Two-dimensional strain analysis in patients with hypertrophic cardiomyopathy and normal systolic function: a 12-month follow-up study

Global Longitudinal Strain May Be the One that Appropriately Identifies Candidates of ICD Implantation

Hypertrophic cardiomyopathy (HCM) significantly contributes to an elevated risk of sudden cardiac death. Primary prevention is implemented by using an implantable cardioverter defibrillator (ICD). However, all of the HCM patients do not really need ICD therapy. Providing a superior index for ICD indication compared with the current indices like ejection fraction is essential to differentiate high-risk patients efficiently. The present study assessed the potential of global longitudinal strain (GLS) for the differentiation of HCM patients based on their need for ICD shocks. Patients with HCM were considered in four defined centers between March and June 2021. Those with previous ICD implantation or current candidates for ICD therapy were included in the study. Participants were subjected to speckle-tracking echocardiography, and GLS as well as some other echocardiographic parameters were recorded. Afterwards, data from implanted ICDs were extracted. Patients who received ICD shocks (appropriate) due to ventricular tachycardia (VT)/ventricular fibrillation (VF) were categorized in group A. The remaining patients were constituted group B who received inappropriate shocks, i.e., other than VT/VF. Overall, 34 patients were found eligible to participate with a mean age of 62 ± 16.1 years including 64.7% of males. Among a variety of echocardiographic parameters, GLS was the sole one that was significantly higher in group A compared with that in group B. Our findings revealed that only GLS could predict fatal arrhythmias. To substantiate, the odds of VT were raised by 43% with a single increase in GLS unit. GLS showed the highest accuracy for ICD indication among HCM patients and, therefore, could be a solid and early criterion to predict the incidence of life-threatening arrhythmias. In this regard, identifying appropriate HCM patients with respect to their need for ICD therapy is feasible.

The impact of image and performance enhancing drugs on atrial structure and function in resistance trained individuals

BACKGROUND

Image and performance enhancing drugs (IPEDs) are commonly used in resistance trained (RT) individuals and negatively impact left ventricular (LV) structure and function. Few studies have investigated the impact of IPEDs on atrial structure and function with no previous studies investigating bi-atrial strain. Additionally, the impact of current use vs. past use of IPEDs is unclear.

METHODS

Utilising a cross-sectional design, male (n = 81) and female (n = 15) RT individuals were grouped based on IPED user status: current (n = 57), past (n = 19) and non-users (n = 20). Participants completed IPED questionnaires, anthropometrical measurements, electrocardiography, and transthoracic echocardiography with strain imaging. Structural cardiac data was allometrically scaled to body surface area (BSA) according to laws of geometric similarity.

RESULTS

Body mass and BSA were greater in current users than past and non-users of IPEDs (p < 0.01). Absolute left atrial (LA) volume (60 ± 17 vs 46 ± 12, p = 0.001) and right atrial (RA) area (19 ± 4 vs 15 ± 3, p < 0.001) were greater in current users than non-users but this difference was lost following scaling (p > 0.05). Left atrial reservoir (p = 0.008, p < 0.001) and conduit (p < 0.001, p < 0.001) strain were lower in current users than past and non-users (conduit: current = 22 ± 6, past = 29 ± 9 and non-users = 31 ± 7 and reservoir: current = 33 ± 8, past = 39 ± 8, non-users = 42 ± 8). Right atrial reservoir (p = 0.015) and conduit (p = 0.007) strain were lower in current than non-users (conduit: current = 25 ± 8, non-users = 33 ± 10 and reservoir: current = 36 ± 10, non-users = 44 ± 13). Current users showed reduced LV diastolic function (A wave: p = 0.022, p = 0.049 and E/A ratio: p = 0.039, p < 0.001) and higher LA stiffness (p = 0.001, p < 0.001) than past and non-users (A wave: current = 0.54 ± 0.1, past = 0.46 ± 0.1, non-users = 0.47 ± 0.09 and E/A ratio: current = 1.5 ± 0.5, past = 1.8 ± 0.4, non-users = 1.9 ± 0.4, LA stiffness: current = 0.21 ± 0.7, past = 0.15 ± 0.04, non-users = 0.15 ± 0.07).

CONCLUSION

Resistance trained individuals using IPEDs have bi-atrial enlargement that normalises with allometric scaling, suggesting that increased size is, in part, associated with increased body size. The lower LA and RA reservoir and conduit strain and greater absolute bi-atrial structural parameters in current than non-users of IPEDs suggests pathological adaptation with IPED use, although the similarity in these parameters between past and non-users suggests reversibility of pathological changes with withdrawal.

3-Dimensional Strain Analysis of Hypertrophic Cardiomyopathy: Insights From the NHLBI International HCM Registry

BACKGROUND

Abnormal global longitudinal strain (GLS) has been independently associated with adverse cardiac outcomes in both obstructive and nonobstructive hypertrophic cardiomyopathy.

OBJECTIVES

The goal of this study was to understand predictors of abnormal GLS from baseline data from the National Heart, Lung, and Blood Institute (NHLBI) Hypertrophic Cardiomyopathy Registry (HCMR).

METHODS

The study evaluated comprehensive 3-dimensional left ventricular myocardial strain from cine cardiac magnetic resonance in 2,311 patients from HCMR using in-house validated feature-tracking software. These data were correlated with other imaging markers, serum biomarkers, and demographic variables.

RESULTS

Abnormal median GLS (> -11.0%) was associated with higher left ventricular (LV) mass index (93.8 ± 29.2 g/m2 vs 75.1 ± 19.7 g/m2; P < 0.0001) and maximal wall thickness (21.7 ± 5.2 mm vs 19.3 ± 4.1 mm; P < 0.0001), lower left (62% ± 9% vs 66% ± 7%; P < 0.0001) and right (68% ± 11% vs 69% ± 10%; P < 0.01) ventricular ejection fractions, lower left atrial emptying functions (P < 0.0001 for all), and higher presence and myocardial extent of late gadolinium enhancement (6 SD and visual quantification; P < 0.0001 for both). Elastic net regression showed that adjusted predictors of GLS included female sex, Black race, history of syncope, presence of systolic anterior motion of the mitral valve, reverse curvature and apical morphologies, LV ejection fraction, LV mass index, and both presence/extent of late gadolinium enhancement and baseline N-terminal pro-B-type natriuretic peptide and troponin levels.

CONCLUSIONS

Abnormal strain in hypertrophic cardiomyopathy is associated with other imaging and serum biomarkers of increased risk. Further follow-up of the HCMR cohort is needed to understand the independent relationship between LV strain and adverse cardiac outcomes in hypertrophic cardiomyopathy.

Prognostic value of global longitudinal strain in hypertrophic cardiomyopathy: A systematic review and meta-analysis

BACKGROUND

As previously reported, impairment of left ventricular global longitudinal strain (LVGLS) is associated with myocardial fibrosis, arrhythmias, and heart failure in hypertrophic cardiomyopathy (HCM) patients.

HYPOTHESIS

This study aimed to estimate the association between LVGLS measured by echocardiography and major adverse cardiovascular events (MACE) in patients with HCM.

METHODS

Pubmed, Embase, Scopus, and Cochrane Library databases were systematically searched for evaluating the difference of LVGLS between MACE and non-MACE and the relevance of LVGLS and MACE in HCM patients, mean difference (MD), and pooled hazard ratios (HR) with 95% confidence interval (CI) were calculated. Publication bias was detected by funnel plots and Egger's test, and trim-and-fill analysis was employed when publication bias existed.

RESULTS

A total of 13 studies reporting 2441 HCM patients were included in this meta-analysis. Absolute value of LVGLS was lower in the group of HCM with MACE (MD = 2.74, 95% CI: 2.50-2.99, p < .001; I²  = 0, p = .48). In the pooled unadjusted model, LVGLS was related to MACE (HR = 1.14, 95% CI: 1.06-1.22, p < .05, I²  = 58.4%, p < .01) and there is a mild heterogeneity, and sensitivity analysis showed stable results. In the pooled adjusted model, LVGLS was related to MACE (HR = 1.12, 95% CI: 1.08-1.16, p < .05; I²  = 0%, p = .442). Egger's tests showed publication bias, and trim-and-fill analysis was applied, with final results similar to the previous and still statistically significant.

CONCLUSION

The meta-analysis suggested that impaired LVGLS was associated with poor prognosis in HCM patients.

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.

Predictors of Major Atrial Fibrillation Endpoints in the National Heart, Lung, and Blood Institute HCMR

OBJECTIVES

This study sought to identify predictors of major clinically important atrial fibrillation endpoints in hypertrophic cardiomyopathy.

BACKGROUND

Atrial fibrillation (AF) is a common morbidity associated with hypertrophic cardiomyopathy (HCM). The HCMR (Hypertrophic Cardiomyopathy Registry) trial is a prospective natural history study of 2,755 patients with HCM with comprehensive phenotyping.

METHODS

All patients received yearly telephone follow-up. Major AF endpoints were defined as requiring electrical cardioversion, catheter ablation, hospitalization for >24 h, or clinical decisions to accept permanent AF. Penalized regression via elastic-net methodology identified the most important predictors of major AF endpoints from 46 variables. This was applied to 10 datasets, and the variables were ranked. Predictors that appeared in all 10 sets were then used in a Cox model for competing risks and analyzed as time to first event.

RESULTS

Data from 2,631 (95.5%) patients were available for analysis after exclusions. A total of 127 major AF endpoints events occurred in 96 patients over 33.3 ± 12.4 months. In the final model, age, body mass index (BMI), left atrial (LA) volume index, LA contractile percent (active contraction), moderate or severe mitral regurgitation (MR), and history of arrhythmia the most important. BMI, LA volume index, and LA contractile percent were age-dependent. Obesity was a stronger risk factor in younger patients. Increased LA volume, reduced LA contractile percent, and moderate or severe MR put middle-aged and older adult patients at increased risk.

CONCLUSIONS

The major predictors of major AF endpoints in HCM include older age, high BMI, moderate or severe MR, history of arrhythmia, increased LA volume, and reduced LA contractile percent. Prospective testing of a risk score based on these parameters may be warranted.

The Advantages of New Multimodality Imaging in Choosing the Optimal Management Strategy for Patients with Hypertrophic Cardiomyopathy

In recent years, significant advances have been made in the diagnosis and therapeutic management of hypertrophic cardiomyopathy (HCM) patients, which has led to an important improvement in their longevity and quality of life. The use of multimodality imaging has an essential role in the diagnosis, assessing the regional distribution and severity of the disease, with important prognostic implications. At the same time, imaging contributes to the identification of optimal treatment for patients with hypertrophic cardiomyopathy, whether it is pharmaceutical, interventional or surgical treatment. Novel pharmacotherapies (like myosin inhibitors), minimally invasive procedures (such as transcatheter mitral valve repair, high-intensity focused ultrasound or radiofrequency ablation) and gene-directed approaches, may soon become alternatives for HCM patients. However, there are only few data on the early diagnosis of patients with HCM, in order to initiate treatment as soon as possible, to reduce the risk of sudden cardiac death (SCD). The aim of our review is to highlight the advantages of contemporary imaging in choosing the optimal management strategies for HCM patients, considering the novel therapies which are currently applied or studied for these patients.

Correlation between myocardial strain and adverse remodeling in a non-diabetic model of heart failure following empagliflozin therapy

OBJECTIVES

The sodium-glucose cotransporter type 2 inhibitors reduce mortality and heart failure (HF) hospitalizations. The underlying mechanisms remain unclear but seem to be irrespective of glucose-lowering properties. This study aims to evaluate the impact of empagliflozin on myocardial biomechanics and correlation with markers of adverse remodeling.

METHODS

Following myocardial infarct induction to create a model of HF, 14 pigs were randomly assigned in a 1:1 ratio to receive either empagliflozin 10 mg daily or placebo for 2 months. Speckle-tracking echocardiography (STE) and feature-tracking cardiac magnetic resonance (FTCMR) were performed at baseline and at the end of the study to analyze myocardial deformation. The results were correlated with markers of adverse cardiac remodeling.

RESULTS

Empagliflozin significantly improved STE indices. These parameters significantly correlated with adverse cardiac remodeling. In contrast, FTCMR indices showed only a trend toward improved myocardial deformation and without significant correlation with adverse cardiac remodeling. The correlation between both techniques to assess myocardial deformation was low.

CONCLUSION

Empagliflozin enhances myocardial deformation, assessed by STE techniques, in a non-diabetic porcine model of ischemic HF. This may be related to a mitigation of adverse cardiac remodeling following ischemia reperfusion injury. In contrast, FTCMR technique needs further development and validation.

Time based versus strain based myocardial performance indices in hypertrophic cardiomyopathy, the merging role of left atrial strain

AIMS

The myocardial performance index (MPI) is a time-based index of global myocardial performance. In this study, we sought to compare the prognostic value of the MPI with other strain and remodelling indices in hypertrophic cardiomyopathy (HCM).

METHODS AND RESULTS

We enrolled 126 patients with HCM and 50 age- and sex-matched controls. Along with traditional echocardiographic assessment, MPI, left ventricular global longitudinal strain (LVGLS), E/e' ratio, and total left atrial (LA) global strain (LAS) were also measured. Time-based MPI was calculated from flow or tissue-based pulse wave Doppler (PWD and TDI) as the (isovolumic-relaxation and contraction time)/systolic-time. We used hierarchical clustering and network analysis to better visualize the relationship between parameters. The primary endpoint was the composite of all-cause death, heart transplantation, left ventricular assist device implantation, and clinical worsening. Left ventricular outflow tract (LVOT) obstruction was present in 56% of patients. Compared with controls, patients with HCM had worse LVGLS (-14.0 ± 3.4% vs. -19.6 ± 1.5%), higher E/e' (12.9 ± 7.2 vs. 6.1 ± 1.5), LA volume index (LAVI) (36.4 ± 13.8 ml/m2 vs. 25.6 ± 6.7 ml/m2), and MPI (0.55 ± 0.17 vs. 0.40 ± 0.11 for PWD and 0.59 ± 0.22 vs. 0.46 ± 0.09 for TDI) (all P < 0.001). During a median follow-up of 55 months, 47 endpoints occurred. PWD or TDI-based MPI was not associated with outcome, while LAVI, LAS, LVGLS, and E/e' were (all P < 0.01). On multivariable analysis, LVOT obstruction (P < 0.001), LAS (P < 0.001), and E/e' (P = 0.02) were retained as independent associates. They were in different clusters suggesting complemental relationship between them.

CONCLUSION

Time-based index is less predictive of outcome than strain or tissue Doppler indices. LAS may be a promising prognostic marker in HCM.

Low Left Atrial Strain Is Associated With Adverse Outcomes in Hypertrophic Cardiomyopathy Patients

BACKGROUND

Paroxysmal atrial fibrillation (PAF) and left atrial (LA) structural remodeling are common in hypertrophic cardiomyopathy (HCM) patients, who are also at risk for adverse cardiovascular outcomes.

OBJECTIVE

We assessed whether PAF and/or LA remodeling was associated with adverse outcomes in HCM.

METHODS

We retrospectively studied 45 HCM patients with PAF (PAF group) and 59 HCM patients without atrial fibrillation (AF; no-AF group). LA/left ventricular (LV) function and mechanics were assessed by echocardiography. Patients were followed for development of the composite endpoint comprising heart failure, stroke, and death.

RESULTS

Clinical/demographic characteristics, degree of LV hypertrophy, and E/e' were similar in the two groups The PAF group had significantly higher LA volume, but lower LA ejection fraction (LAEF), LA contractile, and reservoir strain/strain rate than the no-AF group. During follow-up, 27 patients developed the composite endpoint. Incidence of the composite endpoint was similar in the two groups. Absolute values of 23.8% for reservoir strain and 10.2% for conduit strain were the best cutoffs for the composite endpoint, using receiver operating characteristic analysis. Kaplan-Meier survival analysis showed lower event-free survival in patients with reservoir strain ≤23.8% or conduit strain ≤10.2%. Univariate Cox analysis revealed an association between female sex, LAEF, LA reservoir/conduit strain, and LV global longitudinal strain with the composite endpoint. The association between LA reservoir/conduit strain and the composite endpoint persisted after controlling for age, sex, LAEF, and LV global longitudinal strain.

CONCLUSIONS

In this pilot HCM patient study, PAF was associated with a greater degree of LA myopathy, and low LA reservoir and conduit strain were associated with higher risk for adverse cardiovascular outcomes.

Echocardiography in the Diagnosis and Management of Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an inherited condition present in about 1/500 individuals with more than 1500 causative mutations identified in primarily 10 sarcomeric proteins. Although HCM is inherited in an autosomal dominant way, there is often incomplete penetrance and variable phenotype even with the same genotype. It is characterized by a degree of hypertrophy (usually asymmetric), that is, not due to another identifiable cause, as well as variable degrees of myocardial fibrosis and microvascular abnormalities.

Prognostic Value of Global Longitudinal Strain in Hypertrophic Cardiomyopathy: A Systematic Review of Existing Literature

OBJECTIVES

The association of left ventricular global longitudinal strain (LV-GLS) with clinical outcomes in patients with hypertrophic cardiomyopathy (HCM) has been examined in multiple studies. The authors conducted a systematic review aimed at summarizing and critically appraising the current evidence.

BACKGROUND

HCM is a common genetic cardiovascular disease with an estimated prevalence of 1 in 500 patients. LV-GLS derived from speckle tracking echocardiography is a sensitive noninvasive method of assessing regional left ventricular function. Several studies have suggested association of abnormal LV-GLS with outcomes in HCM patients.

METHODS

A computerized literature search of all English language publications in the PubMed and EMBASE databases was made looking at all randomized and nonrandomized studies conducted on patients with HCM where association of LV-GLS with clinical outcomes was studied. We then manually searched the reference lists of included articles. The Preferred Reporting Items for Systematic reviews and Meta-Analyses statement (PRISMA) of reporting systematic reviews was used.

RESULTS

Our search yielded a total of 14 observational studies published between 2009 and 2017 with a total of 3,154 patients with HCM. Eleven of the 14 studies included a composite cardiac outcome which included mortality as their primary outcome of interest and 3 of the 14 studies looked at association of LV-GLS with ventricular arrhythmias and/or implantable cardiac defibrillator discharge. We noted wide variability in inclusion, methodology, follow-up, and consequently effect estimates, which was not conducive to performing a meta-analysis. However, despite the variation, all studies revealed a degree of association of abnormal LV-GLS with poor cardiac outcomes.

CONCLUSIONS

Our systematic review of more than 3000 HCM patients suggests an association of abnormal LV-GLS with adverse composite cardiac outcomes and ventricular arrhythmias.

Left atrial function: evaluation by strain analysis

The left atrium has an important role in modulating left ventricular filling and is an important biomarker of cardiovascular disease and adverse cardiovascular outcomes. While previously left atrial (LA) size was utilised, the role of LA function as a biomarker is increasingly being evaluated, both independently and also in combination with LA size. Strain analysis has been utilised for evaluation of LA function and can be measured throughout the cardiac cycle, thereby enabling the evaluation of LA reservoir, conduit and contractile function. Strain evaluates myocardial deformation while strain rate examines the rate of change in strain. This review will focus on the various types of strain analysis for evaluation of LA function, alterations in LA strain in physiological and pathologic states that alter LA function and finally evaluate its utility as a prognostic marker.

Left ventricular twist in hypertrophic cardiomyopathy : Predictor of nonsustained ventricular tachycardia

BACKGROUND

We investigated the efficacy of clinical and classic echocardiographic parameters in predicting the occurrence of nonsustained ventricular tachycardia (NsVT) in patients with hypertrophic cardiomyopathy (HCM).

METHODS

The study comprised 59 patients with HCM (47 male, [80%]; mean age, 48.48 ± 14.16 years). Clinical, electrocardiographic, as well as classic two-dimensional and speckle-tracking echocardiography (STE) data were collected. All patients had Holter monitoring within 24-72 h of the echocardiographic examination. NsVT was defined as three or more consecutive premature wide QRS complexes with a heart rate of > 100 bpm. The patient population was categorized into groups based on the occurrence or absence of NsVT on the 24-h Holter recordings.

RESULTS

NsVT was observed in 17 patients (29%). In these patients, higher twist (14.4 ± 3.8 vs.18 ± 7.9; p = 0.02), higher apical rotation (8.7 ± 4.2 vs. 12.2 ± 7; p = 0.02), higher sudden cardiac death risk score (4.4 ± 2.2 vs. 7 ± 3.3; p = 0.007), and decreased global longitudinal peak strain (GLPS; -12.8 ± 3.1 vs. -10.6 ± 2.8; p = 0.014) were observed. In the multivariate logistic regression analysis, including GLPS and twist, GLPS (Odds Ratio [OR]: 1.406; 95% CI: 1.087-1.818; p = 0.009) and twist (OR: 1.236; 95% CI: 1.056-1.446; p = 0.008) were found to be independent predictors of NsVT. In the receiver operating characteristic curve analysis, GLPS < -11.9% predicted NsVT with 82% sensitivity and 60% specificity (area under the curve [AUC]: 0.70; p = 0.014) and twist > 15.2° predicted NsVT with 70% sensitivity and 58% specificity (AUC: 0.69; p = 0.027).

CONCLUSION

Decreased GLPS and increased twist were predictive of NsVT in HCM patients. Parameters that can easily be measured with STE can help detect patients who may develop arrhythmia.

Role of Global Longitudinal Strain in Predicting Outcomes in Hypertrophic Cardiomyopathy

Global longitudinal strain (GLS) is a sensitive indicator of global left ventricular function particularly in those with normal ejection fraction. We examined the potential value of GLS in predicting outcomes in hypertrophic cardiomyopathy (HC). Conventional and strain echocardiography was performed in 400 patients with HC followed for a median 3.1 years (interquartile range 1.2 to 5.6). Peak systolic strain from 3 apical views was averaged to calculate GLS. Patients were divided based on a previously published cutoff value of -16%. Additionally, we identified 4 HC subgroups based on GLS: GLS ≤ -20%, -20% < GLS ≤ -16%, -16% < GLS ≤ -10%, and GLS > -10%. The primary end point was a composite of new-onset sustained ventricular tachycardia/fibrillation, heart failure, cardiac transplantation, and all-cause death. Patients with GLS > -16% had significantly more events (17% vs 7%, p = 0.002). In the 4-group analysis, event rates increased with worsening GLS (5%, 7%, 14%, and 33%, respectively, p = 0.001). Event-free survival was significantly superior in those with GLS ≤ -16% versus GLS > -16% (p = 0.004); similarly, GLS > -10% portended a significantly worse event-free survival compared with each of the other 3 groups (p <0.01 for all pairwise comparisons). By univariate and multivariate Cox regression analysis, GLS remained significantly associated with the composite end point. GLS > -10% had 4 times the risk of events compared with GLS ≤ -16% (p = 0.006). In conclusion, echo-based GLS is independently associated with outcomes in HC. Patients with GLS > -10% have significantly higher event rates.

Left Atrial Size and Function in Hypertrophic Cardiomyopathy Patients and Risk of New-Onset Atrial Fibrillation

BACKGROUND

The value of left atrial (LA) diameter, volume, and strain to risk stratify hypertrophic cardiomyopathy patients for new-onset atrial fibrillation (AF) was explored.

METHODS AND RESULTS

A total of 242 hypertrophic cardiomyopathy patients without AF history were evaluated by (speckle-tracking) echocardiography. During mean follow-up of 4.8±3.7 years, 41 patients (17%) developed new-onset AF. Multivariable analysis showed LA volume (≥37 mL/m²; hazard ratio, 2.68; 95% confidence interval, 1.30-5.54; P=0.008) and LA strain (≤23.4%; hazard ratio, 3.22; 95% confidence interval, 1.50-6.88; P=0.003), but not LA diameter (≥45 mm; hazard ratio, 1.67; 95% confidence interval, 0.84-3.32; P=0.145), as independent AF correlates. Importantly, 59% (n=24) of AF events occurred despite a baseline LA diameter <45 mm, observed in 185 patients. In this patient subset, LA strain (area under the curve 0.73) and LA volume (area under the curve 0.83) showed good predictive value for new-onset AF. Furthermore, patients with LA volume <37 versus ≥37 mL/m² and LA strain >23.4% versus ≤23.4% had superior 5-year AF-free survival of 93% versus 80% (P=0.003) and 98% versus 74% (P=0.002), respectively. Importantly, LA volume <37 mL/m² and strain >23.4% yielded high negative predictive value (93% and 98%, respectively) for new-onset AF. Likelihood ratio test indicated incremental value of LA volume assessment (P=0.011) on top of LA diameter to predict new-onset AF in hypertrophic cardiomyopathy patients with LA diameter <45 mm, which tended to increase further by addition of LA strain (P=0.126).

CONCLUSIONS

LA diameter, volume, and strain all relate to new-onset AF in hypertrophic cardiomyopathy patients. In patients with normal LA size, however, both LA volume and strain further refine risk stratification for new-onset AF.

Left atrial function and phenotypes in asymmetric hypertrophic cardiomyopathy

BACKGROUND

Few studies have analyzed changes in left atrial (LA) function associated with different phenotypes of asymmetric hypertrophic cardiomyopathy (HCM). We sought to demonstrate the association of impairments in LA function with disease phenotype in patients with obstructive and nonobstructive HCM.

METHODS

From Stanford Cardiomyopathy Registry, we randomly selected 50 age-/sex-matched healthy controls, 35 patients with nonobstructive HCM (HCM 1), 35 patients with obstructive HCM (HCM 2), and 35 patients with obstructive HCM requiring septal reduction therapy (HCM 3). Echocardiography was performed to evaluate left ventricular (LV) strain as well as LA function including LA emptying fraction and LA strain.

RESULTS

The mean age was 51±14 years and 57% were male. LA volume index differed among all four predefined groups (25.6±6.7 mL/m² in controls, 32.2±13.3 mL/m² in HCM 1, 42.0±12.9 mL/m² in HCM 2, 52.4±15.2 mL/m² for HCM 3, and P<.05 all between groups). All measurement of LA function was impaired in patients with HCM than controls. Total and passive LA function was further impaired in HCM 2 or 3 compared with HCM 1, while active LA function was not different among the three groups. Among LV strains, only septal longitudinal strain differed among all groups (-18.5±1.9% in controls, -14.5±1.9% in HCM 1, -13.3±1.8% in HCM 2, -11.6±2.3% in HCM 3, and P<.05 all between groups).

CONCLUSIONS

LA function was impaired in patients with HCM even in minimally symptomatic nonobstructive phenotype. Total and passive LA function was further impaired in patients with obstructive HCM.

Dyssynchronization reduces dynamic obstruction without affecting systolic function in patients with hypertrophic obstructive cardiomyopathy: a pilot study

Dyssynchrony from biventricular pacing (BiV) can reduce dynamic obstruction in hypertrophic obstructive cardiomyopathy (HOCM), but its consequences on the left ventricular (LV) systolic function are unknown. We evaluate changes in LV systolic function and assess the effectiveness of BiV in HOCM. Thirteen patients with HOCM (55 [33/75] years, five males) received a BiV device and underwent 2D transthoracic echocardiography before the implantation and at 12 months follow-up. Global longitudinal and radial strain, and the timing of segmental displacement curves were measured by commercial speckle-tracking software to assess LV systolic function and dyssynchrony. Peak gradient in the LV outflow tract (LVOT) significantly decreased from 80 [51/100] to 30 [5/66] mmHg (p = 0.005). LV global strain was preserved from baseline to follow-up: 35.1 [20.2/43.8] % vs. 32.6 [27.1/44.1] %, p = NS (radial), and -16.6 [-19.1/-14.4] % vs. -15.7 [-17.0/-14.2] %, p = NS (longitudinal). Dyssynchrony analysis using displacement curves showed inversion of wall motion timing with earlier displacement of the lateral wall at follow-up only in patients with reduction in LVOT gradient. BiV reduces LVOT obstruction in patients with HOCM when dyssynchronization of LV motion and inversion of the timing of LV wall activation are reached. Notably, this does not lead to further deterioration of LV systolic function at mid-term follow-up.

Effect of Left Ventricular Outflow Tract Obstruction on Left Atrial Mechanics in Hypertrophic Cardiomyopathy

Left atrial (LA) volumes are known to be increased in hypertrophic cardiomyopathy (HCM) and are a predictor of adverse outcome. In addition, LA function is impaired and is presumed to be due to left ventricular (LV) diastolic dysfunction as a result of hypertrophy and myocardial fibrosis. In the current study, we assess the incremental effect of outflow tract obstruction (and concomitant mitral regurgitation) on LA function as assessed by LA strain. Patients with HCM (50 obstructive, 50 nonobstructive) were compared to 50 normal controls. A subset of obstructive patients who had undergone septal myectomy was also studied. Utilising feature-tracking software applied to cardiovascular magnetic resonance images, LA volumes and functional parameters were calculated. LA volumes were significantly elevated and LA ejection fraction and strain were significantly reduced in patients with HCM compared with controls and were significantly more affected in patients with obstruction. LA volumes and function were significantly improved after septal myectomy. LVOT obstruction and mitral regurgitation appear to further impair LA mechanics. Septal myectomy results in a significant reduction in LA volumes, paralleled by an improvement in function.

The prognostic value of standardized reference values for speckle-tracking global longitudinal strain in hypertrophic cardiomyopathy

Speckle-tracking left ventricular global longitudinal strain (GLS) assessment may provide substantial prognostic information for hypertrophic cardiomyopathy (HCM) patients. Reference values for GLS have been recently published. We aimed to evaluate the prognostic value of standardized reference values for GLS in HCM patients. An analysis of HCM clinic patients who underwent GLS was performed. GLS was defined as normal (more negative or equal to -16%) and abnormal (less negative than -16%) based on recently published reference values. Patients were followed for a composite of events including heart failure hospitalization, sustained ventricular arrhythmia, and all-cause death. The power of GLS to predict outcomes was assessed relative to traditional clinical and echocardiographic variables present in HCM. 79 HCM patients were followed for a median of 22 months (interquartile range 9-30 months) after imaging. During follow-up, 15 patients (19%) met the primary outcome. Abnormal GLS was the only echocardiographic variable independently predictive of the primary outcome [multivariate Hazard ratio 5.05 (95% confidence interval 1.09-23.4, p = 0.038)]. When combined with traditional clinical variables, abnormal GLS remained independently predictive of the primary outcome [multivariate Hazard ratio 5.31 (95 % confidence interval 1.18-24, p = 0.030)]. In a model including the strongest clinical and echocardiographic predictors of the primary outcome, abnormal GLS demonstrated significant incremental benefit for risk stratification [net reclassification improvement 0.75 (95 % confidence interval 0.21-1.23, p < 0.0001)]. Abnormal GLS is an independent predictor of adverse outcomes in HCM patients. Standardized use of GLS may provide significant incremental value over traditional variables for risk stratification.

Evaluation of subtle left ventricular systolic abnormalities in adult patients with hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM), an auto-somal dominant disorder due to mutation of genes encoding sarcomeric proteins, leads to left ventricular diastolic dysfunction. Recently, the research in this area suggests that systolic dysfunction exists in the patients with HCM even though traditional measures of systolic dysfunction are normal. So, we carried out this study to determine global systolic dysfunction in patients with HCM.

MATERIALS AND METHODS

A total of 18 patients, diagnosed with HCM according to echocardiography parameters, that is thickness of interventricular septum/posterior wall thickness >1.3 or hypertrophy involving apex only with or without left ventricular outflow tract obstruction, were included in the study and were compared with normal age-matched controls. We measured torsion and strain imaging by 2-dimensional echocardiography as well as strain imaging by tissue Doppler echocardiography.

RESULT

The results of the study showed that there was considerable increased torsion in patients with HCM as compared to normal subjects (16.61±7.43 vs. 10.42±4.73, p=0.006). Tissue Doppler indices-systolic annular velocity (7.7±0.7 vs. 8.7±1.00, p=0.012) and lateral wall E/E' (12.52±5.27 vs. 6.66±1.67, p<0.001) were significantly different in patients with HCM and normal subjects. The average systolic strain and strain rate as well as diastolic strain rate were significantly different in both the groups when strain imaging was performed by tissue Doppler echocardiography. We also observed significantly reduced global longitudinal, circumferential and radial strain in patients with HCM when strain analysis was carried out with 2-dimensional speckle tracking echocardiography.

CONCLUSION

The global subtle systolic dysfunction, as measured by left ventricular torsion and strain imaging, is present in patients with HCM even though traditional measure of systolic dysfunction is normal.

Left atrial enlargement and reduced atrial compliance occurs early in Fabry cardiomyopathy

BACKGROUND

Fabry disease is associated with left ventricular hypertrophy (LVH) and myocardial fibrosis. The aim of this study was to evaluate left atrial (LA) size and function using tissue Doppler-derived strain in patients with Fabry disease.

METHODS

Echocardiography was performed in 33 Fabry patients (14 without LVH, 19 with LVH) before commencement of enzyme replacement therapy, and results were compared with those from age-matched and gender-matched controls (n=28 and n=38, respectively). Atrial strain and strain rate were measured from four segments in the apical four-chamber and two-chamber views of the LA, and global values were calculated. Systolic strain, systolic strain rate, early diastolic strain rate, and late diastolic strain rate were measured. Phasic LA volumes and fractions were calculated. Mitral inflow and tissue Doppler E' velocities were used to estimate left ventricular (LV) diastolic function.

RESULTS

LA volume was increased in Fabry patients, even in the absence of LVH. Importantly, diastolic function was normal in this subgroup without LVH, with E' velocities similar to those in controls. LA systolic strain and early diastolic strain rate were selectively reduced in Fabry patients with LVH and reflect reductions in LA and LV relaxation, respectively, consequent to increased LV mass. However, independent of LVH, both Fabry groups had significant reductions in systolic strain rate and increased LA stiffness index.

CONCLUSIONS

Fabry disease is associated with LA enlargement and reduced atrial compliance that occurs before the development of LVH. This suggests that Fabry cardiomyopathy may not only cause ventricular hypertrophy and fibrosis but also alters atrial myocardial properties early in the disease process. Consequently, measurements of LA size and function may be useful in the early diagnosis of Fabry disease, before the development of LVH.

Comparison of left atrial phasic function in hypertrophic cardiomyopathy versus systemic hypertension using strain rate imaging

The aim of this study was to determine if left atrial (LA) phasic function evaluated by Doppler tissue imaging-derived strain and strain rate would be differentially decreased in patients with hypertrophic cardiomyopathy (HC) compared to patients with hypertension and to normal controls. Thirty-seven patients with HC were compared to 44 patients with systemic hypertension (SH) and 65 normal controls using transthoracic echocardiography. Maximal and minimal LA volume and LA volume just before active atrial contraction (pre-P LA volume) were measured, and phasic LA volumes were calculated. Global and segmental systolic strain rate, early diastolic strain rate, and late diastolic strain rate (A-Sr) and strain were measured from Doppler tissue imaging. Left ventricular mass was increased in the HC and SH groups compared to normal controls, but diastolic dysfunction was greater in the HC group. LA volumes were increased in patients with HC compared to those with SH and to normal controls, with corresponding reductions in A-Sr and atrial strain in the HC group. In contrast, only early diastolic strain rate was decreased in the SH group compared to controls. A-Sr remained reduced in patients with HC compared to the SH group, even after adjusting for left ventricular mass. When left ventricular mass, parameters of diastolic function (peak E and E' velocity), and the effect of patient group (SH vs HC) were examined in a stepwise regression model, patient group (SH vs HC) was the only independent determinant of A-Sr. In conclusion, HC results in LA enlargement with reduced LA phasic function that is reflected in reductions in A-Sr and atrial strain. Atrial enlargement is a likely consequence of the greater diastolic dysfunction in the HC group.

Personalized echocardiography: clinical applications of advanced echocardiography and future directions

Future cardiology practice will be increasingly individualized, and thus to maintain its central role, echocardiography must keep pushing to expand the boundaries of real-time data acquisition from tissue and fluid motion, and yet still provide efficient and timely data analysis that leads to succinct, clear clinical recommendations tailored to each person in our care. In this article, recent efforts to expand echocardiography techniques into an era of increasingly personalized cardiology, including advances in color-coded tissue Doppler, 3D echocardiography and complex exercise stress echocardiography are described. The common metric for success in each of these efforts is the development of robust and institutionally supportable echocardiography protocols for specific cardiology disease populations that currently may be underdiagnosed and/or undertreated. The common result in each case should be the creation of new guidelines that can supplement the current standard protocols advocated by professional echocardiography organizations.

Atrial Fibrillation in Hypertrophic Obstructive Cardiomyopathy - Antiarrhythmics, Ablation and More!

Hypertrophic cardiomyopathy (HCM) is a genetic disease of the cardiac sarcomere with an autosomal dominant pattern of inheritance. Patients with HCM are at high risk of developing atrial fibrillation (AF) particularly in the setting of advanced diastolic dysfunction and left atrial enlargement. AF is a marker of increased mortality and morbidity and results in a significant reduction in quality of life. Antiarrhythmic medications improve symptoms and reduce AF recurrence, but few are safe and there exists little data to guide their long-term use in HCM. Non-pharmacologic approaches have emerged and have equal or greater efficacy than pharmacologic approaches. Although these approaches are promising, the long-term impact on atrial function needs to be carefully studied as it may impact quality of life in patients that age in the setting of a progressive diastolic disease disorder. Nonetheless, with the significant impact of AF in HCM, rhythm control strategies are often required. The understanding of rhythm control strategies in HCM, an often rapidly progressive diastolic dysfunction disorder, may provide insight in how to treat the much more prevalent AF patient with hypertensive cardiomyopathy. Regardless of treatment strategy (rhythm or rate control) patients are a moderate to high risk of thromboembolism and until data are available to suggest otherwise require long-term warfarin anticoagulation.