Left ventricular markers of mortality and ventricular arrhythmias in heart failure patients with cardiac resynchronization therapy

Heart Failure after Transcatheter Aortic Valve Implantation: Application of the Most Impactful Strain Imaging Techniques

•LBBB is the most common TAVI-induced conduction abnormality. •Strain imaging can assist with determining the etiology of heart failure after TAVI. •Strain imaging can help predict response to CRT.

Global constructive work is associated with ventricular arrhythmias after cardiac resynchronization therapy

AIMS

Non-invasive left ventricular (LV) pressure-strain loops provide a novel method for quantifying myocardial work by incorporating LV pressure in measurements of myocardial deformation. Early studies suggest that myocardial work parameters such as global constructive work (GCW) could be useful and reliable in arrhythmia prediction, particularly in patients undergoing cardiac resynchronization therapy (CRT). The aim of this study was to evaluate whether the magnitude of GCW was associated with the occurrence of ventricular arrhythmias in patients after CRT.

METHODS AND RESULTS

Patients on guideline-recommended treatment with a CRT defibrillator (CRT-D) were evaluated by 2D speckle-tracking echocardiography including measurements of GCW at least 6 months after implantation. The primary outcome was a composite of appropriate defibrillator therapy and sustained ventricular arrhythmia under the monitor zone. A total of 162 patients [mean age 66 years (±10), 122 males (75%)] were included. Sixteen (10%) patients experienced the primary outcome during a median follow-up of 18 months (interquartile range: 12-25) after the performance of index echocardiography. Patients with a below-median GCW (<1473 mmHg%) had a hazard ratio (HR) for the outcome of 8.14 [95% confidence interval (CI): 1.83-36.08], P = 0.006 compared with patients above the median in a univariate model and remained an independent predictor after multivariate adjustment for the estimated glomerular filtration rate and QRS duration [HR 4.75 (95% CI: 1.01-22.28), P < 0.05].

CONCLUSION

In patients treated with CRT-D, a GCW below median level was associated with a five-fold increase in the risk of ventricular arrhythmias.

Strain Imaging and Ventricular Arrhythmia

Ventricular arrhythmia is one of the main causes of sudden cardiac death. Hence, identifying patients at risk of ventricular arrhythmias and sudden cardiac death is important but can be challenging. The indication for an implantable cardioverter defibrillator as a primary preventive strategy relies on the left ventricular ejection fraction as a measure of systolic function. However, ejection fraction is flawed by technical constraints and is an indirect measure of systolic function. There has, therefore, been an incentive to identify other markers to optimize the risk prediction of malignant arrhythmias to select proper candidates who could benefit from an implantable cardioverter defibrillator. Speckle-tracking echocardiography allows for a detailed assessment of cardiac mechanics, and strain imaging has repeatedly been shown to be a sensitive technique to identify systolic dysfunction unrecognized by ejection fraction. Several strain measures, including global longitudinal strain, regional strain, and mechanical dispersion, have consequently been proposed as potential markers of ventricular arrhythmias. In this review, we will provide an overview of the potential use of different strain measures in the context of ventricular arrhythmias.

Considering Both GLS and MD for a Prognostic Value in Non-ST-Segment Elevated Acute Coronary Artery Syndrome

Global longitudinal strain (GLS) and mechanical dispersion (MD), as determined by 2D speckle tracking echocardiography, have been demonstrated to be reliable indicators of prognosis in a variety of cardiovascular illnesses. There are not many papers that discuss the prognostic significance of GLS and MD in a population with non-ST-segment elevated acute coronary syndrome (NSTE-ACS). Our study objective was to examine the predictive utility of the novel GLS/MD two-dimensional strain index in NSTE-ACS patients. Before discharge and four to six weeks later, echocardiography was performed on 310 consecutive hospitalized patients with NSTE-ACS and effective percutaneous coronary intervention (PCI). Cardiac mortality, malignant ventricular arrhythmia, or readmission owing to heart failure or reinfarction were the major end points. A total of 109 patients (35.16%) experienced cardiac incidents during the follow-up period (34.7 ± 8 months). The GLS/MD index at discharge was determined to be the greatest independent predictor of composite result by receiver operating characteristic analysis. The ideal cut-off value was -0.229. GLS/MD was determined to be the top independent predictor of cardiac events by multivariate Cox regression analysis. Patients with an initial GLS/MD > -0.229 that deteriorated after four to six weeks had the worst prognosis for a composite outcome, readmission, and cardiac death according to a Kaplan-Meier analysis (all p < 0.001). In conclusion, the GLS/MD ratio is a strong indicator of clinical fate in NSTE-ACS patients, especially if it is accompanied by deterioration.

What Strain Analysis Adds to Diagnosis and Prognosis in Heart Failure Patients

Heart failure (HF) is a common disease that requires appropriate tools to correctly predict cardiovascular outcomes. Echocardiography represents the most commonly used method for assessing left ventricular ejection fraction and a cornerstone in the detection of HF, but it fails to procure an optimal level of inter-observer variability, leading to unsatisfactory prediction of cardiovascular outcomes. In this review, we discuss emerging clinical tools (global longitudinal strain of the left ventricle, the right ventricle, and the left atrium) that permitted an improvement in the diagnosis and ameliorated the risk stratification across different HF phenotypes. The review analyzes the speckle-tracking contributions to the field, discussing the limitations and advantages in clinical practice.

ACR Appropriateness Criteria® Dyspnea-Suspected Cardiac Origin (Ischemia Already Excluded): 2021 Update

Dyspnea is the symptom of perceived breathing discomfort and is commonly encountered in a variety of clinical settings. Cardiac etiologies of dyspnea are an important consideration; among these, valvular heart disease (Variant 1), arrhythmia (Variant 2), and pericardial disease (Variant 3) are reviewed in this document. Imaging plays an important role in the clinical assessment of these suspected abnormalities, with usually appropriate procedures including resting transthoracic echocardiography in all three variants, radiography for Variants 1 and 3, MRI heart function and morphology in Variants 2 and 3, and CT heart function and morphology with intravenous contrast for Variant 3. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Myocardial electrophysiological and mechanical changes caused by moderate hypothermia-A clinical study

Moderate hypothermia has been used to improve outcomes in comatose out-of-hospital cardiac arrest survivors during the past two decades, although the effects remain controversial. We have recently shown in an experimental study that myocardial electrophysiological and mechanical relationships were altered during moderate hypothermia. Electromechanical window positivity increased, and electrical dispersion of repolarization decreased, both of which are changes associated with decreased arrhythmogenicity in clinical conditions. Mechanical dispersion, a parameter also linked to arrhythmic risk, remained unaltered. Whether corresponding electrophysiological and mechanical changes occur in humans during moderate hypothermia, has not been previously explored. Twenty patients with normal left ventricular function were included. Measurements were obtained at 36 and 32°C prior to ascending aortic repair while on partial cardiopulmonary bypass and at 36°C after repair. Registrations were performed in the presence of both spontaneous and comparable paced heart rate during standardized loading conditions. The following electrical and mechanical parameters were explored: (1) Electromechanical window, measured as time difference between mechanical and electrical systole, (2) dispersion of repolarization from ECG T-wave, and (3) mechanical dispersion, measured as segmental variation in time to peak echocardiographic strain. At moderate hypothermia, mechanical systolic prolongation (425 ± 43-588 ± 67 ms, p < 0.001) exceeded electrical systolic prolongation (397 ± 49-497 ± 79 ms, p < 0.001), whereby, electromechanical window positivity increased (29 ± 30-86 ± 50 ms, p < 0.001). Dispersion of repolarization and mechanical dispersion remained unchanged. Corresponding electrophysiological and mechanical relationships were present at comparable paced heart rates. After rewarming, the increased electromechanical window was reversed in the presence of both spontaneous and paced heart rates. Moderate hypothermia increased electromechanical window positivity, while dispersion of repolarization and mechanical dispersion remained unchanged. This impact of hypothermia may be clinically relevant for selected groups of patients after cardiac arrest.

Prognosis of chronic Chagas heart disease and other pending clinical challenges

In this chapter, the main prognostic markers of Chagas heart disease are addressed, with an emphasis on the most recent findings and questions, establishing the basis for a broad discussion of recommendations and new approaches to managing Chagas cardiopathy. The main biological and genetic markers and the contribution of the electrocardiogram, echocardiogram and cardiac magnetic resonance are presented. We also discuss the most recent therapeutic proposals for heart failure, thromboembolism and arrhythmias, as well as current experience in heart transplantation in patients suffering from severe Chagas cardiomyopathy. The clinical and epidemiological challenges introduced by acute Chagas disease due to oral contamination are discussed. In addition, we highlight the importance of ageing and comorbidities in influencing the outcome of chronic Chagas heart disease. Finally, we discuss the importance of public policies, the vital role of funding agencies, universities, the scientific community and health professionals, and the application of new technologies in finding solutions for better management of Chagas heart disease.

Heart failure with recovered ejection fraction and the utility of defibrillator therapy: a review

Heart failure with recovered ejection fraction (HFrecEF) involves those who have previously had reduced cardiac function that has subsequently improved. However, there is not a single definition of this phenomenon and recovery of cardiac function in terms of left ventricular ejection fraction (LVEF) itself does not necessarily correlate with remission from the detrimental physiology of heart failure (HF) and its consequences. There is also the question of the utility of defibrillators in these patients, and whether they should be replaced at the time of battery depletion. To address this, several studies have shown specific predictors of ensuing LVEF recovery, including patient demographics, co‐morbidities, and medication use, as well as predictors of ventricular arrhythmias (VA) following LVEF recovery. Recent studies have also shown novel imaging parameters that may aid in predicting which patients would have a higher risk of these arrhythmias. Additional data describe a small, yet appreciable risk of VA, in addition to appropriate shocks as well. In this review, we describe predictors of LVEF recovery, carefully analyse and characterize the continued risk for VA and appropriate shocks following LVEF recovery, and explore additional novel modalities that may aid in decision‐making.

Speckle tracking strain and ECG heterogeneity correlate in transcatheter aortic valve replacement-induced left bundle branch blocks and right ventricular paced rhythms

Objective

Transcatheter aortic valve replacement (TAVR) complications include left bundle branch block (LBBB) and right ventricular paced rhythm (RVP). We hypothesised that changes in electrocardiographic heterogeneity would correlate better with speckle tracking strain measures than with left ventricular ejection fraction (LVEF) on transthoracic echocardiogram (TTE) among patients with TAVR-induced conduction abnormalities.

Methods

We reviewed medical records of 446 consecutive patients who underwent TAVR at our institution. Of the 238 patients with 12-lead electrocardiograms (ECGs) that met our inclusion criteria, 58 had pre-TAVR and post-TAVR TTEs adequate for strain assessment. We compared patients who did not have an LBBB or RVP pre-TAVR and post-TAVR (controls, n=11) with patients who developed LBBBs (n=11) and who required RVPs (n=10) post-TAVR. In our study population (n=32, 41% female, mean age 85.8 years), we evaluated QRS complex duration, R-wave heterogeneity (RWH), T-wave heterogeneity (TWH), LVEF, global longitudinal strain (GLS) and mechanical dispersion (MD).

Results

TAVR-induced changes on ECG did not correlate with LVEF. TAVR-induced changes in MD and QRS complex duration correlated among all patients (r=0.4, p=0.04). GLS and RWH correlated among RVP patients (r=0.7, p=0.00003). MD and TWH correlated among LBBB patients (r=0.7, p=0.00004).

Conclusions

In this convenience sample of patients with TAVR-induced conduction abnormalities, RWH and TWH correlated with strain measures but not with LVEF. Strain measures, RWH and TWH may offer additional insights for pre-TAVR evaluation and post-TAVR clinical management.

Burden of Ventricular Arrhythmias in Cardiac Resynchronization Therapy Defibrillation and Implantable Cardioverter-Defibrillator Recipients with Recovered Left Ventricular Ejection Fraction: The Additive Role of Speckle-Tracking Echocardiography

BACKGROUND

Patients with heart failure undergoing cardiac resynchronization therapy with or without defibrillator function may exhibit recovery of left ventricular ejection fraction (LVEF) during follow-up. Mechanical dispersion (MD; the SD of time to peak longitudinal strain by two-dimensional speckle-tracking echocardiography) is a known predictor of life-threatening ventricular arrhythmias (VAs). Relationships among LVEF recovery, changes in MD, and incidence of VA are still not extensively investigated.

METHODS

In this retrospective study, recipients of cardiac resynchronization therapy defibrillation (n = 183) or implantable cardioverter-defibrillators only (n = 87) underwent conventional and speckle-tracking echocardiography, both at baseline and after 10 to 12 months, and were followed clinically. Both a ≥10% increase in LVEF and a final LVEF > 35% defined echocardiographic response (Echo_Resp). Reduction in MD ≥10 msec defined MD response (MD_Resp). Risk for appropriate implantable cardioverter-defibrillator therapy for VAs was assessed using a multivariable Cox hazard model.

RESULTS

The prevalence of Echo_Resp+ and MD_Resp+ was 39% and 46%, respectively. During follow-up (49.8 ± 33.5 months), 74 VA events occurred. The incidence rate (per 100 patient-years) of VAs was lowest in the Echo_Resp+/MD_Resp+ group (1.66%; 95% CI, 0.69%-3.99%), highest in the Echo_Resp-/MD_Resp- group (12.8%; 95% CI, 9.53%-17.2%; P < .0001), and intermediate in the Echo_Resp-/MD_Resp+ (5.5%; 95% CI, 3.3%-9.4%) or Echo_Resp+/MD_Resp- (5.3%; 95% CI, 3.0%-9.4%) group. Multivariable analysis showed that higher MD at follow-up (>71.4 msec) was associated with VAs independent of whether final LVEF was below or above the guideline-reported cutoff of 35% (P < .05).

CONCLUSIONS

Among ICD recipients, improvements in both left ventricular function and MD are associated with reduced risk for VAs. In patients whose follow-up LVEFs improved to >35%, risk for VAs, although substantially decreased, remained elevated in the presence of still elevated MD.

Global longitudinal strain as a prognostic marker in cardiac resynchronisation therapy: A systematic review

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Left ventricular global longitudinal strain (LV GLS) is a sensitive parameter that correlates with myocardial scar burden and fibrosis with potential value in CRT candidates.

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First systematic review evaluating the existing evidence for the prognostic value of LV GLS in patients undergoing CRT implantation.

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Despite significantly abnormal baseline GLS at CRT implantation, there is still a significant association between incrementally worse LV GLS at CRT implantation and prognostic outcomes on long-term follow-up.

Purpose

Cardiac resynchronisation therapy (CRT) has proven mortality benefits for heart failure patients with moderate to severe systolic left ventricular dysfunction and evidence of a left bundle branch block. Determining responders to this therapy can be difficult due to the presence of myocardial fibrosis and scar. Left ventricular global longitudinal strain (LV GLS) is a robust and sensitive measure of myocardial function and fibrosis that has significant prognostic value for a plethora of cardiac pathologies. Our aim was to perform a systematic review of the value of LV GLS for predicting outcomes in patients undergoing CRT.

Methods

A systematic review of the literature was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) protocol for reporting on systematic reviews and meta-analyses. An electronic search of all English, adult publications in EMBASE, MEDLINE/PubMed and the Cochrane Database of Systematic reviews was undertaken.

Results

The search yielded, 9 studies that included 3,981 patients with symptomatic heart failure, undergoing CRT implantation with LV GLS utilised as a predictor of all-cause mortality, cardiovascular death, rehospitalisation, LVAD implantation/ heart transplantation or left ventricular reverse remodelling. Significant heterogeneity was observed in study outcome measures, included populations, LV-GLS cut-offs and follow-up definitions, resulting in the inability to reliably conduct a meta-analyses. Overall, pre-CRT LV GLS was found to be a predictor of outcome post CRT insertion.

Conclusions

In conclusion, all studies implied that incrementally abnormal baseline LV GLS pre-CRT implantation was associated with a long term poorer outcome.

Left ventricular mechanical dispersion in a general population: Data from the Akershus Cardiac Examination 1950 study

AIMS

Increased left ventricular mechanical dispersion by 2D speckle tracking echocardiography predicts ventricular arrhythmias in ischaemic heart disease and heart failure. However, little is known about mechanical dispersion in the general population. We aimed to study mechanical dispersion in the general population and in diseases associated with increased risk of cardiovascular disease.

METHODS AND RESULTS

The present cross-sectional study consists of 2529 subjects born in 1950 included in the Akershus Cardiac Examination (ACE) 1950 study. Global longitudinal strain (GLS) was assessed from 17 strain segments, and mechanical dispersion calculated as the standard deviation of contraction duration of all segments. The cohort was divided according to the median value of mechanical dispersion, and multivariable linear regression models were performed with mechanical dispersion as the dependent variable. The prevalence of coronary artery disease (CAD), hypertension, obesity, and diabetes (P < 0.01 for all) was significantly higher in subjects with supra-median mechanical dispersion. In a multivariable clinical model, CAD (B = 7.05), hypertension (B = 4.15; both P < 0.001), diabetes (B = 3.39), and obesity (B = 1.89; both P < 0.05) were independently associated with increasing mechanical dispersion. When echocardiographic indices were added to the multivariable model, CAD (B = 4.38; P < 0.01) and hypertension (B = 2.86; P < 0.001) remained significant in addition to peak early diastolic tissue velocity e' (B = -2.00), GLS (B = 1.68), and ejection fraction (B = 0.22; P < 0.001 for all).

CONCLUSION

In a general middle-aged population, prevalent CAD and hypertension were associated with increasing mechanical dispersion, possibly indicating elevated risk of fatal arrhythmias and sudden cardiac death. Albeit weaker, systolic and diastolic dysfunction, were also associated with increasing mechanical dispersion.

Left ventricular myocardial deformation pattern, mechanical dispersion, and their relation with electrocardiogram markers in the large population-based STANISLAS cohort: insights into electromechanical coupling

AIMS

Mechanical alterations in patients with electrical conduction abnormalities are reported to have prognostic value in patients with left ventricular asynchrony or long QT syndrome beyond electrocardiogram (ECG) variables. Whether conduction and repolarization patterns derived from ECG are associated with speckle tracking echocardiography parameters in subjects without overt cardiac disease is yet to be investigated. To report ranges of longitudinal deformation according to conduction and repolarization values in a population-based cohort.

METHODS AND RESULTS

One thousand, one hundred, and forty subjects (48.6 ± 14.0 years, 47.7% men) enrolled in the fourth visit of the STANISLAS cohort (Lorraine, France) were studied. Echocardiography strain was performed in all subjects. RR, PR, QRS, and QT intervals were retrieved from digitalized 12-lead ECG. Echocardiographic data were stratified according to quartiles of QRS and QTc duration values. Full-wall global longitudinal strain (GLS) was -21.1 ± 2.5% with a mechanical dispersion (MD) value of 34 ± 12 ms. Absolute GLS value was lower in the longest QRS quartile and shortest QTc quartile (both P < 0.001). Time-to-peak of strain was not significantly different according to QRS duration although significantly higher in patients with higher QTc (P < 0.001). MD was significantly greater in patients with longer QTc (32 ± 12 ms for QTc < 396 ms vs. 36 ± 12 ms for QTc > 421 ms; P = 0.002).

CONCLUSION

Longer QTc is related to increased MD and better longitudinal strain values. In a population-based setting, QRS is not associated with MD, suggesting that echocardiography-based dyssynchrony does not largely overlap with ECG-based dyssynchrony.

Left ventricular mechanical dispersion in ischaemic cardiomyopathy: association with myocardial scar burden and prognostic implications

AIMS

Left ventricular (LV) mechanical dispersion (MD) may result from heterogeneous electrical conduction and is associated with adverse events. The present study investigated (i) the association between LV MD and the extent of LV scar as assessed with contrast-enhanced cardiac magnetic resonance (CMR) and (ii) the prognostic implications of LV MD in patients after ST-segment elevation myocardial infarction.

METHODS AND RESULTS

LV MD was calculated by echocardiography and myocardial scar was analysed on CMR data retrospectively. Infarct core and border zone were defined as ≥50% and 35-50% of maximal signal intensity, respectively. Patients were followed for the occurrence of the combined endpoint (all-cause mortality and appropriate implantable cardioverter-defibrillator therapy). In total, 96 patients (87% male, 57 ± 10 years) were included. Median LV MD was 53.5 ms [interquartile range (IQR) 43.4-62.8]. On CMR, total scar burden was 11.4% (IQR 3.8-17.1%), infarct core tissue 6.2% (IQR 2.0-12.7%), and border zone was 3.5% (IQR 1.5-5.7%). Correlations were observed between LV MD and infarct core (r = 0.517, P < 0.001), total scar burden (r = 0.497, P < 0.001), and border zone (r = 0.298, P = 0.003). In total, 14 patients (15%) reached the combined endpoint. Patients with LV MD >53.5 ms showed higher event rates as compared to their counterparts. Finally, LV MD showed the highest area under the curve for the prediction of the combined endpoint.

CONCLUSION

LV MD is correlated with LV scar burden. In addition, patients with prolonged LV MD showed higher event rates. Finally, LV MD provided the highest predictive value for the combined endpoint when compared with other parameters.

Global longitudinal strain predicts responders after cardiac resynchronization therapy-a systematic review and meta-analysis

To evaluate the association between baseline global longitudinal strain (GLS) and ΔGLS (difference of baseline GLS and follow-up) and cardiac resynchronization therapy (CRT) response defined either with clinical or with echocardiographic characteristics. This meta-analysis was performed in accordance to both the Meta-Analysis of Observational Studies in Epidemiology and Strengthening the Reporting of Observational Studies in Epidemiology guidelines. Two independent investigators performed a comprehensive systematic search in MedLine, EMBASE and Cochrane databases through September 2019 without limitations. Data analysis was performed by using the Review Manager software (RevMan), version 5.3, and Stata 13 software. A p value of less than 0.05 (two-tailed) was considered statistically significant. Twelve studies (1004 patients, mean age 63.8 years old, males 69.4%) provided data on the association of baseline GLS with the response to CRT therapy. We found that CRT responders had significantly better resting GLS values compared with non-responders [GLS mean difference -2.13 (-3.03, -1.23), p < 0.001, I² 78%]. Furthermore, CRT responders had significantly greater improvement of GLS at follow-up compared with non-responders [ΔGLS mean difference -3.20 (-4.95, -1.45), p < 0.001, I² 66%]. These associations remained significant in a subgroup analysis including only studies with similar CRT response definition. In this meta-analysis, we found that CRT responders had a baseline and ΔGLS significantly higher than the non-responders strengthening the central role of GLS as a tool for selecting candidates for CRT. Furthermore, improved GLS values after CRT may be used to better define CRT responders.

Left ventricular global longitudinal strain in predicting CRT response: one more J-shaped curve in medicine

The aim of the study was: (1) to verify the hypothesis that left ventricular global longitudinal strain (LVGLS) may be of additive prognostic value in prediction CRT response and (2) to obtain such a LVGLS value that in the best optimal way enables to characterize potential CRT responders. Forty-nine HF patients (age 66.5 ± 10 years, LVEF 24.9 ± 6.4%, LBBB 71.4%, 57.1% ischemic aetiology of HF) underwent CRT implantation. Transthoracic echocardiography was performed prior to and 15 ± 7 months after CRT implantation. Speckle-tracking echocardiography was performed to assess longitudinal left ventricular function as LVGLS. The response to CRT was defined as a ≥ 15% reduction in the left ventricular end-systolic volume (∆LVESV). Thirty-six (73.5%) patients responded to CRT. There was no linear correlation between baseline LVGLS and ∆LVESV (r = 0.09; p = 0.56). The patients were divided according to the percentile of baseline LVGLS: above 80th percentile; between 80 and 40th percentile; below 40th percentile. Two peripheral groups (above 80th and below 40th percentile) formed “peripheral LVGLS” and the middle group was called “mid-range LVGLS”. The absolute LVGLS cutoff values were − 6.07% (40th percentile) and − 8.67% (80th percentile). For the group of 20 (40.8%) “mid-range LVGLS” patients mean ΔLVESV was 33.3 ± 16.9% while for “peripheral LVGLS” ΔLVESV was 16.2 ± 18.8% (p < 0.001). Among non-ischemic HF etiology, all “mid-range LVGLS” patients (100%) responded positively to CRT (in “peripheral LVGLS”—55% responders; p = 0.015). Baseline LVGLS may have a potential prognostic value in prediction CRT response with relationship of inverted J-shaped pattern. “Mid-range LVGLS” values should help to select CRT responders, especially in non-ischemic HF etiology patients.

Tissue Doppler-Derived Left Ventricular Systolic Velocity Is Associated with Lethal Arrhythmias in Cardiac Device Recipients Irrespective of Left Ventricular Ejection Fraction

BACKGROUND

Life-threatening arrhythmias (LTAs) can trigger sudden cardiac death or provoke implantable cardioverter-defibrillator (ICD) discharges that escalate morbidity and mortality. Longitudinal myofibrils predominate in the subendocardium, which is uniquely sensitive to arrhythmogenic triggers. In this study, we test the hypothesis that mitral annular systolic velocity (S'), a simple routinely obtained tissue Doppler index of LV long-axis systolic function, might predict lethal arrhythmias irrespective of left ventricular ejection fraction (LVEF).

METHODS

This is a retrospective analysis of data from 302 patients (mean age, 68 years; LVEF, 32%; 77% male; 52% ischemic; 35% primary prevention; and 53% cardiac resynchronization therapy defibrillator [CRT-D]) who were followed up (median, 15 months) at two centers after receipt of an ICD or CRT-D for diverse indications. S', averaged from tissue Doppler-derived medial and lateral mitral annular velocities, was correlated with the primary outcome of time to sustained ventricular tachycardia (VT) or fibrillation (VF) needing device therapy.

RESULTS

The median S' was 5.1 (interquartile range, 4.0-6.2) cm/sec and lower in CRT-D than ICD subjects (4.5 [3.8-5.6] cm/sec vs 5.5 [4.8-6.8] cm/sec, P < .001). Fifty-six (19%) subjects had LTA. Each 1 cm/sec higher S' correlated to a 30% decreased risk of LTA (hazard ratio = 0.70; 95% CI, 0.57-0.87; P = .001) independently of age, sex, β-blocker use, center, ICD use, and LVEF. Adding S' to the baseline Cox model improved net reclassification (P = .02). An S' > 5.6 cm/sec was the best cutoff and linked to a 58% lower LTA risk than an S' ≤ 5.6 cm/sec (95% CI, 0.23-0.85; P = .02).

CONCLUSIONS

A higher S' is associated with a reduced probability of LTA in cardiac device recipients irrespective of LVEF and may have the potential to be used clinically to titrate medical, device, and ablative therapies to mitigate future arrhythmic risk.

Septal contraction predicts acute haemodynamic improvement and paced QRS width reduction in cardiac resynchronization therapy

AIMS

Three distinct septal contraction patterns typical for left bundle branch block may be assessed using echocardiography in heart failure patients scheduled for cardiac resynchronization therapy (CRT). The aim of this study was to explore the association between these septal contraction patterns and the acute haemodynamic and electrical response to biventricular pacing (BIVP) in patients undergoing CRT implantation.

METHODS AND RESULTS

Thirty-eight CRT candidates underwent speckle tracking echocardiography prior to device implantation. The patients were divided into two groups based on whether their septal contraction pattern was indicative of dyssynchrony (premature septal contraction followed by various amount of stretch) or not (normally timed septal contraction with minimal stretch). CRT implantation was performed under invasive left ventricular (LV) pressure monitoring and we defined acute CRT response as ≥10% increase in LV dP/dtmax. End-diastolic pressure (EDP) and QRS width served as a diastolic and electrical parameter, respectively. LV dP/dtmax improved under BIVP (737 ± 177 mmHg/s vs. 838 ± 199 mmHg/s, P < 0.001) and 26 patients (68%) were defined as acute CRT responders. Patients with premature septal contraction (n = 27) experienced acute improvement in systolic (ΔdP/dtmax: 18.3 ± 8.9%, P < 0.001), diastolic (ΔEDP: -30.6 ± 29.9%, P < 0.001) and electrical (ΔQRS width: -23.3 ± 13.2%, P < 0.001) parameters. No improvement under BIVP was observed in patients (n = 11) with normally timed septal contraction (ΔdP/dtmax: 4.0 ± 7.8%, P = 0.12; ΔEDP: -8.8 ± 38.4%, P = 0.47 and ΔQRS width: -0.9 ± 11.4%, P = 0.79).

CONCLUSION

Septal contraction patterns are an excellent predictor of acute CRT response. Only patients with premature septal contraction experienced acute systolic, diastolic, and electrical improvement under BIVP.

Correlates and Long-Term Implications of Left Ventricular Mechanical Dispersion by Two-Dimensional Speckle-Tracking Echocardiography in Patients with ST-Segment Elevation Myocardial Infarction

BACKGROUND

Left ventricular (LV) mechanical dispersion (LVMD), measured with speckle-tracking echocardiography (STE) after ST-segment elevation myocardial infarction (STEMI), has been proposed as a measurement of regional heterogeneity of myocardial contraction and may reflect changes in the myocardial structure (e.g., fibrosis or edema). Further insight into this parameter may aid in the risk stratification of STEMI patients.

METHODS

A total of 1,000 STEMI patients (77% male, 60 ± 12 years) treated with primary percutaneous coronary intervention were retrospectively analyzed. The LVMD was assessed with two-dimensional STE within 48 hours following the index infarction. Patients were followed for the occurrence of all-cause mortality.

RESULTS

After a median follow-up of 117 months, 229 (23%) patients died. Nonsurvivors showed worse LV ejection fraction (43% ± 10% vs 48% ± 9%; P < .001) and global longitudinal strain (-12.0% ± 3.5% vs -14.2% ± 3.5%; P = .001) and prolonged LVMD (63 [interquartile range, 50-85] msec vs 52 [interquartile range, 42-63] msec; P < .001) compared with survivors. Increasing age, systolic blood pressure, and heart rate at discharge as well as diabetes mellitus, anterior STEMI, TIMI flow < 2, less usage of angiotensin converter enzyme inhibitors or angiotensin receptor blockers, and impaired LV global longitudinal strain were independently associated with more prolonged LVMD. On multivariable analysis, prolonged LVMD was independently associated with increased risk of all-cause mortality (hazard ratio = 1.012; 95% CI, 1.005-1.018; P = .001) and had incremental value for all-cause mortality over clinical and echocardiographic parameters.

CONCLUSIONS

In contemporary STEMI patients, prolonged LVMD was associated with various clinical and echocardiographic parameters. Prolonged LVMD was associated with worse long-term outcome.

Mechanical dispersion in Fabry disease assessed with speckle tracking echocardiography

BACKGROUND

Fabry disease (FD) is a rare X-linked storage disorder caused by deficiency of the lysosomal enzyme α-galactosidase A, and it typically causes multiorgan dysfunction. The main cause of death is heart disease resulting from left ventricular (LV) diastolic dysfunction, LV systolic dysfunction, severe LV hypertrophy (LVH), and sudden death. In several cardiac disorders, LV systolic dysfunction and ventricular arrhythmias are associated with mechanical dispersion (MD). MD has until now not been studied in patients with FD.

OBJECTIVE

To investigate the prevalence of MD in patients with FD.

METHODS

Complete echocardiographic data and speckle tracking echocardiographic data were collected. MD is an index of inter-segmental discoordination of contraction and is defined as the standard deviation (SD) of the time-to-peak longitudinal negative strain in 17 LV segments with a value >49 milliseconds. Patients with FD were divided into the following 2 groups: group I (patients with FD but no LVH, n = 64) and group II (patients with FD and LVH, n = 25). These groups were compared with a group of healthy subjects (group III, n = 50). Parametric variables were expressed as mean ± SD, and nonparametric variables were expressed as median and inter-quartile range. A P value <.05 was considered significant.

RESULTS

A total of 113 patients with FD were included in this study. Of these, 24 (21%) were excluded because of poor imaging quality or presence of comorbidities, and the final study population consisted of 89 patients (mean age of 33.5 ± 14.5 years, 64% female). Group II patients were older than group I patients (46 ± 13 years vs 27 ± 11 years, P < .0001). There was no difference in LV ejection fraction between the 3 groups. There was also no difference in MD between groups I and III (32.4 ms [26-39] vs 32 ms [26-39]). In group II, the MD in 19 patients (76%) was 56 ms (39-80).

CONCLUSIONS

To the best of our knowledge, this is the first study to assess the prevalence of MD in patients with FD. MD was observed in 76% of patients with FD and LVH. The use of MD in strain echocardiography may be beneficial in the assessment of patients with FD who develop heart failure.

Myocardial constructive work and cardiac mortality in resynchronization therapy candidates

BACKGROUND

Recent studies have shown that myocardial constructive work (CW) assessed by pressure-strain loops (PSLs) is an independent predictor of a volumetric response to cardiac resynchronization therapy (CRT). The aim of this study was to evaluate the role of CW in predicting the cardiac outcome of heart failure patients undergoing CRT.

METHODS

This is a retrospective study including 166 CRT candidates (ejection fraction [EF] ≤35%, QRS duration ≥120 milliseconds). Two-dimensional standard echocardiography and speckle-tracking echocardiography were performed before CRT and at 6-month follow-up. PSLs were used to assess myocardial CW.

RESULTS

After a median follow-up of 4 years (range 1.3-5 years), cardiac death occurred in 14 patients (8%). A multivariable Cox regression analysis including age, coronary artery disease, and septal flash showed that CW≤888 mm Hg% was the only independent predictor of cardiac mortality (hazard ratio 4.23, 95% CI 1.08-16.5, P = .03). After 6 months of CRT, a 15% reduction in left ventricular end-systolic volume was observed in 118 (71%) patients, and a CRT volumetric response was identified. Among CRT responders, the concomitant presence of CW ≤888 mm Hg% identified a subgroup of patients at high risk of cardiac death (P = .04 in the log-rank test). The addition of CW ≤888 mm Hg% to a model including age, coronary artery disease, septal flash, and CRT response caused a significant increase in model power for the prediction of cardiac death (χ²: 12.6 vs 25.7, P = .02).

CONCLUSIONS

The estimation of left ventricular CW by PSLs is a relatively novel tool that allows for the prediction of cardiac outcome in CRT candidates.

Global Longitudinal Strain as a Predictor of First and Subsequent Arrhythmic Events in Remotely Monitored ICD Patients With Structural Heart Disease

OBJECTIVES

This study sought to assess speckle-tracking-derived parameters as predictors of first and subsequent ventricular events in patients with structural heart disease and implantable cardioverter-defibrillators (ICD).

BACKGROUND

Left ventricular ejection fraction (LVEF), the current primary parameter of risk stratification for ventricular arrhythmias (VAs) in structural heart diseases is burdened by many limitations.

METHODS

In this retrospective, observational study, all consecutive patients with structural heart disease were admitted for ICD implantation. Patients not followed by a home-monitoring system were excluded. Two-dimensional (2D) speckle-tracking analysis was used to derive global longitudinal strain (GLS), mechanical dispersion (MD), and delta contraction duration (DCD) of all patients at enrollment. Home monitoring was checked weekly to detect all VAs and ICD therapies. A recurrent event statistical approach (Prentice, Williams, and Peterson model) was applied to evaluate subsequent events after the first ones.

RESULTS

A total of 203 patients were consecutively enrolled and followed for a median of 2.2 years. Kaplan-Meier curves showed an increased risk of antitachycardia pacing or shock (log-rank p = 0.003) and VAs (log-rank p = 0.001) associated with lower quartiles of GLS. An impaired GLS was independently associated with an increased risk for the first ICD therapy (hazard ratio [HR]: 1.94; 95% confidence interval [CI]: 1.30 to 2.91; p = 0.001) and (HR: 1.42; 95% CI: 1.01 to 1.98; p = 0.04) for the first VA. GLS impairment was not significantly associated with an increased risk of recurrent ICD therapies or VAs. LVEF, MD, and DCD were not associated with an increased risk of first, second, and third ICD therapies or VA.

CONCLUSIONS

Impaired GLS is associated with an increased risk of VAs and appropriate ICD therapies in a consecutive "real-world," unselected population of remotely monitored patients with structural heart disease, although it does not seem reliable in predicting further arrhythmic events after the first one. MD and DCD do not predict first or subsequent arrhythmic events in ICD patients with structural heart disease.

Myocardial Strain and Dyssynchrony: Incremental Value?

Heart failure (HF) has evolved in an epidemic manner and constitutes a major public health issue. Currently, several prognostic markers and treatment options exist to guide treatment of HF with reduced ejection fraction, but echocardiographic deformation imaging suggests novel pathophysiologic aspects that could help optimize treatment further. Even though no formal treatment options currently exist for patients with HF with preserved ejection fraction, some HF medication does seem to attenuate strain measures. Speckle tracking has furthermore helped characterize this condition and to confer prognostic information. Thus, strain imaging could facilitate novel trials, and thereby hopefully introduce treatment opportunities.

Contractility surrogates derived from three-dimensional lead motion analysis and prediction of acute haemodynamic response to CRT

Background

Patient-specific left ventricular (LV) lead optimisation strategies with immediate feedback on cardiac resynchronisation therapy (CRT) effectiveness are needed. The purpose of this study was to compare contractility surrogates derived from biventricular lead motion analysis to the peak positive time derivative of LV pressure (dP/dt_max) in patients undergoing CRT implantation.

Methods

Twenty-seven patients underwent CRT implantation with continuous haemodynamic monitoring. The right ventricular (RV) lead was placed in apex and a quadripolar LV lead was placed laterally. Biplane fluoroscopy cine films facilitated construction of three-dimensional RV–LV interlead distance waveforms at baseline and under biventricular pacing (BIVP) from which the following contractility surrogates were derived; fractional shortening (FS), time to peak systolic contraction and peak shortening of the interlead distance (negative slope). Acute haemodynamic CRT response was defined as LV ∆dP/dt_max ≥ 10 %.

Results

We observed a mean increase in dP/dt_max under BIVP (899±205 mm Hg/s vs 777±180 mm Hg/s, p<0.001). Based on ΔdP/dt_max, 18 patients were classified as acute CRT responders and nine as non-responders (23.3%±10.6% vs 1.9±5.3%, p<0.001). The baseline RV–LV interlead distance was associated with echocardiographic LV dimensions (end diastole: R=0.61, p=0.001 and end systole: R=0.54, p=0.004). However, none of the contractility surrogates could discriminate between the acute CRT responders and non-responders (ΔFS: −2.5±2.6% vs − 2.0±3.1%, p=0.50; Δtime to peak systolic contraction: −9.7±18.1% vs −10.8±15.1%, p=0.43 and Δpeak negative slope: −8.7±45.9% vs 12.5±54.8 %, p=0.09).

Conclusion

The baseline RV–LV interlead distance was associated with echocardiographic LV dimensions. In CRT recipients, contractility surrogates derived from the RV–LV interlead distance waveform could not discriminate between acute haemodynamic responders and non-responders.

Rational and design of EuroCRT: an international observational study on multi-modality imaging and cardiac resynchronization therapy

Aims

Assessment of left ventricular (LV) volumes and ejection fraction (LVEF) with cardiac imaging is important in the selection of patients for cardiac resynchronization therapy (CRT). Several observational studies have explored the role of imaging-derived LV dyssynchrony parameters to predict the response to CRT, but have yielded inconsistent results, precluding the inclusion of imaging-derived LV dyssynchrony parameters in current guidelines for selection of patients for CRT.

Methods

The EuroCRT is a large European multicentre prospective observational study led by the European Association of Cardiovascular Imaging. We aim to explore if combing the value of cardiac magnetic resonance (CMR) and echocardiography could be beneficial for selecting heart failure patients for CRT in terms of improvement in long-term survival, clinical symptoms, LV function, and volumes. Speckle tracking echocardiography will be used to assess LV dyssynchrony and wasted cardiac work whereas myocardial scar will be assessed with late gadolinium contrast enhanced CMR. All data will be measured in core laboratories. The study will be conducted in European centres with known expertise in both CRT and multimodality cardiac imaging.

Mechanical dispersion is associated with poor outcome in heart failure with a severely depressed left ventricular function and bundle branch blocks

OBJECTIVES

Bundle branch blocks (BBB)-related mechanical dyssynchrony and dispersion may improve patient selection for device therapy, but their effect on the natural history of this patient population is unknown.

METHODS

A total of 155 patients with LVEF ≤ 35% and BBB, not treated with device therapy, were included. Mechanical dyssynchrony was defined as the presence of either septal flash or apical rocking. Contraction duration was assessed as time interval from the electrocardiographic R-(Q-)wave to peak longitudinal strain in each of 17 left ventricular segments. Mechanical dispersion was defined as either the standard deviation of all time intervals (dispersion_SD) or as the difference between the longest and shortest time intervals (dispersion_delta). Patients were followed for cardiac mortality during a median period of 33 months.

RESULTS

Mechanical dyssynchrony was not associated with survival. More pronounced mechanical dispersion_delta was found in patients with dyssynchrony than in those without. In the multivariate regression analysis, patients' functional class, diabetes mellitus and dispersion_delta were independently associated with mortality.

CONCLUSIONS

Mechanical dispersion, but not dyssynchrony, was independently associated with mortality and it may be useful for risk stratification of patients with heart failure (HF) and BBB. Key Messages Mechanical dispersion, measured by strain echocardiography, is associated with poor outcome in heart failure with a severely depressed left ventricular function and bundle branch blocks. Mechanical dispersion may be useful for risk stratification of patients with heart failure and bundle branch blocks.

Multimodality imaging evaluation of Chagas disease: an expert consensus of Brazilian Cardiovascular Imaging Department (DIC) and the European Association of Cardiovascular Imaging (EACVI)

Aims

To develop a document by Brazilian Cardiovascular Imaging Department (DIC) and the European Association of Cardiovascular Imaging (EACVI) to review and summarize the most recent evidences about the non-invasive assessment of patients with Chagas disease, with the intent to set up a framework for standardized cardiovascular imaging to assess cardiovascular morphologic and functional disturbances, as well as to guide the subsequent process of clinical decision-making.

Methods and results

Chagas disease remains one of the most prevalent infectious diseases in Latin America, and has become a health problem in non-endemic countries. Dilated cardiomyopathy is the most severe manifestation of Chagas disease, which causes substantial disability and early mortality in the socially most productive population leading to a significant economical burden. Prompt and correct diagnosis of Chagas disease requires specialized clinical expertise to recognize the unique features of this disease. The appropriate and efficient use of cardiac imaging is pivotal for diagnosing the cardiac involvement in Chagas disease, to stage the disease, assess patients' prognosis and address management. Echocardiography is the most common imaging modality used to assess, and follow-up patients with Chagas disease. The presence of echocardiographic abnormalities is of utmost importance, since it allows to stage patients according to disease progression. In early stages of cardiac involvement, echocardiography may demonstrate segmental left ventricuar wall motion abnormalities, mainly in the basal segments of inferior, inferolateral walls, and the apex, which cannot be attributed to obstructive coronary artery arteries. The prevalence of segmental wall motion abnormalities varies according to the stage of the disease, reaching about 50% in patients with left ventricular dilatation and dysfunction. Speckle tracking echocardiography allows a more precise and quantitative measurement of the regional myocardial function. Since segmental wall motion abnormalities are frequent in Chagas disease, speckle tracking echocardiography may have an important clinical application in these patients, particularly in the indeterminate forms when abnormalities are more subtle. Speckle tracking echocardiography can also quantify the heterogeneity of systolic contraction, which is associated with the risk of arrhythmic events. Three-dimensional (3D) echocardiography is superior to conventional two-dimensional (2D) echocardiography for assessing more accurately the left ventricular apex and thus to detect apical aneurysms and thrombus in patients in whom ventricular foreshortening is suspected by 2D echocardiography. In addition, 3D echocardiography is more accurate than 2D Simpson s biplane rule for assessing left ventricular volumes and function in patients with significant wall motion abnormalities, including aneurysms with distorted ventricular geometry. Contrast echocardiography has the advantage to enhancement of left ventricular endocardial border, allowing for more accurate detection of ventricular aneurysms and thrombus in Chagas disease. Diastolic dysfunction is an important hallmark of Chagas disease even in its early phases. In general, left ventricular diastolic and systolic dysfunction coexist and isolated diastolic dysfunction is uncommon but may be present in patients with the indeterminate form. Right ventricular dysfunction may be detected early in the disease course, but in general, the clinical manifestations occur late at advanced stages of Chagas cardiomyopathy. Several echocardiographic parameters have been used to assess right ventricular function in Chagas disease, including qualitative evaluation, myocardial performance index, tissue Doppler imaging, tricuspid annular plane systolic excursion, and speckle tracking strain. Cardiac magnetic resonance (CMR) is useful to assess global and regional left ventricular function in patients with Chagas diseases. Myocardial fibrosis is a striking feature of Chagas cardiomyopathy and late gadolinium enhancement (LGE) is used to detect and quantify the extension of myocardial fibrosis. Myocardial fibrosis might have a role in risk stratification of patients with Chagas disease. Limited data are available regarding right ventricular function assessed by CMR in Chagas disease. Radionuclide ventriculography is used for global biventricular function assessment in patients with suspected or definite cardiac involvement in Chagas disease with suboptimal acoustic window and contraindication to CMR. Myocardial perfusion scintigraphy may improve risk stratification to define cardiac involvement in Chagas disease, especially in the patients with devices who cannot be submitted to CMR and in the clinical setting of Chagas patients whose main complaint is atypical chest pain. Detection of reversible ischemic defects predicts further deterioration of left ventricular systolic function and helps to avoid unnecessary cardiac catheterization and coronary angiography.

Conclusion

Cardiac imaging is crucial to detect the cardiac involvement in patients with Chagas disease, stage the disease and stratify patient risk and address management. Unfortunately, most patients live in regions with limited access to imaging methods and point-of-care, simplified protocols, could improve the access of these remote populations to important information that could impact in the clinical management of the disease. Therefore, there are many fields for further research in cardiac imaging in Chagas disease. How to better provide an earlier diagnosis of cardiac involvement and improve patients risk stratification remains to be addressed using different images modalities.

Ambulatory blood pressure results and heart rate variability in patients with premature ventricular contractions

BACKGROUND

The presence of premature ventricular contractions (PVCs) is a sign of arrhythmia and typically trigerred by over stimulation of the sympathetic nervous system. This study examined the relationships among PVCs, heart rate variability (HRV), and 24-hour ambulatory blood pressure (ABP) results.

METHODS

This observational clinical study evaluated a cohort of 100 consecutive patients (58 women and 42 men) with PVCs. The individuals were split into occasional (n = 50) and frequent (n = 50) PVCs groups. All Holter recordings were performed during a working day.

RESULTS

Daytime low-frequency power (LFP), daytime low frequency/high frequency (LF/HF), nighttime LFP, and nighttime LF/HF and 24-hour systolic blood pressure (SBP) were slightly higher in the frequent PVCs group (p = 0.046, p = 0.027, p = 0.038, p = 0.032, and p < 0.001, respectively). Hypertension, LF, LF/HF, 24-hour SBP were positively correlated with PVCs (r = 0.305, p = 0.002; r = 0.269, p = 0.007; r = 0.403, p < 0.001, respectively).

CONCLUSION

Frequent PVCs reflect dominance of the sympathetic system according to the results of Holter recordings. This study showed that PVC had a significant association with high blood pressure values. Assessment of ABP and HRV in patients with PVCs is part of a comprehensive approach to the assessment of cardiovascular regulation.

Risk stratification in patients with heart failure: the value of considering both global longitudinal left ventricular strain and mechanical dispersion

In previous studies, mechanical dispersion (MD) predicted ventricular arrhythmias independently of left ventricular ejection fraction (LVEF). Moreover, the combination of MD and global longitudinal strain (GLS) increased the prediction of arrhythmic events. We investigated the prognostic value of a new 2-dimensional strain index, GLS/MD, in patients with heart failure (HF). We analyzed 340 consecutive HF outpatients in sinus rhythm. Echocardiography was performed at 1.6 ± 0.4 months after hospital discharge. The end point included sudden cardiac death, ventricular fibrillation, and sustained ventricular tachycardia (SCD/VA). During the follow-up period (36 ± 9 months), SCD/VA occurred in 48 patients (14.1%). A multivariate Cox regression analysis, which included LVEF, early diastolic transmitral / mitral annular velocity ratio (E/E'), GLS, MD, and GLS/MD in the model, revealed that GLS/MD was the best independent predictor of SCD/VA (HR = 3.22, 95% confidence interval = 1.72-6.15, p = 0.03). Separate inclusion of LVEF, systolic mitral annular velocity, E/E', GLS, and MD together with GLS/MD showed that GLS/MD remained the best predictor of SCD/VA (each p < 0.05). The optimal GLS/MD cutoff value to predict SCA/VA was -0.20%/ms (80% sensitivity, 76% specificity). Irrespective of LVEF, free survival was significantly better in patients with GLS/MD ≤ -0.2%/ms (log-rank test, p < 0.001). In conclusion, GLS/MD may improve cardiovascular risk stratification in subjects with HF.

Strain Imaging Echocardiography: What Imaging Cardiologists Should Know

Despite recent advances in clinical imaging, echocardiography remains as the most accessi-ble and reliable noninvasive. Since knowledge of left ventricular systolic function remains so critically important in determining prognosis; every effort should be made to prevent subjective estimations. The advent of strain imaging echocardiography now offers a readily available and portable imaging tool that not only offers an objective characterization of myocardial dynamics; but also allows for early detection of subclinical left ventricular dysfunction. This review outlines the basic concepts of strain imaging to better understand the mechanism of myocardial function as well their applicability in the least common cardiac diagnosis among current clinical practice.

Myocardial fibrosis predicts ventricular tachyarrhythmias

Myocardial fibrosis is a common pattern in the setting of different heart diseases, and promotes ventricular tachyarrhythmias by creating a vulnerable substrate for reentrant activity and by favoring the emergence of triggers. Currently, late gadolinium enhancement (LGE) cardiac magnetic resonance is considered the reference method for the noninvasive assessment of ventricular fibrosis. Several studies and meta-analyses have shown that ventricular fibrosis detected by LGE is a powerful predictor of ventricular tachyarrhythmic events in ischemic, non-ischemic dilated cardiomyopathy and hypertrophic cardiomyopathy patients. Both the presence and extension of ventricular fibrosis were shown to correlate with the occurrence of ventricular arrhythmias and sudden cardiac death, irrespective of the grade of left ventricular dysfunction. Based on these results, the assessment of ventricular fibrosis has been suggested as a candidate marker to improve the decision making for implantable cardioverter-defibrillator therapy in patients with left ventricular dysfunction. These points will be discussed in the review.

Systolic mitral annulus velocity is a sensitive index for changes in left ventricular systolic function during inotropic therapy in patients with acute heart failure

BACKGROUND

Echocardiography is recommended for assessment of left ventricular systolic function in patients with acute heart failure but few randomised trials have validated techniques like tissue Doppler (TDI) and speckle tracking (STE) in patients with acute heart failure following ST-elevation myocardial infarction.

METHODS

This was a substudy from the LEAF (LEvosimendan in Acute heart Failure following myocardial infarction) trial (NCT00324766 ), which randomised 61 patients developing acute heart failure, including cardiogenic shock, within 48 hours after ST-elevation myocardial infarction, double-blind to a 25-hour infusion of levosimendan or placebo. TDI-derived systolic mitral annulus velocity (S'), STE-derived global longitudinal strain (S_l) and strain rate (SR_l) were measured at baseline, day 1, day 5 and after 42 days.

RESULTS

Datasets rejected for analyses were 2% (TDI) and 17% (STE). S' increased by 23% in the levosimendan group versus 8% in the placebo group from baseline to day 1 ( p= 0.011) and by 30% vs. 3% from baseline to day 5 ( p <0.0005). Significant, but less pronounced, improvements in global S_l ( p = 0.025 and p = 0.032) and in global SR_l ( p = 0.046 and p = 0.001) in favour of levosimendan were also present.

CONCLUSION

S' by TDI and STE-derived S_l and SR_l were sensitive indices for changes in left ventricular systolic function related to treatment with levosimendan. However, S' by TDI was more feasible and sensitive and might be preferred for assessment of changes in left ventricular systolic function in critically ill patients with acute heart failure receiving inotropic therapy.

Coupling of ventricular action potential duration and local strain patterns during reverse remodeling in responders and nonresponders to cardiac resynchronization therapy

BACKGROUND

The high risk of ventricular arrhythmias in patients with heart failure remains despite the benefit of cardiac resynchronization therapy (CRT). An electromechanical interaction between regional myocardial strain patterns and the electrophysiological substrate is thought to be important.

OBJECTIVE

We investigated the in vivo relation between left ventricular activation recovery interval (ARI), as a surrogate measure of action potential duration (APD), and local myocardial strain patterns in responders and nonresponders to CRT.

METHODS

ARIs were recorded from the left ventricular epicardium in 20 patients with CRT 6 weeks and 6 months post implantation. Two-dimensional speckle tracking echocardiography was performed at the same time to assess myocardial strains. Patients with ≥15% reduction in end-systolic volume at 6 months were classified as responders.

RESULTS

ARI decreased in responders (263 ± 46 ms vs 246 ± 47 ms, P < .01) and increased in nonresponders (235 ± 23 ms vs 261 ± 20 ms; P < .01). Time-to-peak radial, circumferential, and longitudinal strains increased in responders (41 ± 27, 35 ± 25, 56 ± 37 ms; P < .01) and decreased in nonresponders (-58 ± 26, -47 ± 26, -64 ± 27 ms; P < .01). There was a nonlinear correlation between changes in time-to-peak strain and ARIs (Spearman correlation coefficient r ≥ 0.70; P < .01). Baseline QRS duration >145 ms and QRS duration shortening with biventricular pacing were associated with ARI shortening following CRT.

CONCLUSION

Changes in ventricular wall mechanics predict local APD lengthening or shortening during CRT. Nonresponders have a worsening of myocardial strain and local APD. Baseline QRS duration >145 ms and QRS duration shortening with biventricular pacing identified patients who exhibited improvement in APD.

Additive Prognostic Value of Echocardiographic Global Longitudinal and Global Circumferential Strain to Electrocardiographic Criteria in Patients With Heart Failure Undergoing Cardiac Resynchronization Therapy

Background—

Response to cardiac resynchronization therapy is most favorable in patients with heart failure with QRS duration ≥150 ms and left bundle branch block and less predictable in those with QRS width 120 to 149 ms or non–left bundle branch block.

Methods and Results—

We studied 205 patients with heart failure referred for cardiac resynchronization therapy with QRS ≥120 ms and ejection fraction ≤35%. We tested the hypothesis that contractile function using speckle-tracking echocardiographic global circumferential strain (GCS) from 2 short-axis views and global longitudinal strain (GLS) from 3 apical views add prognostic value to electrocardiographic criteria. There were 112 patients (55%) with GLS >−9% and 136 patients (66%) with GCS >−9%. During 4 years, 81 patients reached the combined primary end point (death, circulatory support, or transplant) and 120 reached the secondary end point (heart failure hospitalization or death). Both GLS >−9% and GCS >−9% were associated with increased risk of unfavorable events as follows: for the primary end point (hazard ratio=2.91; 95% confidence interval, 1.88–4.49; P <0.001) and (hazard ratio=3.73; 95% confidence interval, 2.39–5.82; P <0.001) for the secondary end point (hazard ratio=2.10; 95% confidence interval, 1.45–3.05; P <0.001) and (hazard ratio=3.25; 95% confidence interval, 2.23–4.75; P <0.001). In a prespecified subgroup of 120 patients with QRS 120 to 149 ms or non–left bundle branch block, significant associations of baseline GLS and GCS and outcomes remained: P =0.014 and P =0.002 for the primary end point and P =0.049 and P =0.001 for the secondary end point. Global strain measures had additive prognostic value to routine clinical or electrocardiographic parameters ( P <0.001).

Conclusions—

Baseline GCS and GLS were significantly associated with long-term outcome after cardiac resynchronization therapy and had additive prognostic value to routine clinical and electrocardiographic selection criteria for cardiac resynchronization therapy.

Strain-time curve analysis by speckle tracking echocardiography in cardiac resynchronization therapy: Insight into the pathophysiology of responders vs. non-responders

Background

Patients with non-ischemic heart failure etiology and left bundle branch block (LBBB) show better response to cardiac resynchronization therapy (CRT). While these patients have the most pronounced left ventricular (LV) dyssynchrony, LV dyssynchrony assessment often fails to predict outcome. We hypothesized that patients with favorable outcome from CRT can be identified by a characteristic strain distribution pattern.

Methods

From 313 patients who underwent CRT between 2003 and 2006, we identified 10 patients who were CRT non-responders (no LV end-systolic volume [LVESV] reduction) with non-ischemic cardiomyopathy and LBBB and compared with randomly selected CRT responders (n = 10; LVESV reduction ≥15 %). Longitudinal strain (ε_long) data were obtained by speckle tracking echocardiography before and after (9 ± 5 months) CRT implantation and standardized segmental ε_long-time curves were obtained by averaging individual patients.

Results

In responders, ejection fraction (EF) increased from 25 ± 9 to 40 ± 11 % (p = 0.002), while in non-responders, EF was unchanged (20 ± 8 to 21 ± 5 %, p = 0.57). Global ε_long was significantly lower in non-responders at pre CRT (p = 0.02) and only improved in responders (p = 0.04) after CRT. Pre CRT septal ε_long -time curves in both groups showed early septal contraction with mid-systolic decrease, while lateral ε_long showed early stretch followed by vigorous mid to late contraction. Restoration of contraction synchrony was observed in both groups, though non-responder remained low amplitude of ε_long.

Conclusions

CRT non-responders with LBBB and non-ischemic etiology showed a similar improvement of ε_long pattern with responders after CRT implantation, while amplitude of ε_long remained unchanged. Lower ε_long in the non-responders may account for their poor response to CRT.