD and GWW (p = 0.001, 0.015, respectively). In the CMD group, the response to adenosine was mainly manifested as an increase in GWW and a decrease in GWE (p = 0.002, and 0.006, respectively). In the multivariate regression analysis, we found that ΔGWW (difference in GWW before vs. after adenosine stress) and ΔPSD (difference in PSD before vs. after adenosine stress) were independent factors associated with CMD. The ROC curves showed that the composite prediction model consisting of ΔGWW and ΔPSD had excellent diagnostic value for CMD (area under the curve = 0.913).

Conclusion

In the present study, we found that CMD caused deterioration of myocardial work in ANOCA patients under adenosine stress, and that increased cardiac contraction asynchrony and wasted work may be the main changes caused by CMD.

Malignant Mitral Valve Prolapse: Risk and Prevention of Sudden Cardiac Death

Purpose of review

The purpose of this review is to explore the prevalence and risk factors for a malignant phenotype in mitral valve prolapse (MVP) characterized by life-threatening ventricular arrhythmias and sudden cardiac arrest and death (SCD), including mechanistic and pathophysiologic findings and mechanism-based potential therapies.

Recent findings

A malignant phenotype in MVP characterized by life-threatening arrhythmias has long been recognized, although MVP is often benign. Efforts to identify this malignant phenotype have revealed potential risk factors for SCD that include elongated, myxomatous leaflets, ECG changes and complex ventricular ectopy. More recently, malignant MVP has been associated with myocardial fibrosis in the papillary muscles and inferobasal left ventricular wall. This localization suggests a central role of prolapse-induced mechanical forces on the myocardium in creating an arrhythmogenic substrate and triggering life-threatening arrhythmias. This mechanism for fibrosis is also consistent with imaging evidence of prolapse-induced mechanical changes in the papillary muscles and inferobasal left ventricular wall. Currently, no therapy to prevent SCD in malignant MVP has been established and limited clinical data are available. Mechanistic information and prospective study have the potential to identify patients at risk of SCD and preventive strategies.

Summary

Malignant MVP relates to unique properties and mechanical abnormalities in the mitral valve apparatus and adjacent myocardium. Increased understanding of disease mechanisms and determinants of arrhythmias is needed to establish effective therapies.

Impact of inter-vendor variability on evaluation of left ventricular mechanical dispersion

PURPOSE

Left ventricular mechanical dispersion (LVMD) is a novel speckle tracking parameter for prognostic assessment of arrhythmic risk prediction. There is growing evidence to support its use in a variety of cardiomyopathic processes. There is paucity of data addressing any presence of inter-vendor discrepancies for LVMD. The aim of this study was to assess inter-vendor variability of LVMD in vendor specific software (VSS) and vendor independent software (VIS) in subjects with preserved and reduced left ventricular function.

METHODS

Fifty-nine subjects (14 normal subjects and 45 subjects with cardiac disease) were recruited and 2D speckle tracking echocardiographic images were acquired on two different ultrasound machines (GE and Philips). LVMD was measured by two different VSS (EchoPac GE and QLAB Philips) and one VIS (TomTec Arena).

RESULTS

There was significant bias and wide limits of agreement (LOA) in the overall cohort observed between two different VSS (17.6 ms; LOA: -29.6 to 64.8; r: .47). There was acceptable bias and narrower LOA with good agreement for LVMD between images obtained on different vendors when performed on VIS (-3.1 ms; LOA: -27.6 to 21.4; r: .75). QLAB LVMD was consistently higher than GE LVMD and TomTec LVMD in both preserved and reduced left ventricular function. LVMD measurements have high intra-vendor reproducibility with excellent inter and intra-observer agreement.

CONCLUSIONS

There was acceptable bias and narrower LOA for LVMD assessment on a VIS. Inter-vendor variability exists for LVMD assessment between VSS. Serial measurements of LVMD should be performed using a single vendor for consistent and reliable results.

Discordant severity criteria in patients with moderate aortic stenosis: prognostic implications

Background

The criteria to define the grade of aortic stenosis (AS)—aortic valve area (AVA) and mean gradient (MG) or peak jet velocity—do not always coincide into one grade. Although in severe AS, this discrepancy is well characterised, in moderate AS, the phenomenon of discordant grading has not been investigated and its prognostic implications are unknown.

Objectives

To investigate the occurrence of discordant grading in patients with moderate AS (defined by an AVA between 1.0 cm² and 1.5 cm² but with an MG <20 mm Hg) and how these patients compare with those with concordant grading moderate AS (AVA between 1.0 cm² and 1.5 cm² and MG ≥20 mm Hg) in terms of clinical outcomes.

Methods

From an ongoing registry of patients with AS, patients with moderate AS based on AVA were selected and classified into discordant or concordant grading (MG <20 mm Hg or ≥20 mm Hg, respectively). The clinical endpoint was all-cause mortality.

Results

Of 790 patients with moderate AS, 150 (19.0%) had discordant grading, moderate AS. Patients with discordant grading were older, had higher prevalence of previous myocardial infarction and left ventricular (LV) hypertrophy, larger LV end-diastolic and end-systolic volume index, higher LV filling pressure and lower LV ejection fraction and stroke volume index as compared with their counterparts. After a median follow-up of 4.9 years (IQR 3.0–8.2), patients with discordant grading had lower aortic valve replacement rates (26.7% vs 44.1%, p<0.001) and higher mortality rates (60.0% vs 43.1%, p<0.001) as compared with patients with concordant grading. Discordant grading moderate AS, combined with low LV ejection fraction, presented the higher risk of mortality (HR 2.78 (2.00–3.87), p<0.001).

Conclusion

Discordant-grading moderate AS is not uncommon and, when combined with low LV ejection fraction, is associated with high risk of mortality.

Challenges and opportunities in improving left ventricular remodelling and clinical outcome following surgical and trans-catheter aortic valve replacement

Over the last half century, surgical aortic valve replacement (SAVR) has evolved to offer a durable and efficient valve haemodynamically, with low procedural complications that allows favourable remodelling of left ventricular (LV) structure and function. The latter has become more challenging among elderly patients, particularly following trans-catheter aortic valve implantation (TAVI). Precise understanding of myocardial adaptation to pressure and volume overloading and its responses to valve surgery requires comprehensive assessments from aortic valve energy loss, valvular-vascular impedance to myocardial activation, force-velocity relationship, and myocardial strain. LV hypertrophy and myocardial fibrosis remains as the structural and morphological focus in this endeavour. Early intervention in asymptomatic aortic stenosis or regurgitation along with individualised management of hypertension and atrial fibrillation is likely to improve patient outcome. Physiological pacing via the His-Purkinje system for conduction abnormalities, further reduction in para-valvular aortic regurgitation along with therapy of angiotensin receptor blockade will improve patient outcome by facilitating hypertrophy regression, LV coordinate contraction, and global vascular function. TAVI leaflet thromboses require anticoagulation while impaired access to coronary ostia risks future TAVI-in-TAVI or coronary interventions. Until comparable long-term durability and the resolution of TAVI related complications become available, SAVR remains the first choice for lower risk younger patients.

The year in cardiology: valvular heart disease

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Peak strain dispersion within the left ventricle detected by two-dimensional speckle tracking in patients with uncomplicated systemic lupus erythematosus

Systemic lupus erythematosus (SLE) often leads to various cardiovascular diseases. We aimed to investigate the value of peak strain dispersion (PSD) in evaluating left ventricular dysfunction in patients with uncomplicated SLE. Eighty-seven female SLE patients and fifty-nine healthy female controls were recruited. The SLE patients were divided into inactive disease (SLE disease activity index (SLEDAI) ≤ 4; n = 48) and active disease (SLEDAI ≥ 5; n = 39) subgroups. Traditional echocardiography and two-dimensional speckle-tracking echocardiography were performed using a GE VividE9 ultrasound diagnostic system and an advanced quantitative analysis EchoPAC workstation (version 201), respectively. The global longitudinal strain (GLS) in the SLE with SLEDAI ≤ 4 group was comparable to that in the control group (- 19.89% vs - 20.7%; P = 0.061). However, GLS was obviously damaged in the SLE with SLEDAI ≥ 5 group compared with that in the control group (- 19.07% vs - 20.7%; P < 0.001). PSD impairment was observed in the SLE with SLEDAI ≤ 4 group (33.83 ms vs 31.44 ms; P = 0.012) and SLE with SLEDAI ≥ 5 groups (52.31 ms vs 31.44 ms; P < 0.001), but the largest difference was observed in the active disease group. Linear regression analysis showed that PSD was moderately correlated with the SLEDAI (r = 0.535; P < 0.001) in SLE patients with SLEDAI ≤ 4 and showed the best correlation with the SLEDAI (r = 0.646; P < 0.001) in the SLE patients with SLEDAI ≥ 5. A correlation between GLS and the SLEDAI (r = 0.359; P = 0.025) was found in the active disease group but not in the inactive disease group (r = 0.253; P = 0.082). PSD is more comprehensive and accurate for evaluating left ventricular subclinical dysfunction in SLE patients. In inactive SLE patients, PSD is a more sensitive index to evaluate early systolic dysfunction of the left ventricle. GLS may be a more vulnerable indicator of early left ventricular cardiac dysfunction in active SLE patients. Controlling disease activity may reduce the events of cardiac dysfunction.

Value of peak strain dispersion in discovering left ventricular dysfunction in diabetes mellitus

Cardiovascular disease is one of the main causes of death in diabetes mellitus (DM) patients. The aim of the current study was to explore the value of peak strain dispersion (PSD) for discovering early-stage left ventricular (LV) dysfunction in type 2 diabetes mellitus (T2DM) patients. One hundred and one T2DM patients and sixty healthy subjects were selected for this study. T2DM patients were further divided into controlled blood glucose (HbA1c < 7%, n = 46) and uncontrolled blood glucose (HbA1c ≥ 7%, n = 55) subgroups. All participants underwent conventional echocardiography and two-dimensional speckle-tracking echocardiography. Our results showed that an obvious difference was not observed in global longitudinal strain (GLS) between the controlled blood glucose group and the control group (− 20.34% vs − 21.22%, P = 0.068). Compared with the healthy controls, the uncontrolled blood glucose group showed an impaired GLS (− 18.62% vs − 21.22%, P < 0.001). Nevertheless, PSD was appreciably increased in the controlled blood glucose group (36.02 ms vs 32.48 ms, P = 0.01) and uncontrolled blood glucose group (57.51 ms vs 32.48 ms, P < 0.001). Multivariate linear regression analysis showed that HbA1c was closely related to PSD lesion in the LV in the T2DM group (β = 0.520, P < 0.001). PSD plays an important role in evaluating the coordination and synchronization of myocardial movement and provides a more accurate and sensitive index assessment of early LV systolic function in T2DM patients. In addition, HbA1c levels were related to LV dysfunction.

Combined right and left ventricular mechanical dispersion enhance the arrhythmic risk stratification in hypertrophic cardiomyopathy

BACKGROUND

Ventricular arrhythmias are the most frequent cause of sudden cardiac death in individuals with hypertrophic cardiomyopathy (HCM). In the present study we investigated if combined left ventricular (LV) and right ventricular (RV) mechanical dispersion (MD) are correlated with ventricular arrhythmias. We aimed also to analyze if MD enhances the arrhythmic risk stratification in HCM.

METHODS

The cohort included 47 subjects with HCM and 36 healthy individuals. All the studied population underwent clinical, 24-h electrocardiographic (ECG) monitoring for detection and description of non-sustained ventricular tachycardia (NSVT) in terms of number of events, maximal rate and length and comprehensive transthoracic echocardiography, including strain rate imaging. MD was calculated as standard deviation of time from the peak of R wave on ECG to maximum LV or RV shortening in 17 LV and 3 RV segments.

RESULTS

HCM subjects with NSVT on ECG monitoring had increased LVMD (81±18ms vs 42±8ms) and RVMD (52±26 vs 25±23ms) compared with the HCM group without NSVT or compared with the healthy controls. On receiver operating characteristic curves the cut-off values associated with optimal specificity and sensitivity were 62ms for LVMD and 39ms for RVMD. LVMD (OR=1.86, 95% CI 1-1.06, p=0.01) and RVMD (OR=1.04, 95% CI 1.01-1.07, p=0.003) were the only independent variables that correlated with longer and faster NSVT and furthermore improved the risk stratification of NSVTs.

CONCLUSIONS

In a cohort of subjects with HCM, LVMD and RVMD correlates with the presence of NSVT on ECG monitoring. Combined LVMD and RVMD may improve the risk stratification of HCM with NSVT.

Impact of transcatheter aortic valve implantation on mechanical dispersion

Objectives

The physiological determinants of left ventricular (LV) mechanical dispersion (MD) are not fully explored. We aimed to investigate the impact of afterload reduction and changes in ventricular conduction on LV MD after transcatheter aortic valve implantation (TAVI).

Methods

Patients with severe aortic stenosis (AS) were examined in a prospective, repeated measures observational cohort study before and after an uncomplicated transfemoral TAVI in a single tertiary centre. LV MD was assessed by speckle tracking echocardiography. Valvulo-arterial impedance (ZVA) was used as a measure of global afterload.

Results

We included 140 consecutive patients (83±8 years old, 49% women, logistic EuroSCORE 16±10) with severe AS (valve area 0.7±0.2 cm², mean transvalvular gradient 54±18 mm Hg) and a relatively preserved LV ejection fraction (52%±11%). After TAVI, we observed favourable changes in transvalvular gradients and ZVA in all patients. Compared with baseline, postprocedural MD was significantly lower in 108 patients with unchanged ventricular conduction (55±17 ms vs 51±17 ms, p=0.02) and higher in 28 patients with TAVI-induced left bundle branch block (51±13 ms vs 62±19 ms, p≤0.001). During 22±9 months observation, 22 patients died. Postprocedural MD was associated with mortality in a univariate Cox regression model (HR=1.24 (1.01-1.52), p<0.04, per 10 ms increase).

Conclusions

Isolated afterload reduction was associated with reduction of MD, while concomitant impairment of ventricular conduction resulted in a more pronounced MD after TAVI, indicating that loading conditions and conduction should be considered when evaluating MD. A pronounced postprocedural LV MD was associated with mortality.

Left ventricular mechanical dispersion in flow-gradient patterns of severe aortic stenosis with narrow QRS complex

Patients with severe aortic stenosis are classified according to flow-gradient patterns. We investigated whether left ventricular (LV) mechanical dispersion, a marker of dyssynchrony and predictor of mortality, is associated with low-flow status in aortic stenosis. 316 consecutive patients with aortic stenosis and QRS duration < 120 ms were included in the retrospective analysis. Patients with severe aortic stenosis (aortic valve area ≤ 1.0 cm²) were classified as normal-flow (NF; stroke volume index > 35 ml/m²) high-gradient (HG; mean transvalvular gradient ≥ 40 mmHg) (n = 79), NF low-gradient (LG) (n = 62), low-flow (LF) LG ejection fraction (EF) ≥ 50% (n = 57), and LF LG EF < 50% (n = 23). Patients with moderate aortic stenosis (aortic valve area 1.5–1.0 cm²; n = 95) served as comparison group. Mechanical dispersion (calculated as standard deviation of time from Q/S onset on electrocardiogram to peak longitudinal strain in 17 left ventricular segments) was similar in patients with NF HG (49.4 ± 14.7 ms), NF LG (43.5 ± 12.9 ms), LF LG EF ≥ 50% (47.2 ± 16.3 ms) and moderate aortic stenosis (44.2 ± 15.7 ms). In patients with LF LG EF < 50%, mechanical dispersion was increased (60.8 ± 20.7 ms, p < 0.05 vs. NF HG, NF LG, LF LG EF ≥ 50% and moderate AS). Mechanical dispersion correlated with global longitudinal strain (r = 0.1354, p = 0.0160) and heart rate (r = 0.1587, p = 0.0047), but not with parameters of aortic stenosis. Mechanical dispersion was similar among flow-gradient subgroups of severe aortic stenosis with preserved LVEF, but increased in patients with low-flow low-gradient and reduced LVEF. These findings indicate that mechanical dispersion is rather a marker of systolic myocardial dysfunction than of aortic stenosis.