The role of contractile dyssynchrony in pacing-induced cardiomyopathy: detailed assessment using index of contractile asymmetry.

AIMS: The pathophysiological effects of chronic right ventricular pacing and the role of right ventricular lead position are not well understood. Therefore, we investigated the association between left ventricular contractile dyssynchrony and pacing-induced cardiomyopathy (PICM) in patients with chronic right ventricular pacing. Furthermore, we assessed the association between right ventricular lead location and left ventricular contractile dyssynchrony. METHODS: This was a retrospective study using data from 153 pacemaker patients with normal (≥ 50%) pre-implant left ventricular ejection fraction (LVEF). Baseline and follow-up echocardiograms were analyzed, and PICM was defined as LVEF < 50% with ≥ 10% decrease in LVEF after pacemaker implantation. Relative index of contractile asymmetry (rICA), a novel strain rate-based method, was calculated to quantify left ventricular contractile dyssynchrony between opposing walls in the three apical views. Right ventricular lead position was categorized into anterior septum, posterior septum, free wall, and apex based on contrast-enhanced cardiac computed tomography. RESULTS: Forty-seven (31%) developed PICM. Overall contractile dyssynchrony, measured by mean rICA, was higher in the PICM group compared with the non-PICM group (1.19 ± 0.21 vs. 1.03 ± 0.19, p < 0.001). Left ventricular anterior-inferior dyssynchrony, assessed in the apical two-chamber view, was independently associated with PICM (p < 0.001). Thirty-seven (24%) leads were implanted anterior septal, 11 (7.2%) posterior septal, 74 (48.4%) apical, and 31 (20.3%) free wall. Left ventricular anterior-inferior dyssynchrony was significantly different between the four pacing lead locations (p < 0.01) with the highest rICA observed in the posterior septal group (1.30 ± 0.37). CONCLUSIONS: PICM is significantly associated increased contractile dyssynchrony assessed by rICA. This study suggests that especially left ventricular dyssynchrony in the anterior-inferior direction is associated with PICM, and pacing the right ventricular posterior septum resulted in the highest degree of anterior-inferior dyssynchrony. Quantification of left ventricular dyssynchrony by rICA provides important insights to the potential pathophysiology of PICM and the impact of right ventricular lead position.

Seismocardiography as a tool for assessment of bi-ventricular pacing.

Objective.Conduction-induced heart failure in patients with left bundle branch block (LBBB) can benefit from cardiac resynchronization therapy (CRT). However, some patients are non-responders to the therapy with one contributing factor being poor optimization of the atrioventricular (AV) pacing delay. In this study, we have investigated the pacing-induced changes in the seismocardiogram (SCG).Approach.14 patients with heart failure, LBBB, and CRT were included. SCG was recorded with pacing turned on and off. Based on a mean SCG heartbeat from each patient, fiducial points were annotated, and cardiac timing intervals (CTI) and amplitudes were derived. These were compared between the CRT group and a group of healthy normal subjects (n= 14). Echocardiography was also used to derive CTI. Intervals derived from the SCG and echocardiogram were correlated.Main results.The isovolumetric contraction time (IVCT) derived from SCG was significantly shorter in the CRT group when the pacemaker was turned on (63.2-52.6 ms,p= 0.027). The first peak-to-peak amplitude in the systolic complex was significantly larger with the pacemaker turned on (p= 0.002), as well as the ∣max-min∣ amplitude in the systolic complex (p= 0.003). Isovolumetric relaxation time and left ventricular ejection time (LVET) were not significantly different between pacemaker settings. Compared to normal subjects, IVCT was significantly prolonged with the pacemaker turned off. All amplitudes were significantly larger in the healthy subject group. IVCT and LVET derived from SCG were significantly correlated to the echocardiogram.Significance.IVCT shortened and SCG amplitudes increased in response to CRT, indicating a more efficient ventricular contraction. This demonstrates the possibility to detect cardio-mechanic changes in response to treatment with the SCG. However, for the patients the systolic part of the SCG was abnormal and difficult to characterize, raising concerns about the correct interpretation of the SCG.

Total average diastolic longitudinal displacement by colour tissue doppler imaging as an assessment of diastolic function.

BACKGROUND: The current method for a non-invasive assessment of diastolic dysfunction is complex with the use of algorithms of many different echocardiographic parameters. Total average diastolic longitudinal displacement (LD), determined by colour tissue Doppler imaging (TDI) via the measurement of LD during early diastole and atrial contraction, can potentially be used as a simple and reliable alternative. METHODS: In 206 patients, using GE Healthcare Vivid E7 and 9 and Echopac BT11 software, we determined both diastolic LD, measured in the septal and lateral walls in the apical 4-chamber view by TDI, and the degree of diastolic dysfunction, based on current guidelines. Of these 206 patients, 157 had cardiac anomalies that could potentially affect diastolic LD such as severe systolic heart failure (n = 45), LV hypertrophy (n = 49), left ventricular (LV) dilation (n = 30), and mitral regurgitation (n = 33). Intra and interobserver variability of diastolic LD measures was tested in 125 patients. RESULTS: A linear relationship between total average diastolic LD and the degree of diastolic dysfunction was found. A total average diastolic LD of 10 mm was found to be a consistent threshold for the general discrimination of patients with or without diastolic dysfunction. Using linear regression, total average diastolic LD was estimated to fall by 2.4 mm for every increase in graded severity of diastolic dysfunction (ß = -0.61, p-value <0.001). Patients with LV hypertrophy had preserved total average diastolic LD despite being classified as having diastolic dysfunction. Reproducibility of LD measures was acceptable. CONCLUSIONS: There is strong evidence suggesting that patients with a total average diastolic LD under 10 mm have diastolic dysfunction.

Concordance and reproducibility between M-mode, tissue Doppler imaging, and two-dimensional strain imaging in the assessment of mitral annular displacement and velocity in patients with various heart conditions.

AIMS: Mitral annular (MA) displacement reflects longitudinal left ventricular (LV) deformation and systolic velocity measurements reflect the rate of contraction; both are valuable in the diagnosis and prognosis of cardiac disease. The aim of this study was to test the agreement and reproducibility between motion mode (M-mode), colour tissue Doppler imaging (TDI), and two-dimensional strain imaging (2DSI) when measuring MA displacement and systolic velocity. METHODS AND RESULTS: Using GE Healthcare Vivid 7 and E9 and Echopac BT11 software, MA displacement and velocity measurements by 2DSI, TDI, and M-mode determined in the septal and lateral walls in the apical four-chamber view were assessed in 50 control subjects and in 168 patients with various cardiac anomalies known to affect longitudinal displacement such as heart failure, mitral regurgitation, LV hypertrophy, and LV dilation. Intra- and inter-observer variability were tested using the Bland-Altman method in 125 patients. A relatively low bias between M-mode and TDI with respect to MA displacement (mean difference ± 1.96 standard deviation: 0.08 ± 0.35 cm) and a low bias between TDI and 2DSI with respect to MA peak systolic velocity (-0.13 ± 1.87 cm/s) were found. Reproducibility was acceptable for all methods with TDI having the lowest intra- and inter-observer variability. CONCLUSION: LV function could be assessed in terms of MA displacement and systolic velocity using M-mode, TDI, and 2DSI. None of the measurement techniques are, however, interchangeable. Overall, TDI seems to be the most robust method, having the lowest observer variability.

Atrial fibrillation in aortic stenosis--echocardiographic assessment and prognostic importance.

BACKGROUND: Atrial fibrillation (AFib) exists more frequently in patients with aortic stenosis (AS) than in patients without, and AFib may be a sign of progressive deterioration of AS. Echocardiographic assessment of AS in sinus rhythm is well documented, however, little is known about AFib in AS since such patients often are excluded from clinical echocardiographic trials. AIM: The purpose of this study was to assess the prognostic importance of AFib in AS. METHODS: The study was designed as a single-center case-control study. Patients with AS and AFib were enrolled as cases (n = 103) and subsequently matched to controls (103 patients with AS but sinus rhythm). Cases and controls were matched according to age, gender and severity of AS. Primary outcome was all cause mortality and follow-up was 100% complete. RESULTS: Compared to controls the group with AFib had lower mean ejection fraction (42% vs. 49%; p < 0.001) and stroke volume (47 mL vs. 55 mL; p = 0.004), but higher heart rate (81 bpm vs. 68 bpm; p < 0.001) and no significant difference with regard to cardiac output (3.8 L vs. 4.0 L; p = 0.29). Accordingly, aortic jet velocity and gradients were significantly lower in AFib compared to controls but there were no differences (p = 0.38) in aortic valve area calculated by the continuity equation. During a median follow-up of 2.3 years (IQR: 1.2-3.6), 70 (34%) patients with AS died: 42 patients with AFib and 28 patients with sinus rhythm (p < 0.02). After adjusting for echocardiographic significant differences, AFib remained an independent predictor of mortality (HR 2.72 (95% CI: 1.12-6.61), p < 0.03). There was no significant interaction (p = 0.62) between AFib and AS on the risk of mortality, indicating that AFib predicted bad outcome regardless of the severity of AS. CONCLUSIONS: AFib is an independent risk factor in patients with AS and the prognostic impact of AFib seems to be the same despite the severity of AS.

Tissue-Doppler assessment of cardiac left ventricular function during short-term adjuvant epirubicin therapy for breast cancer.

BACKGROUND: It has been hypothesized that the extent of acute anthracycline-induced cardiotoxicity reflects the risk for late development of heart failure. The aim of this study was to examine if short-term changes in cardiac function can be detected even after low-dose adjuvant epirubicin therapy for breast cancer when using Doppler tissue imaging of longitudinal left ventricular function. METHODS: Eighty consecutive women in good cardiopulmonary health scheduled to undergo adjuvant treatment for breast cancer were included. They were examined using echocardiography and Doppler tissue imaging before and after three treatment series of epirubicin (mean cumulative dose, 273.7 ± 46.6 mg/m(2); median time interval, 9 weeks; range, 47-113 days). RESULTS: Apart from a marginal reduction in E/A ratio, none of the conventional Doppler echocardiographic or Doppler tissue imaging indices of systolic and diastolic function were affected during epirubicin treatment. CONCLUSIONS: In contrast to several previous studies using tissue Doppler and conventional echocardiography, this study did not document relevant short-term effects of low-dose epirubicin treatment on heart function.