The relationship between time from myocardial infarction, left ventricular dyssynchrony, and the risk for ventricular arrhythmia: speckle-tracking echocardiographic analysis

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.

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.

Association of Pro-B-Type Natriuretic Peptide With Cardiac Magnetic Resonance-Measured Global and Regional Cardiac Function and Structure Over 10 Years: The MESA Study

Background NT-proBNP (N-terminal pro-B-type natriuretic peptide) is widely used to diagnose and manage patients with heart failure. We aimed to investigate associations between NT-proBNP levels and development of global and regional myocardial impairment, dyssynchrony, and risk of developing myocardial scar over time. Methods and Results We included 2416 adults (45-84 years) without baseline clinical cardiovascular disease from MESA (Multi-Ethnic Study of Atherosclerosis). NT-proBNP was assessed at baseline (2000-2002). Cardiac magnetic resonance-measured left ventricular parameters were assessed at baseline and year 10 (2010-2012). Tagged cardiac magnetic resonance and myocardial dyssynchrony were assessed. We used linear and logistic regression models to study the relationships between quartiles of NT-proBNP levels and outcome variables. Left ventricular parameters decreased over time. After 10-year follow-up and adjusting for cardiovascular disease risk factors, people in the highest quartile had significantly greater decline in left ventricular ejection fraction (-1.60%; 95% CI, -2.26 to -0.94; P<0.01) and smaller decline in left ventricular end systolic volume index (-0.47 mL/m2; 95% CI, -1.18 to 0.23; P<0.01) compared with those in the lowest quartile. Individuals in the highest quartile had more severe risk factor adjusted global, mid, and apical regional dyssynchrony compared with those in the lowest, second, and third quartiles (all P-trend<0.05). Compared with the lowest-quartile group, the adjusted odds ratios for having myocardial scar was 1.3 (95% CI, 0.7-2.2) for quartile 2; 1.2 (95% CI, 0.6-2.3) for quartile 3; and 2.7 (95% CI, 1.4-5.5) for quartile 4 (P-trend=0.012) for the total sample. Conclusions Among participants without baseline clinical cardiovascular disease, higher baseline NT-proBNP concentration was significantly associated with subclinical changes in developing myocardial dysfunction, more severe cardiac dyssynchrony, and higher odds of having myocardial scar over a 10-year period independent of traditional cardiovascular disease risk factors.

Layer-specific strain and dyssynchrony index alteration in new-onset systemic lupus erythematosus patients without cardiac symptoms

Background

Layer-specific speckle-tracking echocardiography (STE) is a noninvasive approach that assesses subclinical left ventricular dysfunction. We aimed to investigate the (I) alteration of layer-specific STE parameters and the dyssynchrony index; and (II) the disease parameters associated with layer-specific STE change in drug-naïve patients with new-onset systemic lupus erythematosus (SLE) without cardiac symptoms.

Methods

Thirty-five drug-naïve patients with new-onset SLE and twenty-five healthy controls were enrolled. All individuals received both conventional echocardiographic and two-dimensional STE assessment. The data of layer-specific global longitudinal strain (GLS), global circumferential strain (GCS), and peak systolic dispersion (PSD) were acquired in layer-specific STE.

Results

All patients had a normal left ventricular ejection fraction (LVEF)(mean LVEF: 58%) and conventional echocardiographic parameters were comparable between patients and controls. Decreased layer-specific GLS and elevated PSD were observed in SLE patients (whole layer GLS: -17.6%±3.0% versus -19.3%±2.6%, P=0.02; endocardial GLS: -20.0%±3.2% versus -22.1%±3.0%, P=0.01; epicardial GLS: -15.6%±2.7% versus -16.8%±2.4%, P=0.04; PSD: 41.0±18.9 versus 28.8±10.1 msec, P=0.007). In contrast, there was no difference in layer-specific GCS at three different levels between patients and controls (P>0.05). More severely impaired GLS was observed in patients with higher disease activity, high-risk antiphospholipid antibody (aPL) profile, or renal involvement. The PSD was increased in patients with higher disease activity or a high-risk aPL profile. Correlational analysis showed that GLS at three layers and PSD correlated with high-sensitivity C-reactive protein (hsCRP) levels (whole GLS: r=0.662, P<0.001; endocardial GLS: r=0.637, P<0.001; epicardial GLS: r=0.658, P<0.001; PSD: r=0.390, P=0.021). PSD correlated with epicardial GLS (r=0.360, P=0.047), when treating the hsCRP level, renal involvement, aPL profile, and disease activity as control variables. Multivariate regression showed the hsCRP level and epicardial GLS were predictors of layer-specific GLS impairment and elevated PSD, respectively.

Conclusions

Drug-naive patients with new-onset SLE are likely to have subclinical GLS impairment and left ventricular dyssynchrony, even in the presence of normal LVEF. SLE-related risk factors are associated with these dysfunctions.

Multimodality imaging predictors of sudden cardiac death

Sudden cardiac death (SCD) is the worst clinical event occurring in the clinical context of cardiomyopathies. Current guidelines recommend using LV ejection fraction as the only imaging-derived parameter to identify patients who may benefit from ICD implantation in cardiomyopathies with reduced ejection fraction; however, a relevant proportion of high-risk population is left with unmet therapeutic goal. In case of dilated, hypertrophic, or arrhythmogenic cardiomyopathies, there is still a room for more sensitive and specific risk markers for identifying a cluster at higher risk of SCD. In this paper, we reviewed the evidence supporting the use of advanced echocardiography, CMR, and nuclear cardiology for SCD stratification in patients with the most common cardiomyopathies. The added value of these modalities may be explained on the basis of tissue characterization, especially scar detection, a central player in the pathogenesis of arrhythmias. Therefore, integration of these modalities to our everyday clinical practice may help in dealing with the gray zones where current guidelines are still ineffective for patient selection.

Resting Left Ventricular Dyssynchrony and Mechanical Reserve in Asymptomatic Normotensive Subjects with Early Type 2 Diabetes Mellitus

Background

Most diabetic patients have silent ischemia and cardiac dysfunction that is usually observed in the late phase of the disease when it becomes clinically obvious. We hypothesized that left ventricular dyssynchrony (LVdys) (or dispersion) is an early marker of myocardial involvement in asymptomatic early type 2 diabetes mellitus (T2DM) patients. Therefore, we aimed to detect early markers of myocardial dysfunction in early T2DM using LVdys and left ventricular mechanical reserve (LVMR).

Methods

We examined 91 consecutive subjects with early T2DM with speckle tracking imaging to evaluate LVdys and with dobutamine stress to evaluate LVMR (defined as left ventricular mechanical reserve global longitudinal strain [LVMR_GLS] ≥2%). Our patients were divided into two groups according to LVdys: group 1 with LVdys (n = 49), and group 2 without LVdys (n = 42).

Results

We found that 49 (54%) subjects in our cohort had resting LVdys (standard deviation of tissue synchronization of the 12 left ventricular segments [Ts-SD-12] ≥34.2 ms). GLS and strain rate were comparable at rest between patients with and without LVdys. On the other hand, LVMR was blunted in those with LVdys (p < 0.001). We found that HbA1c, high-sensitivity C-reactive protein, and left atrial volume index were inversely correlated with LVMR. Multivariate analysis showed that LVdys was the strongest predictor (p < 0.001) of blunted LVMR. Using receiver operating characteristic curve analysis, we found that a Ts-SD-12 ≥36.5 ms was the best cutoff value to predict blunted LVMR (area under the curve = 0.89, p < 0.001).

Conclusion

The LVdys (Ts-SD-12) cutoff ≥36.5 ms was the optimal value for prediction of impaired LVMR and might be an early marker of subclinical cardiac dysfunction and risk stratification of subjects with asymptomatic early T2DM with preserved left ventricular ejection fraction.

Correlation Between T Peak to End Interval and Left Ventricular Time to Peak Longitudinal Strain in Ischemic Cardiomyopathy Patients

Background

Ischemic cardiomyopathy is the most frequent etiology of heart failure with reduced ejection fraction (HFrEF) and a result of ventricular structural, functional and electrical remodeling. T peak to end (Tpe) interval is an electrocardiographic parameter that represents repolarization heterogeneity and had prognostic value for ventricular arrhythmia. Patients with ischemic cardiomyopathy face a significant burden of arrhythmias. Mechanical dispersion is a functional remodeling parameter that can be measured by time to peak longitudinal strain using speckle tracking echocardiography. This study aimed to assess the relationship between Tpe interval with time to peak longitudinal strain in ischemic cardiomyopathy patients.

Methods

This study was conducted with an observational analytical cross-sectional design. Ischemic cardiomyopathy subjects were included at Dr. Hasan Sadikin General Hospital, Bandung, from August to October 2019. Tpe interval was measured manually with the tangential method. Time to peak longitudinal strain was measured using speckle tracking echocardiography. The correlation between Tpe interval and time to peak longitudinal strain was analyzed using Pearson correlation.

Results

A total of 30 subjects were included in this study. The average age was 58 ± 8 years old, and the average left ventricular ejection fraction was 27±5.5%. The average of Tpe interval was 83.4 ± 7.62 ms, and the average time to peak longitudinal strain was 93.13 ± 34.51 ms. The Pearson correlation test showed a significant weak positive correlation (r = 0.386, 95% confidence interval: 0.029 - 0.743, P = 0.018) between Tpe interval and time to peak longitudinal strain in ischemic cardiomyopathy patients.

Conlucions

There was a significant weak positive correlation between Tpe interval and time to peak longitudinal strain in ischemic cardiomyopathy patients.

Structural and Physiological Imaging to Predict the Risk of Lethal Ventricular Arrhythmias and Sudden Death

Identifying patients at risk of sudden cardiac death remains a major challenge in cardiovascular medicine. Advances in cardiovascular imaging have identified several anatomic and functional variables that can be quantified as continuous variables to predict the risk of developing lethal ventricular tachyarrhythmias in patients with depressed left ventricular (LV) systolic function. Some, such as LV mass, volume, and the dyssynchrony of contraction, can be derived from currently available echocardiographic and nuclear imaging modalities. Others require advanced cardiac imaging modalities with quantification of myocardial scar with gadolinium-enhanced cardiac magnetic resonance and myocardial sympathetic denervation using norepinephrine analogs and positron emission tomography or single-photon emission computed tomography offering the most promise. There is an immediate need to develop a sequential cost-effective approach that capitalizes on readily available clinical information complemented with advanced imaging modalities in selected patients to improve risk stratification for arrhythmic death beyond LV ejection fraction.

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.

Imaging for sudden cardiac death risk stratification: Current perspective and future directions

Sudden cardiac death (SCD) accounts for one fifth of global deaths, and occurs when a trigger (e.g. myocardial ischemia, premature ventricular contraction) interacts with an arrhythmic substrate (e.g. myocardial scar, dilated cardiomyopathy). Multimodality imaging (echocardiographic, cardiac magnetic resonance and nuclear techniques) can potentially visualize many predisposing substrates and triggers. Implantable cardioverter-defibrillator (ICD) is the most effective approach to primary prevention of SCD, and current guidelines regarding ICD implantation are based on a left ventricular ejection fraction (LVEF) ≤35%. This practice is limited by a low sensitivity and specificity, and has limited value when applied to different etiologies. In this review, the role of multimodality imaging in SCD risk-stratification and the limitations of an LVEF-based approach, are discussed. Additional randomized, prospective data are eagerly awaited to inform on the role of imaging in SCD risk-stratification, and ongoing/ planned trials are subsequently discussed.

Prognostic importance of mechanical dyssynchrony in predicting heart failure development after ST-segment elevation myocardial infarction

The aim of this study is to assess the prognostic value of mechanical dyssynchrony defined as the standard deviation of the time to peak longitudinal strain (SD T2P LS) in predicting the development of heart failure (HF) after an ST-segment elevation myocardial infarction (STEMI). Three hundred and seventy-three patients were admitted with STEMI and treated with primary percutaneous coronary intervention. Left ventricular (LV) mechanical dyssynchrony was examined through speckle tracking echocardiography and defined as SD T2P LS. The association with the outcome of HF hospitalization was assessed using Cox proportional hazard models. During a median follow-up of 5.12 years, 144 patients (38.6%) were admitted due to HF. Worse dyssynchrony was associated with the outcome in unadjusted and multivariable analysis (multivariable hazard ratio 1.05, 95% confidence interval 1.00-1.10, p-value 0.039, per 10 ms increase), but not after further adjustment for LV ejection fraction (LVEF), E/e' and global longitudinal strain (GLS) (hazard ratio 1.01, 95% confidence interval 1.00-1.07, p-value 0.71, per 10 ms increase), nor in a model only adjusting for GLS (hazard ratio 1.01, 95% confidence interval 1.00-1.06, p-value 0.61, per 10 ms increase). These findings were reproduced in a competing risk analysis treating all-cause mortality as a competing risk. LV mechanical dyssynchrony, as assessed by SD T2P LS is not an independent predictor of post-STEMI HF development and mechanical dyssynchrony does not provide independent prognostic information regarding HF when GLS is known.

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.

Left ventricular diastolic and systolic dyssynchrony and dysfunction in heart failure with preserved ejection fraction and a narrow QRS complex

Aims: Mechanical dyssynchrony has been reported in heart failure with preserved ejection fraction (HFpEF), with a majority of patients having a narrow QRS complex; however, whether any benefit is observed with restoration of dyssynchrony remains unclear. We sought to assess left ventricular (LV) dyssynchrony and function in HFpEF and elucidate the underlying mechanisms that may account for HFpEF. Methods: Seventy-eighty patients with a narrow QRS complex including 47 with HFpEF, 31 with heart failure with reduced ejection fraction (HFrEF) patients, and 29 with asymptomatic left ventricular diastolic dysfunction (LVDD) were recruited. Forty-five normal subjects acted as controls. Systolic LV longitudinal strain (LS), systolic longitudinal strain rate (LSrS), early diastolic longitudinal strain rate (LSrE), and late diastolic longitudinal strain rate (LSrA) were measured using speckle tracking echocardiography. LV diastolic and systolic dyssynchrony (Te-SD and Ts-SD) were calculated. Results: Te-SD and Ts-SD were prolonged in HFpEF and HFrEF patients than in the control group (p<0.05). However, Ts-SD was shorter in HFpEF patients compared to HFrEF patients despite a narrow QRS complex (p<0.05). LV global LS, LSrS, and LSrE were decreased in patients with HFpEF and HFrEF compared to other groups, with HFrEF being even more reduced than HFpEF (p<0.05). Reduced LS, LSrS, and LSrE could effectively differentiate HF from asymptomatic LVDD patients (p<0.05). Conclusion: HFrEF exhibited increased systolic dyssynchrony compared to HFpEF despite a narrow QRS complex in addition to the more reduced diastolic and systolic function. Therefore, targeting to improve diastolic and systolic function instead of managing systolic dyssynchrony might be of great importance in the treatment of HFpEF.

Regional Longitudinal Deformation Improves Prediction of Ventricular Tachyarrhythmias in Patients With Heart Failure With Reduced Ejection Fraction

Background—

Left ventricular dysfunction is a known predictor of ventricular arrhythmias. We hypothesized that measures of regional longitudinal deformation by speckle-tracking echocardiography predict ventricular tachyarrhythmias and provide incremental prognostic information over clinical and conventional echocardiographic characteristics.

Methods and Results—

We studied 1064 patients enrolled in the MADIT-CRT trial (Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy) with speckle-tracking data available. Peak longitudinal strain was obtained for the septal, lateral, anterior, and inferior myocardial walls at baseline. The end point was the first event of ventricular tachycardia (VT) or fibrillation (VF). During the median follow-up of 2.9 years, 254 (24%) patients developed VT/VF. Patients with VT/VF had significantly lower left ventricular ejection fraction (28.3% versus 29.5%; P <0.001) and longitudinal strain in all myocardial walls compared with patients without VT/VF (anterior-strain, −7.7% versus −8.8%; P <0.001; lateral-strain, −7.3% versus −7.9%; P =0.022; inferior-strain, −8.3% versus −9.9%; P <0.001; septal-strain, −9.1% versus −10.0%; P <0.001). After multivariate adjustment, only anterior and inferior longitudinal strain remained independent predictors of VT/VF (anterior: hazard ratio, 1.08 [1.03–1.13]; P =0.001; inferior: hazard ratio, 1.08 [1.04–1.12]; P <0.001; per 1% absolute decrease for both). When including B-type natriuretic peptide in the model, only a decreasing myocardial function in the inferior myocardial wall predicted VT/VF (hazard ratio, 1.05 [1.00–1.11]; P =0.039). Only strain obtained from the inferior myocardial wall provided incremental prognostic information for VT/VF over clinical and echocardiographic parameters (C statistic 0.71 versus 0.69; P =0.005).

Conclusions—

Assessment of regional longitudinal myocardial deformation in the inferior region provided incremental prognostic information over clinical and echocardiographic risk factors in predicting ventricular tachyarrhythmias.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00180271.

Diagnostic and prognostic roles of echocardiography and cardiac magnetic resonance

Accurate prediction of sudden cardiac death due to ventricular arrhythmia remains challenging. Left ventricular ejection fraction has shown an association with increased risk of ventricular arrhythmias and is included in the recommendations for implantable cardioverter defibrillator as primary prevention. However, left ventricular ejection fraction may be normal in a large number of patients who are at risk of ventricular arrhythmias. Echocardiography remains the imaging technique of first choice to rule out the presence of structural heart disease and assess left and right ventricular function. Advances in strain echocardiography and cardiac magnetic resonance have provided important insights into the mechanisms of ventricular arrhythmias, and will be summarized in this review.

Imaging for assessment of sudden death risk: current role and future prospects

Sudden cardiac death (SCD) remains a major public health problem and there is an urgent need to maximize the impact of primary prevention using the implantable defibrillator. While implantable defibrillators are of utility for prevention of SCD, current methods of selecting candidates have significant shortcomings. Major advancements have occurred in the field of cardiac imaging, with significant potential to identify novel cardiac substrates for improved prediction. While assessment of the left ventricular ejection fraction remains the current major predictor, it is likely that several novel imaging markers will be incorporated into future risk stratification approaches. The goal of this review is to discuss the current status and future potential of cardiac imaging modalities to enhance risk stratification for SCD.

Mechanical Dyssynchrony by Tissue Doppler Cross-Correlation is Associated with Risk for Complex Ventricular Arrhythmias after Cardiac Resynchronization Therapy

BACKGROUND

Tissue Doppler cross-correlation analysis has been shown to be associated with long-term survival after cardiac resynchronization defibrillator therapy (CRT-D). Its association with ventricular arrhythmia (VA) is unknown.

METHODS

From two centers 151 CRT-D patients (New York Heart Association functional classes II-IV, ejection fraction ≤ 35%, and QRS duration ≥ 120 msec) were prospectively included. Tissue Doppler cross-correlation analysis of myocardial acceleration curves from the basal segments in the apical views both at baseline and 6 months after CRT-D implantation was performed. Patients were divided into four subgroups on the basis of dyssynchrony at baseline and follow-up after CRT-D. Outcome events were predefined as appropriate antitachycardia pacing, shock, or death over 2 years.

RESULTS

Mechanical dyssynchrony was present in 97 patients (64%) at baseline. At follow-up, 42 of these 97 patients (43%) had persistent dyssynchrony. Furthermore, among 54 patients with no dyssynchrony at baseline, 15 (28%) had onset of new dyssynchrony after CRT-D. In comparison with the group with reduced dyssynchrony, patients with persistent dyssynchrony after CRT-D were associated with a substantially increased risk for VA (hazard ratio [HR], 4.4; 95% CI, 1.2-16.3; P = .03) and VA or death (HR, 4.0; 95% CI, 1.7-9.6; P = .002) after adjusting for other covariates. Similarly, patients with new dyssynchrony had increased risk for VA (HR, 10.6; 95% CI, 2.8-40.4; P = .001) and VA or death (HR, 5.0; 95% CI, 1.8-13.5; P = .002).

CONCLUSIONS

Persistent and new mechanical dyssynchrony after CRT-D was associated with subsequent complex VA. Dyssynchrony after CRT-D is a marker of poor prognosis.

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

Aims

Cardiac resynchronization therapy (CRT) reduces morbidity and mortality in heart failure. However, prediction of the outcome remains difficult. We aimed to investigate for echocardiographic predictors of ventricular arrhythmias and fatal outcome and to explore how myocardial function is changed by biventricular pacing in heart failure.

Methods and results

We prospectively included 170 heart failure patients (66 ± 10 years, New York Heart Association class 2.8 ± 0.5, 48% ischaemic cardiomyopathy) and recorded ventricular arrhythmias and fatal end point defined as death, heart transplantation, or left ventricular assist device implantation during 2 years. Two-dimensional echocardiography was performed before and 6 months after CRT implantation. CRT response was defined as ≥15% reduction in end-systolic volume at 6 months. Speckle-tracking technique was performed to assess longitudinal and circumferential left ventricular function, defined as global longitudinal (GLS) and circumferential strain (GCS), and to assess mechanical dyssynchrony, defined as mechanical dispersion. GLS before CRT was a predictor of fatal end point independently of CRT response [hazard ratio, HR 1.14 (1.02–1.27), P = 0.02]. Patients with GLS better than −8.3% showed event-free survival benefit (log rank, P < 0.001). Mechanical dispersion at 6 months was an independent predictor of ventricular arrhythmias [HR 1.20 (1.06–1.35), P = 0.005]. CRT responders (59%) had improvement of both GLS and GCS.

Conclusion

In heart failure patients with CRT, worse longitudinal function before CRT was an important predictor of fatal outcome during 2 years, independently of CRT response. Mechanical dispersion at 6 months was a strong predictor of ventricular arrhythmias. CRT response by reverse remodelling was dependent on improvement of both longitudinal and circumferential function.