Myocardial deformation and rotational profiles in mitral valve prolapse

Echocardiographic assessment of left ventricular mechanics in individuals with mitral valve prolapse: a systematic review and meta-analysis

PURPOSE

During the last decade, a number of echocardiographic studies have employed speckle tracking echocardiography (STE) for assessing myocardial deformation properties in individuals with mitral valve prolapse (MVP), reporting not univocal results. Accordingly, we performed a systematic review and meta-analysis to summarize the main findings of these studies and to examine the overall influence of MVP on left ventricular (LV) global longitudinal strain (GLS).

METHODS

All echocardiographic studies assessing conventional echoDoppler parameters and myocardial strain indices in MVP individuals vs. controls without MVP, selected from PubMed and EMBASE databases, were included. The risk of bias was assessed by using the National Institutes of Health (NIH) Quality Assessment of Case-Control Studies. Continuous data (LV-GLS) were pooled as a standardized mean difference (SMD) comparing MVP group with healthy controls. The overall SMD of LV-GLS was calculated using the random-effect model.

RESULTS

The full-texts of 15 studies with 1088 individuals with MVP and 591 healthy controls were analyzed. Average LV-GLS magnitude was significantly, even though modestly, reduced in MVP individuals in comparison to controls (19.4 ± 3.4% vs. 21.1 ± 2.8%, P < 0.001). The overall effect of MVP on LV-GLS was small-to-medium (SMD - 0.54, 95%CI -0.76,-0.32, P < 0.001). Substantial heterogeneity was detected for the included studies, with an overall I2 statistic value of 75.9% (P < 0.001). Egger's test for a regression intercept gave a P-value of 0.58, indicating no publication bias. On meta-regression analysis, none of the moderators (the age, the percentage of females among MVP individuals, body mass index, heart rate and systolic blood pressure of MVP individuals, the degree of mitral regurgitation, the type of ultrasound machine employed for strain echocardiographic imaging and finally the beta blocker treatment) was significantly associated with effect modification (all P < 0.05). Regional strain analysis, performed by two-third of the studies, highlighted a more enhanced reduction in myocardial strain parameters at level of the LV basal infero-lateral segments in all directions (longitudinal, circumferential and radial), with apical sparing.

CONCLUSIONS

The longitudinal strain impairment detected in MVP individuals is more regional than global, with peculiar involvement of the LV basal infero-lateral segments and relative apical sparing pattern.

Cardiac magnetic resonance imaging in the evaluation and management of mitral valve prolapse - a comprehensive review

Mitral valve prolapse is a common valve disorder that usually has a benign prognosis unless there is significant regurgitation or LV impairment. However, a subset of patients are at an increased risk of ventricular arrhythmias and sudden cardiac death, which has led to the recognition of "arrhythmic mitral valve prolapse" as a clinical entity. Emerging risk factors include mitral annular disjunction and myocardial fibrosis. While echocardiography remains the primary method of evaluation, cardiac magnetic resonance has become crucial in managing this condition. Cine magnetic resonance sequences provide accurate characterization of prolapse and annular disjunction, assessment of ventricular volumes and function, identification of early dysfunction and remodeling, and quantitative assessment of mitral regurgitation when integrated with flow imaging. However, the unique strength of magnetic resonance lies in its ability to identify tissue changes. T1 mapping sequences identify diffuse fibrosis, in turn related to early ventricular dysfunction and remodeling. Late gadolinium enhancement sequences detect replacement fibrosis, an independent risk factor for ventricular arrhythmias and sudden cardiac death. There are consensus documents and reviews on the use of cardiac magnetic resonance specifically in arrhythmic mitral valve prolapse. However, in this article, we propose an algorithm for the broader use of cardiac magnetic resonance in managing this condition in various scenarios. Future advancements may involve implementing techniques for tissue characterization and flow analysis, such as 4D flow imaging, to identify patients with ventricular dysfunction and remodeling, increased arrhythmic risk, and more accurate grading of mitral regurgitation, ultimately benefiting patient selection for surgical therapy.

Cardiac Imaging for the Assessment of Left Atrial Mechanics Across Heart Failure Stages

The left atrium (LA) is emerging as a key element in the pathophysiology of several cardiac diseases due to having an active role in contrasting heart failure (HF) progression. Its morphological and functional remodeling occurs progressively according to pressure or volume overload generated by the underlying disease, and its ability of adaptation contributes to avoid pulmonary circulation congestion and to postpone HF symptoms. Moreover, early signs of LA dysfunction can anticipate and predict the clinical course of HF diseases before the symptom onset which, particularly, also applies to patients with increased risk of HF with still normal cardiac structure (stage A HF). The study of LA mechanics (chamber morphology and function) is moving from a research interest to a clinical application thanks to a great clinical, prognostic, and pathophysiological significance. This process is promoted by the technological progress of cardiac imaging which increases the availability of easy-to-use tools for clinicians and HF specialists. Two-dimensional (2D) speckle tracking echocardiography and feature tracking cardiac magnetic resonance are becoming essential for daily practice. In this context, a deep understanding of LA mechanics, its prognostic significance, and the available approaches are essential to improve clinical practice. The present review will focus on LA mechanics, discussing atrial physiology and pathophysiology of main cardiac diseases across the HF stages with specific attention to the prognostic significance. Imaging techniques for LA mechanics assessment will be discussed with an overlook on the dynamic (under stress) evaluation of the chamber.

Loss of left ventricular rotation is a significant determinant of functional mitral regurgitation

AIM

To evaluate insufficient rotational movement of the left ventricle (LV) as a potential novel mechanism for functional regurgitation of the mitral valve (FMR).

METHODS AND RESULTS

We compared reference subjects and patients with LV dysfunction (LVD, ejection fraction EF < 50%) with and without FMR (regurgitant volume RVol>10 ml). Subjects without structural mitral valve pathology undergoing cardiac MRI were evaluated. Delayed enhancement, global LV remodeling parameters, systolic twist and torsion were measured (using manual and novel automated cardiac MRI tissue-tracking). The study included 117 subjects with mean ± SD age 50.4 ± 17.8 years, of which 30.8% were female. Compared to subjects with LVD without FMR (n = 31), those with FMR (n = 37) had similar clinical characteristics, diagnoses, delayed enhancement, EF, and longitudinal strain. Subjects with FMR had significantly larger left ventricles (EDVi:136.6 ± 41.8 vs 97.5 ± 26.2 ml/m, p < 0.0001) with wider separation between papillary muscles (21.1 ± 7.6 vs 17.2 ± 5.7 mm, p = 0.023). Notably, they had lower apical (p < 0.0001) but not basal rotation and lower peak systolic twist (3.1 ± 2.4° vs 5.5 ± 2.5°, p < 0.0001) and torsion (0.56 ± 0.38°/cm vs 0.88 ± 0.52°/cm, p = 0.004). In a multivariate model for RVol including age, gender, twist, LV end-diastolic volume, sphericity index and separation between papillary muscles, only gender, volume and twist were significant. Twist was the most powerful correlate (beta -2.23, CI -3.26 to -1.23 p < 0.001). In patients with FMR, peak systolic twist negatively correlates with RVol (r = -0.73, p < 0.0001).

CONCLUSION

Reduced rotational systolic LV motion is significantly and independently associated with RVol among patients with FMR, suggesting a novel pathophysiological mechanism and a potential therapeutic target.

Contractile Differences Detected by Speckle Tracking Echocardiography in Pediatric Patients with Mitral Valve Prolapse

Mitral valve prolapse (MVP) is the most common valvar dysfunction in children. There is emerging evidence that MVP is not always a benign entity, hence identification of underlying mechanisms is pertinent to clinical management. Our group previously identified a ventricular contraction abnormality named end-systolic basal eversion (ESBE) in adults that contributed to MVP. The aim of this study was to evaluate regional circumferential strain in pediatric patients with MVP and ESBE compared to normal controls. Left ventricular circumferential strain was assessed in 16 pediatric patients referred for clinical echocardiographic examination with MVP and ESBE (MVP group) and compared to age-gender-matched healthy subjects. ESBE has been previously described as late systolic bileaflet mitral valve prolapse, papillary traction, and concomitant late systolic outward movement of the basal inferior myocardium. The mean age of the MVP group was 13.8 ± 4.6 year and 75% were female. All patients with MVP and controls had qualitatively normal systolic cardiac function. The MVP group had significantly lower regional strain values for 11/16 of the segments including all 6 basal segments. Importantly, the basal inferior (- 17.02 ± 8.32% vs. - 26.10 ± 3.18, p = 0.001) and basal inferolateral (- 19.53 ± 9.76 vs. - 26.10 ± 3.18, p = 0.03) had the lowest strain values compared to the average of all other segments suggesting weaker contraction in the basal inferior segments. Pediatric patients with MVP and ESBE are subject to a similar left ventricular mechanical dysfunction previously described in adults. ESBE was evident by decreased basal circumferential strain values. These findings denoted weaker contraction which is believed to propagate the late systolic outward movement of the basal ventricular myocardium.

Mitral valve prolapse morphofunctional features by cardiovascular magnetic resonance: more than just a valvular disease

INTRODUCTION

Mitral valve (MV) prolapse (MVP) is a primary valvular abnormality. We hypothesized that additionally there are concomitant abnormalities of the left ventricle (LV) and MV apparatus in this entity even in the absence of significant mitral regurgitation (MR).

OBJECTIVE

To characterize MV and LV anatomic and functional features in MVP with preserved LV ejection fraction, with and without significant MR, using cardiovascular magnetic resonance (CMR).

METHODS

Consecutive MVP patients (n = 80, mean 52 years, 37% males) with preserved LV ejection fraction, and 44 controls (46 years, 52% males) by CMR were included, as well as 13 additional patients with "borderline" MVP. From cine images we quantified LV volumes, MV and LV anatomic measurements (including angle between diastolic and systolic annular planes, annular displacement, and basal inferolateral hypertrophy) and, using feature tracking, longitudinal and circumferential peak systolic strains.

RESULTS

Significant MR was found in 46 (56%) MVP patients. Compared with controls, MVP patients had LV enlargement, basal inferolateral hypertrophy, higher posterior annular excursion, and reduced shortening of the papillary muscles. LV basal strains were significantly increased, particularly in several basal segments. These differences remained significant in patients without significant MR, and many persisted in "borderline" MVP.

CONCLUSIONS

In patients with MVP and preserved LV ejection fraction there is LV dilatation, basal inferolateral hypertrophy, exaggerated posterior annular displacement and increased basal deformation, even in the absence of significant MR or overt MVP. These findings suggest that MVP is a disease not only of the MV but also of the adjacent myocardium.

Changes in Left Ventricular Ejection Fraction after Mitral Valve Repair for Primary Mitral Regurgitation

This study sought to identify the short- and long-term changes in left ventricular ejection fraction (LVEF) after mitral valve repair (MVr) in patients with chronic primary mitral regurgitation according to preoperative LVEF (pre-LVEF) and preoperative left ventricular end-systolic diameter (pre-LVESD). This study evaluated 461 patients. Restricted cubic spline regression models were constructed to demonstrate the long-term changes in postoperative LVEF (post-LVEF). The patients were divided into four groups according to pre-LVEF (<50%, 50–60%, 60–70%, and ≥70%). The higher the pre-LVEF was, the greater was the decrease in LVEF immediately after MVr. In the same pre-LVEF range, immediate post-LVEF was lower in patients with pre-LVESD ≥ 40 mm than in those with pre-LVESD < 40 mm. The patterns of long-term changes in post-LVEF differed according to pre-LVEF (p for interaction < 0.001). The long-term post-LVEF reached a plateau of approximately 60% when the pre-LVEF was ≥50%, but it seemed to show a downward trend after reaching a peak at approximately 3–4 years after MVr when the pre-LVEF was ≥70%. The patterns of short- and long-term changes in post-LVEF differed according to pre-LVEF and pre-LVESD values in patients with chronic primary mitral regurgitation after MVr.

Asymptomatic Left Ventricular Dysfunction: Is There a Role for Screening in General Population?

Stage A and B heart failure (HF) include asymptomatic patients without and with structural cardiac disorder, respectively. Asymptomatic left ventricular (LV) dysfunction represents an early stage of HF that should be recognized to prevent overt HF development. Echocardiography plays a pivotal role in assessment of cardiac structure and function and represents the ideal imaging technique for screening in the general population, thanks to its availability, feasibility, and low cost. Traditional echocardiography, with LV systolic and diastolic function and cardiac remodeling assessment, is usually performed. Development of new technologies may offer additional information and insights in detection of early LV dysfunction.

Mitigating cardiac dysfunction by TOE-guided cardioplegia and mitral valve repair

Based on current guidelines, 15% to 20% of patients undergoing mitral valve repair for regurgitation develop left ventricular dysfunction (ejection fraction < 50%-55%) despite a normal baseline. Two schools of thought have been debated: preexisting myocardial disease or suboptimal intraoperative myocardial protection. In our view, they could be reconciled. It is well recognized that left ventricular ejection fraction with a standard cut off at 50%-55% has limited sensitivity in detecting early systolic impairment in mitral regurgitation patients. Mitral regurgitation also leads to mitochondrial oxidative stress, thus rendering the myocardium more susceptible to ischemia-reperfusion injury and precipitating postoperative cardiac dysfunction. The fall in left ventricular ejection fraction early after mitral valve repair was shown to be caused by the reduction in both myocardial contractility and left ventricular stroke volume. To mitigate the risk to myocardial reperfusion injury, appropriate cardioplegia volume and distribution and well-defined surgical repair processes are equally important. We use transesophageal echocardiography-guided cardioplegia delivery, imaging the intramyocardial flow and ensuring adequate protection of the subendocardium during mitral valve repair. Mild aortic regurgitation on a beating heart often leads to left ventricular dilatation with diminished cardioplegia flow in the myocardium, thus requiring direct ostia cardioplegia. Systematic transesophageal echocardiography assessment before surgery is essential for establishing the mitral regurgitation mechanisms and translating them into precise surgical repair strategies. The benefits of transesophageal echocardiography-guided cardioplegia delivery warrant further clinical trials in order to evolve into part of a high surgical standard.

Early Impairment Left Ventricular Mechanics in Children With Mitral Valve Prolapse

Early impairment of left ventricular (LV) function has been reported in some inherited connective tissue diseases such as Marfan syndrome or rheumatic heart disease in pediatric patients. However, there is no study about cardiac strain in pediatric patients with primary mitral valve prolapse (MVP). The aim of this study was to evaluate the LV functions in pediatric patients with primary MVP, mild or moderate mitral regurgitation (MR), and normal LV ejection fraction. The study group included 72 consecutive patients (40 female, mean age: 13.1 ± 5.2 with primary MVP who had mild or moderate MR, and normal systolic function (LV ejection fraction ≥60%) were compared with 40 healthy children using conventional echocardiography, tissue Doppler imaging, and 2-dimensional speckle tracking echocardiography. Patients were divided into subgroups according to the MR severity: mild (n:34), and moderate (n:38) and leaflet thickness: classical (n: 40), and nonclassical (n: 32). The children with MR had significantly lower values for global early diastolic strain rate ([SRe] patients: 1.40 ± 0.25 vs controls: 1.62 ± 0.54; p = 0.001), and E/SRe (patients: 72.7 ± 5.6 vs controls: 62.1 ± 4.9; p <0.04) when compared with the control group. In subgroup analysis, SRe (mild: 1.49 ± 0.38 vs moderate: 1.32 ± 0.31; p <0.001) was lower in MVP patients with moderate MR compared to mild MR, and E/SRe (mild: 69.4 ± 5.1 vs moderate: 75.1 ± 6.4; p <0.001) value was higher in MVP patients with moderate MR compared to mild MR. Diatolic strain parameters, SRe, and E/SRe are more sensitive markers of early subtle myocardial injury in pediatric patients with primary MVP.

Ten Years of 2D Longitudinal Strain for Early Myocardial Dysfunction Detection: A Clinical Overview

In recent years, the role of left ventricular ejection fraction (EF) as the gold standard parameter for the evaluation of systolic function has been questioned, and many efforts have been concentrated in the clinical validation of new noninvasive tools for the study of myocardial contractility. Improvement in the accuracy of speckle-tracking echocardiography has resulted in a large amount of research showing the ability of two-dimensional strain to overcome EF limitations in the majority of primary and secondary heart diseases. Currently, global longitudinal strain (GLS) is considered the most accurate and sensitive parameter for the assessment of early left ventricular dysfunction. This review summarizes the advantages that this measurement can provide in several clinical settings. Moreover, the important cautions that should be considered in making the choice to use GLS also are addressed. Finally, a special focus on bull's-eye polar maps for the assessment of regional changes of longitudinal function and the usefulness of these maps in the differential diagnosis of several diseases is provided.

Interactions between mitral valve and left ventricle analysed by 2D speckle tracking in patients with mitral valve prolapse: one more piece to the puzzle

Aims

Two-dimensional echocardiography often reveals abnormal left ventricle (LV) lateral wall kinetics in patients presenting with mitral valve prolapse (MVP). However, relations between MVP and LV deformation are not clearly established. The aim of this study was to assess and quantify mitral valve chordae, leaflets, and LV myocardial interactions using speckle tracking echocardiography (STE).

Methods and results

Using STE-derived longitudinal strain curves, LV peak longitudinal strain (PLS, %), post-systolic index (PSI), and pre-stretch index (PST) were analysed in 100 patients with MVP and normal LV ejection fraction. Global, regional, and segmental values were compared according to mitral regurgitation severity and MVP location. Twenty healthy subjects served as control patients. There was no significant difference among control and MVP group for global and regional PLS (-23.7 ± 3.2 vs. -23.1 ± 2.2). In contrast, patients with MVP had significantly higher values of global PST (3.2 ± 4.1 vs. 1.3 ± 1.2; P = 0.01) and global PSI (3.2 ± 0.4 vs. 1.7 ± 1.1; P = 0.05) compared with controls, located mainly in the lateral wall and basal segments. Both anterior and posterior MVPs were responsible for PSI in basal inferior segments and PST in anterior ones. Mid-wall segmental deformation pattern changes were mainly observed at the level of the segments adjacent to the papillary muscle.

Conclusion

This study supports the hypothesis that pathological early-systolic shortening and late systolic, post-systolic deformation are attributed to an increased interaction between wall deformation and mitral valve events in patients with MVP. STE is a useful tool in the assessment of interplays between MV leaflets and myocardium and helps to demonstrate changes in temporal pattern of myocardial deformation.

Mitral Prolapse: An Old Mysterious Entity - The Incremental Role of Multimodality Imaging in Sports Eligibility

Mitral valve prolapse is generally a benign condition characterized by fibromyxomatous changes of the mitral leaflet with displacement into the left atrium and late-systolic regurgitation. Although it is an old clinical entity, it still arouses perplexity in diagnosis and clinical management. Complications, such as mitral regurgitation (MR), atrial fibrillation, congestive heart failure, endocarditis, ventricular arrhythmias, and sudden cardiac death (SCD), have been reported. A large proportion of the overall causes of SCD in young competitive athletes is explained by mitral valve prolapse. Recent studies have shown the fibrosis of the papillary muscles and inferobasal left ventricular wall in mitral valve prolapse, suggesting a possible origin of ventricular fatal arrhythmias. Athletes with mitral valve prolapse and MR should undergo annual evaluations including physical examination, echocardiogram, and exercise stress testing to evaluate the cardiovascular risks of competitive sports and obtain the eligibility. In this setting, multimodality imaging techniques – echocardiography, cardiac magnetic resonance, and cardiac computed tomography – should provide a broad spectrum of information, from diagnosis to clinical management of the major clinical profiles of the disease.

Contemporary Imaging in Takotsubo Syndrome

Transthoracic echocardiography is the first-line imaging modality for evaluating patients with Takotsubo syndrome (TTS). Beyond diagnosis, TTE enables detection of peculiar complications and is useful for risk stratification and management of patients with cardiogenic shock. Cardiac magnetic resonance can be used to detect myocardial edema typically associated with TTS and is helpful in the differential diagnosis with other disease states. Coronary computed tomography angiography can be performed as an alternative to coronary angiography to confirm coronary artery patency. Molecular imaging is a promising approach for identifying patients at increased risk of recurrence.

Effect of Fluoxetine Administration on Clinical and Echocardiographic Findings in Patients with Mitral Valve Prolapse and Generalized Anxiety Disorder: Randomized Clinical Trial

Background

Mitral valve prolapse (MVP) is accompanied by mental disorders including anxiety, which has similar presentations as MVP. It is hypothesised that treatment of anxiety might reduce the symptoms of MVP.

Objective

The aim of this study was to assess the clinical and echocardiographic effects of fluoxetine administration in patients with MVP and anxiety.

Methods

This randomized clinical trial was conducted on patients with documented MVP and generalised anxiety disorder (GAD) who were referred to Mashhad University of Medical Sciences cardiology clinics, Mashhad, Iran in 2015. Subjects were randomly assigned to intervention group who received propranolol and fluoxetine (both at 10 mg/day) and control group who received 10 mg/day propranolol. Assessments included echocardiography and GAD-7 questionnaire and rating of chest pain, that were performed at baseline and then weekly for 4 weeks. Analysis was performed using the Mann-Whitney U test and Two-way Repeated Measures Analysis of Variance (ANOVA).

Results

Sixty patients (25 male/ 35 female) with a mean age of 22.9 ± 2.5 years were studied in two groups of intervention (n = 30) and control (n = 30). GAD score was significantly higher in the intervention group (17.37 ± 1.61) compared with the control group (14.17 ± 0.83) (p<0.001). No significant difference was observed for changes in left atrium diameter, mitral annular diameter, left ventricular diameter or ejection fraction (p>0.05). Pain severity was reduced significantly more in control group (3.27 ± 1.26) compared to intervention group (2.80 ± 0.85) after treatment (p<0.001).

Conclusions

This study revealed that the co-administration of fluoxetine and propranolol may not only have no effective in improving echocardiographic changes of MVP but may also aggravate subjective findings of patients with MVP and GAD.

Trial registration

The trial is registered at the Iranian Clinical Trial Registry (IRCT.ir) with the IRCT identification number IRCT2014102819721N1.

Funding

This research has been financially supported by Research Council of Sabzevar University of Medical Sciences.

Tissue Tracking Technology for Assessing Cardiac Mechanics: Principles, Normal Values, and Clinical Applications

Tissue tracking technologies such as speckle tracking echocardiography and feature tracking cardiac magnetic resonance have enhanced the noninvasive assessment of myocardial deformation in clinical research and clinical practice. The widespread enthusiasm for using tissue tracking techniques in research and clinical practice stems from the ready applicability of these technologies to routine echocardiographic or cardiac magnetic resonance images. The technology is common to both modalities, and derived parameters to describe myocardial mechanics are the similar, albeit with different accuracies. We provide an overview of the normal values and reproducibility of the clinically applicable parameters, together with their clinical validation. The use of these technologies in different clinical scenarios, and the additive value to current imaging diagnostics are discussed.

Usefulness of Left Atrial Reservoir Size and Left Ventricular Untwisting Rate for Predicting Outcome in Primary Mitral Regurgitation

The present study proposed to evaluate whether analysis of cardiac mechanics through speckle-tracking imaging is useful for risk stratification in asymptomatic patients with chronic primary mitral regurgitation (MR). We prospectively enrolled 67 patients (mean age 57 ± 18 years) and followed them over time. MR was mild in 20 patients (30%), moderate in 24 (36%), and severe in 23 (34%). After a mean time of 24.8 ± 17 months, 34 patients (51%) remained asymptomatic, whereas 33 (49%) developed events (19 underwent mitral valve surgery, 9 required hospitalization for acute heart failure, and 5 patients died). Compared to asymptomatic patients, those with events at baseline showed more severe MR, larger and spherical ventricles, diastolic dysfunction, and greater systolic pulmonary arterial pressure. Moreover, patients with events had decreased left atrial (LA) reservoir (p <0.001) and left ventricular (LV) untwisting rate (p <0.001). On univariate Cox regression analysis, effective regurgitant orifice area (p <0.001), vena contracta (p <0.001), systolic pulmonary arterial pressure (p = 0.003), LV end-systolic diameter (p <0.001), E/E' ratio (p = 0.004), LA volume (p = 0.001), LA reservoir (p <0.001), and LV untwisting rate (p <0.001) were associated with an increased risk of events. On multivariate analysis, only LA reservoir (p = 0.013) and LV untwisting rate were independent predictors (p = 0.017) of outcome. Moreover, LA reservoir evaluation significantly improved (p = 0.013) risk stratification compared to recommended parameters. In conclusion, impaired cardiac mechanics is more closely associated than severity of MR with the occurrence of events in asymptomatic chronic primary MR.

Strain Echocardiography and Myocardial Mechanics: From Basics to Clinical Applications

The aim of this review is to summarize the recent developments in strain imaging, an evolving technique – from tissue Doppler to 3D echocardiography – for resolving the complex left ventricular mechanics. Following a brief overview of the different used technique to extract myocardial deformation data, the authors summarize the role of the technique in the assessment of cardiac mechanics and its role in the clinical arena.

Early left ventricular regional contractile impairment in chronic mitral regurgitation occurs in a consistent, heterogeneous pattern

OBJECTIVES

The clinical guidelines for asymptomatic patients with chronic mitral regurgitation (MR) use the ejection fraction (EF) to trigger surgical referral. We hypothesized that the EF is not sensitive enough to detect the earliest contractile injury in chronic MR and that the injury associated with chronic MR is not global but heterogeneous, occurring regionally and predictably, before the onset of global left ventricular (LV) dysfunction.

METHODS

Fifteen patients with chronic MR and normal LVEF by echocardiography underwent cardiac magnetic resonance imaging with tissue tagging. Point-specific comparisons (at 15,300 LV grid points) of multiple strain parameters to a normal human strain database allowed normalization of patient-specific regional contractile function. Data were mapped over patient-specific 3-dimensional geometry and averaged across 6 LV regions.

RESULTS

Global LV longitudinal and circumferential myocardial strains were normal for all 15 patients with MR compared with normal controls (P>.05). Despite preserved global function, the anteroseptum and posteroseptum demonstrated significantly worse contractile function compared with other LV regions (P=.003 and P=.035, respectively). Hypercontractile regions (lateral walls) appeared to compensate (P=.002) for the reduced septal contractile function, masking injury detection by global indexes.

CONCLUSIONS

The earliest contractile injury seen in patients with MR is heterogeneous and consistently distributed along the LV septum. Compensatory responses include hypercontractility of other regions. These data suggest that rather than relying on global LV contractile metrics, which cannot detect early injury, patients might be better served by undergoing directed surveillance of "sentinel" LV regions (LV septum) with high-resolution metrics of regional contractile function.