Left Ventricular Mechanical Dispersion Research Articles

Association of cardiovascular magnetic resonance-derived circumferential strain parameters with the risk of ventricular arrhythmia and all-cause mortality in patients with prior myocardial infarction and primary prevention implantable cardioverter defibrillator

BackgroundImpaired left ventricular (LV) contraction and relaxation may further promote adverse remodeling and may increase the risk of ventricular arrhythmia (VA) in ischemic cardiomyopathy. We aimed to examine the association of cardiovascular magnetic resonance (CMR)-derived circumferential strain parameters for LV regional systolic function, LV diastolic function and mechanical dispersion with the risk of VA in patients with prior myocardial infarction and primary prevention implantable cardioverter defibrillator (ICD).MethodsPatients with an ischemic cardiomyopathy who underwent CMR prior to primary prevention ICD implantation, were retrospectively identified. LV segmental circumferential strain curves were extracted from short-axis cine CMR. For LV regional strain analysis, the extent of moderately and severely impaired strain (percentage of LV segments with strain between − 10% and − 5% and > − 5%, respectively) were calculated. LV diastolic function was quantified by the early and late diastolic strain rate. Mechanical dispersion was defined as the standard deviation in delay time between each strain curve and the patient-specific reference curve. Cox proportional hazard ratios (HR) (95%CI) were calculated to assess the association between LV strain parameters and appropriate ICD therapy.ResultsA total of 121 patients (63 ± 11 years, 84% men, LV ejection fraction (LVEF) 27 ± 9%) were included. During a median (interquartile range) follow-up of 47 (27;69) months, 30 (25%) patients received appropriate ICD therapy. The late diastolic strain rate (HR 1.1 (1.0;1.2) per − 0.25 1/s, P = 0.043) and the extent of moderately impaired strain (HR 1.5 (1.0;2.2) per + 10%, P = 0.048) but not the extent of severely impaired strain (HR 0.9 (0.6;1.4) per + 10%, P = 0.685) were associated with appropriate ICD therapy, independent of LVEF, late gadolinium enhancement (LGE) scar border size and acute revascularization. Mechanical dispersion was not related to appropriate ICD therapy (HR 1.1 (0.8;1.6) per + 25 ms, P = 0.464).ConclusionsIn an ischemic cardiomyopathy population referred for primary prevention ICD implantation, the extent of moderately impaired strain and late diastolic strain rate were associated with the risk of appropriate ICD therapy, independent of LVEF, scar border size and acute revascularization. These findings suggest that disturbed LV contraction and relaxation may contribute to an increased risk of VA after myocardial infarction.

Prediction of Life-Threatening Ventricular Arrhythmia in Patients With Arrhythmogenic Cardiomyopathy: A Primary Prevention Cohort Study

ObjectivesThis study aimed to identify clinical, electrocardiographic (ECG) and cardiac imaging predictors of first-time life-threatening ventricular arrhythmia in patients with arrhythmogenic cardiomyopathy (AC). BackgroundThe role of clinical, electrocardiographic, and cardiac imaging parameters in risk stratification of patients without ventricular arrhythmia is unclear. MethodsWe followed consecutive AC probands and mutation-positive family members with no documented ventricular arrhythmia from time of diagnosis to first event. We assessed clinical, electrocardiographic, and cardiac imaging parameters according to Task Force Criteria of 2010 in addition to left ventricular (LV) and strain parameters. High-intensity exercise was defined as >6 metabolic equivalents. ResultsWe included 117 patients (29% probands, 50% female, age 40 ± 17 years). During 4.2 (interquartile range [IQR]: 2.4 to 7.4) years of follow-up, 18 (15%) patients experienced life-threatening ventricular arrhythmias. The 1-, 2-, and 5-year incidence was 6%, 9%, and 22%, respectively. History of high-intensity exercise, T-wave inversions ≥V3, and greater LV mechanical dispersion were the strongest risk markers (adjusted hazard ratio [HR]: 4.7 [95% confidence interval (CI): 1.2 to 17.5]; p = 0.02, 4.7 [95% CI: 1.6 to 13.9]; p = 0.005), and 1.4 [95% CI: 1.2 to 1.6] by 10-ms increments; p < 0.001, respectively). Median arrhythmia-free survival in patients with all risk factors was 1.2 (95% CI: 0.4 to 1.9) years, compared with an estimated 12.0 (95% CI: 11.5 to 12.5) years in patients without any risk factors. ConclusionsHistory of high-intensity exercise, electrocardiographic T-wave inversions ≥V3, and greater LV mechanical dispersion were strong predictors of life-threatening ventricular arrhythmia. Patients without any of these risk factors had minimal risk, whereas ≥2 risk factors increased the risk dramatically. This may help to make decisions on primary preventive implantable cardioverter defibrillator (ICD) therapy.

Reduced left ventricular mechanical dispersion at 6 months follow-up after cardiac resynchronization therapy is associated with superior long-term outcome

In heart failure (HF) patients, left ventricular mechanical dispersion (LVMD) reflects heterogeneous mechanical activation of the left ventricle. In HF patients, LVMD can be reduced after CRT. Whether lesser LVMD is associated with improved outcome is unknown. The purpose of this study was to relate LVMD to long-term prognosis in a large cohort of HF patients after 6 months of cardiac resynchronization therapy (CRT). Clinical, echocardiographic, and ventricular arrhythmia (VA) data were analyzed from an ongoing registry of HF recipients of CRT. Baseline (before CRT) and 6-month echocardiograms were evaluated. LVMD was calculated as the standard deviation of the time from onset of the QRS complex to the peak longitudinal strain in a 17-segment model. Patients were divided into 2groupsaccording to the median LVMD (84 ms) at 6 months post-CRT. Of 1185 patients (mean age 65 ± 10 years; 76% male), 343 (29%) died during a mean follow-up of 55 ± 36 months. Baseline LVMD was not associated with all-cause mortality and VA at follow-up. In contrast, patients with less LVMD (≤84 ms) at 6 months post-CRT had lower event rates (VA and mortality) compared to those with LVMD >84 ms. On multivariable analysis, greater LVMD at 6 months after CRT was independently associated with an increased risk of mortality (hazard ratio 1.002; P = .037) and VA (hazard ratio 1.003; P = .026). Larger LVMD at 6 months after CRT is independently associated with all-cause mortality and VA. LVMD may be valuable in identifying patients who remain at high mortality risk after CRT implantation.

The impact of overt hypothyroidism on left ventricular mechanical synchrony: speckle tracking echocardiography study

Objective To explore the impact of hypothyroidism on left ventricular (LV) mechanics using two-dimensional speckle tracking imaging (2D-STI). Methods Forty-two patients with newly diagnosed overt hypothyroidism (HT) were prospectively collected as the case group and 47 subjects matching by age, gender and hypertension history were enrolled as control group. All participants received comprehensive echocardiography examination, and 2D-STI was used to assess LV global longitudinal strain (GLS) and mechanical dispersion (MD). The inter-group difference in GLS and MD, correlations with thyroid hormones and reproducibility were evaluated. Results LV GLS at both sectional (apical 4-, 3-, 2-chamber views) and global levels were significantly impaired in the HT group than the control group[(-21.3±3.2)% vs (-23.9±2.9)%, (-20.4±3.8)% vs (-22.7±2.9)%, (-21.2±3.9)% vs (-23.9±2.5)%, (-20.9±3.4)% vs (-23.5±2.3)%; all P<0.01]. Similarly, MD at both sectional (apical 4-, 3-, 2-chamber views) and global levels were significantly prolonged in the HT group than the control group[3.4 ms vs 0.9 ms, 2.2 ms vs 0.7 ms, 2.3 ms vs 1.7 ms and 12.2 ms vs (5.9±2.6)ms; all P<0.01]. No significant correlation was found between MD and GLS, left ventricular ejection fraction (LVEF)(r=0.12, P=0.27; r=-0.17, P=0.10). Weak correlations were found between MD and FT3, FT4, TSH(r=-0.34, P=0.01; r=-0.38, P=0.005; r=0.31, P=0.02). Conclusions Primary overt HT is associated with impaired LV deformation and increased systolic dyssynchrony. LV MD is a promising parameter for assessment of myocardial impairment in HT. Key words: Echocardiography; Hypothyroidism; Ventricular function, left; Strain; Mechanical Dispersion; Two-dimensional speckle tracking imaging

Left Ventricular Mechanical Dispersion and Global Longitudinal Strain and Ventricular Arrhythmias in Predialysis and Dialysis Patients

Patients with advanced chronic kidney disease (CKD) have high risk for sudden cardiac death (SCD) and may benefit from implantable cardioverter-defibrillators (ICDs). However, the risk for ICD-related complications is also high in this population. Therefore, there is an unmet need for accurate risk stratification tools to identify patients with CKD at risk for ventricular arrhythmias (VAs), who may benefit from ICD implantation. The aim of this hypothesis-generating study was to investigate the association between left ventricular (LV) mechanical dispersion and LV global longitudinal strain (GLS) measured using two-dimensional speckle-tracking echocardiography and VA and SCD in patients with CKD. Patients with CKD stages 3b to 5 (estimated glomerular filtration rate<45mL/min/1.73m2 or on dialysis) were included and were divided into two groups according to the occurrence of VA or SCD during follow-up. LV mechanical dispersion, as a measure of the temporal heterogeneity of the LV deformation, was measured as the SD of time to peak longitudinal strain of 17 LV segments. The ability of LV mechanical dispersion, LV ejection fraction, and LV GLS to discriminate patients with VA or SCD during follow-up was evaluated using receiver operating characteristic curve analysis. Of 250 patients (66% men; mean age, 61±14years), 16 (6%) experienced VA or SCD during a median follow-up duration of 28months (interquartile range, 16-53months). Using receiver operating characteristic curve analyses, LV GLS (area under the curve=0.79; 95% CI, 0.68-0.89) and LV mechanical dispersion (area under the curve=0.71; 95% CI, 0.61-0.82) showed modest discrimination to identify patients at risk for VA or SCD. In contrast, LV ejection fraction showed poor discrimination (area under the curve=0.60; 95% CI, 0.41-0.78). LV mechanical dispersion along with LV GLS may be an additional valuable risk marker of VA and SCD in predialysis and dialysis patients.

Impact of mitral regurgitation correction (Mitraclip® vs. surgical repair) on left ventricular myocardial performance according to baseline LVEF

Left ventricular (LV) pressure-strain loops (PSLs) have been recently validated as a non-invasive index of myocardial performance. The present study sought to analyze variation in LV function, myocardial work, and energy dispersion in patients with severe mitral regurgitation undergoing percutaneous mitral valve repair (MitraClip ® system) or mitral valve surgery (MVS). Thirty-two patients (mean age: 71 ± 10 years) with severe MR (18 with ischemic cardiomyopathy, 14 with dilated cardiomyopathy) and a LVEF < 50% undergoing MitraClip ® implantation and 15 patients (mean age: 64 ± 13 years) with primary MR and LVEF > 50% undergoing MVS according to ESC guidelines were included in the study. All patients underwent standard and speckle tracking echocardiography (STE) before MitraClip ® /MVS and at 6-month follow-up. Strain traces and valvular event times were used to calculate LV-PSLs and Global cardiac Work (GW), Positive Work (PW), and Negative work (NW) were therefore obtained. As showed in Table 1 , patients undergoing MVS experienced a decrease in LVEF, mechanical dispersion and an increase in cardiac NW after surgery. In patients undergoing MitraClip ® , a similar result was obtained when baseline LVEF was > 40%, whereas patients having a baseline LVEF < 40% did not experience significant changes in LV performance and mechanical dispersion. In patients with severe MR and a LVEF > 40%, either MitraClip ® or MVS have a negative impact on LV performance. The significant increase in mechanical dispersion and negative work, detected by new STE-derived analysis, provides an interesting explanation of these findings.

P1442Age-related increase of left ventricular mechanical dispersion measured with two-dimensional speckle-tracking echocardiography in 254 healthy adults

P1442Age-related increase of left ventricular mechanical dispersion measured with two-dimensional speckle-tracking echocardiography in 254 healthy adults

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.

Lower than expected burden of premature ventricular contractions impairs myocardial function.

AimsWe aimed to explore the burden of frequent premature ventricular contractions (PVCs) associated with myocardial dysfunction in patients with outflow tract arrhythmia (OTA). We hypothesized that this threshold is lower than the previously suggested threshold of 24 000 PVCs/24 h (24%PVC) when systolic function is assessed by strain echocardiography. Furthermore, we aimed to characterize OTA patients with malignant arrhythmic events.Methods and resultsWe included 52 patients referred for OTA ablation (46 ± 12 years, 58% female). Left ventricular global longitudinal strain (GLS) and mechanical dispersion were assessed by speckle tracking echocardiography. A subset underwent cardiac magnetic resonance imaging. PVC burden (%PVC) was assessed by Holter recording. Sinus rhythm QRS duration and PVC QRS duration were recorded from electrocardiogram, and the ratio was calculated (PVC QRS duration / sinus rhythm QRS duration). Median %PVC was 7.2 (0.2–60.0%). %PVC correlated with GLS (R = 0.44, P = 0.002) and with mechanical dispersion (R = 0.48, P < 0.001), but not with ejection fraction (R = 0.22, P = 0.12). %PVC was higher in patients with impaired systolic function by GLS (worse than −18%) compared with patients with normal function (22% vs. 5%, P = 0.001). Greater than 8%PVC optimally identified patients with abnormal GLS (area under the curve 0.79). Serious arrhythmic events occurred in 11/52 (21%) patients characterized by high QRS ratios (1.56 vs. 1.91, P < 0.001).ConclusionsMore than 8%PVC was associated with impaired systolic function by GLS, which is a lower threshold than previously reported. Patients with serious arrhythmic events had higher QRS ratios, which may represent a more malignant phenotype of OTA.

Left ventricular mechanical dispersion is associated with nonsustained ventricular tachycardia in hypertrophic cardiomyopathy

Objective: We assessed the value of speckle tracking two-dimensional (2D) strain echocardiography (2DSE) measured mechanical dispersion (MD) with other imaging and electrocardiographic parameters in differentiating hypertrophic cardiomyopathy (HCM) patients with and without nonsustained ventricular tachycardia (NSVT) on 24-h ambulatory ECG monitoring.Methods and results: We studied 31 patients with HCM caused by the Finnish founder mutation MYBPC3-Q1061X and 20 control subjects with comprehensive 2DSE echocardiography and cardiac magnetic resonance imaging (CMRI). The presence of NSVT was assessed from ambulatory 24-h ECG monitoring.NSVT episodes were recorded in 11 (35%) patients with HCM. MD was significantly higher in HCM patients with NSVT (93 ± 41 ms) compared to HCM patients without NSVT (50 ± 18 ms, p = 0.012) and control subjects (41 ± 16 ms, p < 0.001). MD was the only variable independently associated with the presence of NSVT (OR: 1.60, 95% CI: 1.05–2.45, p = 0.030). Assessed by ROC curves, MD performed best in differentiating between HCM patients with and without NSVT (AUC = 0.81).Conclusions: Increased mechanical dispersion was associated with NSVT in HCM patients on 24-h ambulatory ECG monitoring. Key messagesThe prediction of sudden cardiac death in hypertrophic cardiomyopathy remains a challenge and novel imaging methods are required to identify individuals at risk of malignant ventricular arrhythmias.Mechanical dispersion by speckle tracking echocardiography is associated with NSVT on 24-h ambulatory ECG monitoring in patients with hypertrophic cardiomyopathy

LV mechanical dispersion as a predictor of ventricular arrhythmia in patients with advanced systolic heart failure : A pilot study.

BackgroundMyocardial mechanical dyssynchrony induced by the presence of postinfarction scar and/or conduction abnormalities in patients with a left ventricular ejection fraction (LVEF) of < 35 % may be associated with a greater propensity toward inducing serious ventricular arrhythmia [(ventricular tachycardia (VT), ventricular fibrillation (VF)] and sudden cardiac death. The assessment of regional myocardial function using tissue Doppler echocardiography (TDE) allows for noninvasive analysis of regional mechanical dysfunction (LV mechanical dispersion).AimThe aim of this study was to evaluate the TDE-based mechanical dispersion as a potential echocardiographic predictor of VT/VF.MethodsThe study group consisted of 47 consecutive ambulatory patients with implanted cardiac resynchronization therapy–defibrillator (CRT-D) devices who were divided into two groups: Group 1 (n = 29) comprised patients with recorded episodes of VT/VF, in whom baseline TDE data were available, and group 2 (n = 18) comprised patients without registered VT/VF in the device memory within 4 years after implantation. LV mechanical dispersion was defined as the standard deviation of the time measured from the beginning of the QRS complex to the peak longitudinal strain in apical four-chamber and two-chamber views. A retrospective quantitative assessment of LV regional deformation was based on the color tissue velocity recordings.ResultsThe average time to event after implantation was 345 days. Patients with electrical events demonstrated greater mechanical dispersion: 99.14 ± 33.60 vs. 72.98 ± 19.70, p=0.002.ConclusionDuring the 4-year follow-up, patients with documented VT/VF were characterized by significantly higher LV mechanical dispersion as compared with patients without electrical events. Measurement of LV mechanical dispersion might be helpful in determining the risk of sudden cardiac death.

Abstract 11004: Prediction of Clinical Outcome in Patients With Aortic Stenosis by Left Ventricular Mechanical Dispersion

Introduction: There is a need for new parameters to improve risk stratification and assess outcome in patients with aortic stenosis (AS). Left ventricular (LV) mechanical dispersion by strain echocardiography reflects heterogeneous myocardial contraction and is a novel marker of sudden cardiac death in structural and primary electrical heart disease. We hypothesized that mechanical dispersion provides valuable prognostic information in patients with AS, and that mechanical dispersion can be used as a clinical tool for risk stratification in these patients Methods: We included 55 patients (56% women,75±9 years) with moderate to severe AS. Global longitudinal strain (GLS) was assessed by speckle tracking echocardiography from a 16 LV segments model. Mechanical dispersion was calculated as standard deviation of time from Q/R on ECG to peak strain in 16 LV segments. Results: Average aortic valve area was 0.7±0.2 cm2. Most patients had LV septal hypertrophy (12±2 mm) and preserved LV ejection fraction (EF) (57±10%). Aortic valve replacement (AVR) was performed in 37 (67%) patients. During 38±14 months follow-up, 15(27%) patients died (no 30-day mortality after AVR). LV ejection fraction (EF) and GLS were similar in the survival and non-survival group (58±9% vs. 54±13%, p=0.16, and -17.0±3.4% vs. -16.7±4.0%, p=0.78, respectively). Mechanical dispersion was the only echocardiographic parameter that differed between survivors and non-survivors (56±18ms vs. 69±19ms, p=0.02). C-statistics for mechanical dispersion showed an AUC of 0.70 (0.55-0.86) and a value of &gt; 67 ms indicated worse survival (log rank &lt; 0.01) (Fig.1) Conclusions: LV mechanical dispersion was significantly higher in the AS non-survivors. Increased mechanical dispersion may be an additional risk marker and could give valuable prognostic information in patients with AS and preserved LVEF.

New echocardiographic insights in short QT syndrome: More than a channelopathy?

Short QT syndrome (SQTS) is a congenital ion channel disease characterized by an increased risk of sudden cardiac death. Little is known about the possibility that accelerated repolarization alters mechanical function in SQTS. The study investigated the presence of left ventricular dysfunction and mechanical dispersion, assessed by tissue Doppler imaging (TDI) and speckle tracking echocardiography (STE), and their correlation with QT interval duration and genetics. Fifteen SQTS patients (7 with HERG and 3 with KCNQ1 mutation) were studied. Electrocardiographic and echocardiographic parameters were compared with age- and sex-matched healthy controls. When compared to the control group, SQTS patients showed reduced left ventricular contraction (global longitudinal strain: -16.0% ± 3.4% vs -22.6% ± 1.7%, P < .001; myocardial performance index 0.59 ± 0.17 vs 0.34 ± 0.08, P < .001) and a higher incidence of ejection fraction <55% (odds ratio 11, 95% confidence interval 1.045-374, P = .04). Mechanical dispersion assessed by TDI (P < .01) and STE (P < .001) was higher in the SQTS group than in controls; each parameter showed a significant inverse correlation with QT interval but not with QT dispersion. This study showed that in SQTS systolic function may also be affected. SQTS patients presented a significant dispersion of myocardial contraction. TDI and STE could become part of the evaluation of this rare disease.

Global and Regional Left Ventricular Strain Indices in Post-Myocardial Infarction Patients with Ventricular Arrhythmias and Moderately Abnormal Ejection Fraction

The aim of the study described here was to compare myocardial strains in ischemic heart patients with and without sustained ventricular tachycardia (VT) and moderately abnormal left ventricular ejection fraction (LVEF) to investigate which index could better predict VT on the basis of the analysis of global and regional left ventricular (LV) dysfunction. We studied 467 patients with previous myocardial infarction and LVEF >35%. Fifty-one patients had documented VT, and 416 patients presented with no VT. LV volumes and score index were obtained by 2-D echocardiography. Longitudinal, radial and circumferential strains were determined. Strains of the infarct, border and remote zones were also obtained. There were no differences in standard LV 2-D parameters between patients with and those without VT. Receiver operating characteristic values were −12.7% for global longitudinal strain (area under the curve [AUC] = 0.72), −4.8% for posterior-inferior wall circumferential strain (AUC = 0.80), 61 ms for LV mechanical dispersion (AUC = 0.84), −10.1% for longitudinal strain of the border zone (AUC = 0.86) and −9.2% for circumferential strain of the border zone (AUC = 0.89). In patients with previous myocardial infarction and moderately abnormal LVEF, peri-infarct circumferential strain was the strongest predictor of documented ventricular arrhythmias among all strain quantitative indices. Additionally, strain values from posterior-inferior wall infarctions had a higher association with arrhythmic events compared with global strain.

Mechanical Dispersion Assessed by Myocardial Strain in Patients After Myocardial Infarction for Risk Prediction of Ventricular Arrhythmia

The aim of this study was to investigate whether myocardial strain echocardiography can predict ventricular arrhythmias in patients after myocardial infarction (MI). Left ventricular (LV) ejection fraction (EF) is insufficient for selecting patients for implantable cardioverter-defibrillator (ICD) therapy after MI. Electrical dispersion in infarcted myocardium facilitates malignant arrhythmia. Myocardial strain by echocardiography can quantify detailed regional and global myocardial function and timing. We hypothesized that electrical abnormalities in patients after MI will lead to LV mechanical dispersion, which can be measured as regional heterogeneity of contraction by myocardial strain. We prospectively included 85 post-MI patients, 44 meeting primary and 41 meeting secondary ICD prevention criteria. After 2.3 years (range 0.6 to 5.5 years) of follow-up, 47 patients had no and 38 patients had 1 or more recorded arrhythmias requiring appropriate ICD therapy. Longitudinal strain was measured by speckle tracking echocardiography. The SD of time to maximum myocardial shortening in a 16-segment LV model was calculated as a parameter of mechanical dispersion. Global strain was calculated as average strain in a 16-segment LV model. The EF did not differ between ICD patients with and without arrhythmias occurring during follow-up (34 +/- 11% vs. 35 +/- 9%, p = 0.70). Mechanical dispersion was greater in ICD patients with recorded ventricular arrhythmias compared with those without (85 +/- 29 ms vs. 56 +/- 13 ms, p < 0.001). By Cox regression, mechanical dispersion was a strong and independent predictor of arrhythmias requiring ICD therapy (hazard ratio: 1.25 per 10-ms increase, 95% confidence interval: 1.1 to 1.4, p < 0.001). In patients with an EF >35%, global strain showed better LV function in those without recorded arrhythmias (-14.0% +/- 4.0% vs. -12.0 +/- 3.0%, p = 0.05), whereas the EF did not differ (44 +/- 8% vs. 41 +/- 5%, p = 0.23). Mechanical dispersion was more pronounced in post-MI patients with recurrent arrhythmias. Global strain was a marker of arrhythmias in post-MI patients with relatively preserved ventricular function. These novel parameters assessed by myocardial strain may add important information about susceptibility for ventricular arrhythmias after MI.

Left ventricular mechanical dispersion by tissue Doppler imaging: a novel approach for identifying high-risk individuals with long QT syndrome

AimsThe aim of this study was to investigate whether prolonged and dispersed myocardial contraction duration assessed by tissue Doppler imaging (TDI) may serve as risk markers for cardiac events (documented arrhythmia, syncope, and cardiac arrest) in patients with long QT syndrome (LQTS).Methods and resultsSeventy-three patients with genetically confirmed LQTS (nine double- and 33 single-mutation carriers with previous cardiac events and 31 single-mutation carriers without events) were studied. Myocardial contraction duration was prolonged in each group of LQTS patients compared with 20 healthy controls (P < 0.001). Contraction duration was longer in single-mutation carriers with previous cardiac events compared with those without (0.46 ± 0.06 vs. 0.40 ± 0.06 s, P = 0.001). Prolonged contraction duration could better identify cardiac events compared with corrected QT (QTc) interval in single-mutation carriers [area under curve by receiver-operating characteristic analysis 0.77 [95% confidence interval (95% CI) 0.65–0.89] vs. 0.66 (95% CI 0.52–0.79)]. Dispersion of contraction was more pronounced in single-mutation carriers with cardiac events compared with those without (0.048 ± 0.018 vs. 0.031 ± 0.019 s, P = 0.001).ConclusionDispersion of myocardial contraction assessed by TDI was increased in LQTS patients. Prolonged contraction duration was superior to QTc for risk assessment. These new methods can easily be implemented in clinical routine and may improve clinical management of LQTS patients.