A Test in Context: Myocardial Strain Measured by Speckle-Tracking Echocardiography

The cardiac arrhythmia is characterized by irregular rhythm of heartbeat which could be either too slow ( 100 beats/min) and can happen at any age. The use of pacemaker and defibrillators devices has been suggested for heart arrhythmias patients. The antiarrhythmic medications have been reported for the treatment of cardiac arrhythmias or irregular heartbeats. The diagnosis, symptoms, and treatments of cardiac arrhythmias as well as the radiofrequency ablation, tachycardia, Brugada syndrome, arterial fibrillation, and recent research on the genetics of cardiac arrhythmias have been described here.

Cardiac Arrhythmias: Diagnosis, Symptoms, and Treatments.

The prognostic value of mechanical left ventricular dyssynchrony defined by phase analysis from gated single-photon emission computed tomography myocardial perfusion imaging among patients with coronary heart disease.

BACKGROUND The prognostic relevance of left atrial (LA) morphological and functional variables, including those derived from speckle tracking echocardiography (STE), has been little investigated in veterinary medicine. OBJECTIVES To assess the prognostic value of several echocardiographic variables, with a focus on LA morphological and functional variables in dogs with myxomatous mitral valve disease (MMVD). ANIMALS One-hundred and fifteen dogs of different breeds with MMVD. METHODS Prospective cohort study. Conventional morphologic and echo-Doppler variables, LA areas and volumes, and STE-based LA strain analysis were performed in all dogs. A survival analysis was performed to test for the best echocardiographic predictors of cardiac-related death. RESULTS Most of the tested variables, including all LA STE-derived variables were univariate predictors of cardiac death in Cox proportional hazard analysis. Because of strong correlation between many variables, only left atrium to aorta ratio (LA/Ao > 1.7), mitral valve E wave velocity (MV E vel > 1.3 m/s), LA maximal volume (LAVmax > 3.53 mL/kg), peak atrial longitudinal strain (PALS < 30%), and contraction strain index (CSI per 1% increase) were entered in the univariate analysis, and all were predictors of cardiac death. However, only the MV E vel (hazard ratio [HR], 4.45; confidence interval [CI], 1.76-11.24; P < .001) and LAVmax (HR, 2.32; CI, 1.10-4.89; P = .024) remained statistically significant in the multivariable analysis. CONCLUSIONS AND CLINICAL IMPORTANCE The assessment of LA dimension and function provides useful prognostic information in dogs with MMVD. Considering all the LA variables, LAVmax appears the strongest predictor of cardiac death, being superior to LA/Ao and STE-derived variables.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/jvim.15093

Prognostic value of echocardiographic indices of left atrial morphology and function in dogs with myxomatous mitral valve disease.

AIMS Left atrial (LA) dysfunction can be associated with left ventricular (LV) disorders; however, its clinical significance has not been well-studied in patients with acute heart failure (AHF). We evaluated prognostic power of peak atrial longitudinal strain (PALS) of the left atrium according to heart failure (HF) phenotypes and atrial fibrillation (AF). METHODS AND RESULTS From an AHF registry with 4312 patients, we analysed PALS in 3818 patients. Patients were categorized into PALS tertiles. We also divided the patients according to HF phenotypes [HF with reduced ejection fraction (HFrEF), HF with mid-range ejection fraction (HFmrEF), or HF with preserved ejection fraction (HFpEF)] and presence of AF. The primary outcomes were all-cause mortality and HF hospitalization. PALS was weakly but significantly correlated with LA volume index (r = -0.310, P < 0.001), E/e' (r = -0.245, P < 0.001), and LV ejection fraction (r = 0.371, P < 0.001). A total of 2016 patients (52.8%) experienced adverse clinical events during median follow-up duration of 30.6 months (interquartile ranges 11.6-54.4 months). In the multivariate analysis, PALS was a significant predictor of events [hazard ratio (HR) 0.984, 95% confidence interval (CI) 0.971-0.996; P = 0.012]. Patients with the lowest tertile (HR 1.576, 95% CI 1.219-2.038; P < 0.001) had a higher number of events than those with the highest tertile in the multivariate analysis. In the subgroup analysis, however, PALS was not a prognosticator (HR 0.987, 95% CI 0.974-1.000; P = 0.056) in AF patients. The prognostic power of PALS was not different between HFrEF (HR 0.977, 95% CI 0.969-0.974; P < 0.001), HFmrEF (HR 0.984, 95% CI 0.972-0.996; P = 0.008), and HFpEF (HR 0.980, 95% CI 0.973-0.987; P < 0.001, P for interaction = 0.433). CONCLUSION PALS was a significant prognostic marker in AHF patients. The prognostic power was similar regardless of HF phenotypes, but PALS was not associated with clinical events in AF patients.

Prognostic power of left atrial strain in patients with acute heart failure.

Prognostic value of left ventricular mechanical dyssynchrony by phase analysis in patients with non-ischemic cardiomyopathy with ejection fraction 35-50% and QRS < 150 ms.

Background
Our aim was to assess how atrial fibrillation (AF) induction, chronicity, and RR interval irregularity affect left atrial (LA) function and size in the setting of underlying heart failure (HF), and to determine whether AF effects can be mitigated by vagal nerve stimulation (VNS).

Methods
HF was induced by 4-weeks of rapid ventricular pacing in 24 dogs. Subsequently, AF was induced and maintained by atrial pacing at 600 bpm. Dogs were randomized into control (n = 9) and VNS (n = 15) groups. In the VNS group, atrioventricular node fat pad stimulation (310 μs, 20 Hz, 3–7 mA) was delivered continuously for 6 months. LA volume and LA strain data were calculated from bi-weekly echocardiograms.

Results
RR intervals decreased with HF in both groups (p = 0.001), and decreased further during AF in control group (p = 0.014), with a non-significant increase in the VNS group during AF. LA size increased with HF (p<0.0001), with no additional increase during AF. LA strain decreased with HF (p = 0.025) and further decreased after induction of AF (p = 0.0001). LA strain decreased less (p = 0.001) in the VNS than in the control group. Beat-by-beat analysis showed a curvilinear increase of LA strain with longer preceding RR interval, (r = 0.45, p <0.0001) with LA strain 1.1% higher (p = 0.02) in the VNS-treated animals, independent of preceding RR interval duration. The curvilinear relationship between ratio of preceding and pre-preceding RR intervals, and subsequent LA strain was weaker, (r = 0.28, p = 0.001). However, VNS-treated animals again had higher LA strain (by 2.2%, p = 0.002) independently of the ratio of preceding and pre-preceding RR intervals.

Conclusions
In the underlying presence of pacing-induced HF, AF decreased LA strain, with little impact on LA size. LA strain depends on the preceding RR interval duration.

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Left Atrial Size and Function in a Canine Model of Chronic Atrial Fibrillation and Heart Failure.

https://www.cardiology.theclinics.com/article/S0733-8651(14)00003-4/pdf

Shock Avoidance and the Newer Tachycardia Therapy Algorithms

Global longitudinal strain (GLS) is used to evaluate left ventricular (LV) performance after chemotherapy. Differentiating between reduction in GLS due to clinical change and normal temporal variability in measurement remains a challenge. We quantified interobserver, test-retest variability of GLS by expert observers in relation to variability of GLS quantified for clinical assessment by sonographers in our laboratory. We examined the temporal variability of GLS in 30 patients with normal LV ejection fraction (LVEF >53%) undergoing chemotherapy in the absence of change in medications and clinical symptoms in up to 5 sequential echocardiograms. GLS was quantified using EchoPAC (GE Healthcare, Milwaukee, Wisconsin) and 2-dimensional biplane LVEF was measured from 4- and 2- chamber views. Interobserver test-retest variability of GLS measured in 10 random patients by 2 expert readers was calculated using a one-way analysis of variance. Square root of mean squared error provided the SEM for temporal variability. Baseline LVEF was 59.3 ± 5.1% and remained relatively unchanged over 12 months, p = 0.87. Temporal variability of GLS measured by sonographers was 1.28% and similar to interobserver test-retest variability of GLS measured by expert observers, 1.12% (p = 0.17). Maximum detectable difference in GLS measured by expert observers was similar to that derived from sequential measurements of GLS (3.2% vs 3.6%, respectively). Temporal variability of GLS among clinically stable patients is 1.28% and similar to interobserver test-retest variability of 1.12% measured by expert observers. In conclusion, a reduction in strain >3.2% during sequential echocardiograms under these conditions may be significant.

Temporal Variability of Global Longitudinal Strain in Stable Patients Undergoing Chemotherapy With Trastuzumab

Whereas breast cancer therapy may target cardiovascular system through side effects of surgery, chemotherapy, and radiation, interest has been focused on the impact of trastuzumab [(1)][1], a human epidermal growth factor receptor-2 (HER2) blocker, on left ventricular (LV) function. Maximizing HER2

Adam Goldberg

Papers

Prognostic value of left ventricular mechanical dyssynchrony by phase analysis in patients with non-ischemic cardiomyopathy with ejection fraction 35-50% and QRS < 150 ms.

Left Atrial Size and Function in a Canine Model of Chronic Atrial Fibrillation and Heart Failure.

Shock Avoidance and the Newer Tachycardia Therapy Algorithms

Temporal Variability of Global Longitudinal Strain in Stable Patients Undergoing Chemotherapy With Trastuzumab

Pertuzumab/Trastuzumab Breast Cancer Therapy Is Associated With Complex Hemodynamic Abnormalities.