Dyssynchrony and the risk of ventricular arrhythmias

OBJECTIVES: The aim of our study was to evaluate the relationship between left ventricular (LV) dyssynchrony and the risk of ventricular tachycardia (VT) or ventricular fibrillation (VF) in patients enrolled in the MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy) trial. BACKGROUND: Intraventricular mechanical dyssynchrony might be an important factor in ventricular arrhythmogenesis by enhancing electrical heterogeneity in heart failure patients. The effects of dyssynchrony have not yet been evaluated in a large cohort of implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy with defibrillator (CRT-D) patients. METHODS: LV dyssynchrony was measured at baseline and at 12-months by speckle-tracking echocardiography, defined as the standard deviation of time to peak systolic strain in 12 LV myocardial segments. The endpoint was the first VT/VF/death or VT/VF. LV dyssynchrony was evaluated in 764 left bundle branch block (LBBB) patients and in 312 non-LBBB patients. RESULTS: Baseline LV dyssynchrony was not predictive of VT/VF/death or VT/VF in LBBB or non-LBBB patients in either treatment arm. In CRT-D patients with LBBB, improvement in LV dyssynchrony over a year was associated with significantly lower incidence of VT/VF/death (p < 0.001) and VT/VF (p < 0.001) compared to ICD patients and to CRT-D patients with unchanged or worsening dyssynchrony. Among LBBB patients, 15% decrease in LV dyssynchrony was associated with lower risk of VT/VF/death (hazard ratio: 0.49, 95% confidence interval: 0.24 to 0.99, p = 0.049) and VT/VF (hazard ratio: 0.30, 95% confidence interval: 0.12 to 0.77, p = 0.009) as compared to ICD patients. Patients without LBBB receiving CRT-D did not show reduction in VT/VF/death or in VT/VF in relation to improving dyssynchrony when evaluating cumulative event rates or risk of events. CONCLUSIONS: Baseline LV dyssynchrony did not predict VT/VF/death or VT/VF in mild heart failure patients with or without LBBB. CRT-induced improvement of LV dyssynchrony was associated with significant reduction of ventricular arrhythmias in patients with LBBB. (Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy [MADIT-CRT]; NCT00180271)

Clinical and Hemodynamic Effects of Percutaneous Edge-to-Edge Mitral Valve Repair in Atrial Versus Ventricular Functional Mitral Regurgitation.

The present study aims to assess the clinical and hemodynamic impact of percutaneous edge-to-edge mitral valve repair with MitraClip in patients with atrial functional mitral regurgitation (A-FMR) compared with ventricular functional mitral regurgitation (V-FMR). Mitral regurgitation (MR) grade, functional status (New York Heart Association class), and major adverse cardiac events (MACE; all-cause mortality or hospitalization for heart failure) were evaluated in 52 patients with A-FMR and in 307 patients with V-FMR. In 56 patients, hemodynamic assessment during exercise echocardiography was performed before and 6 months after intervention. MR reduction after MitraClip implantation was noninferior in A-FMR compared with V-FMR (MR grade ≤2 at 6 months in 94% vs 82%, respectively, p <0.001 for noninferiority) and was associated with improvement of functional status (New York Heart Association class ≤2 at 6 months in 90% vs 80%, respectively, p = 0.2). Hemodynamic assessment revealed that cardiac output at 6 months was higher in A-FMR at rest (5.1 ± 1.5 L/min vs 3.8 ± 1.5 L/min, p = 0.002) and during peak exercise (7.9 ± 2.4 L/min vs 6.1 ± 2.1 L/min, p = 0.02). In addition, the reduction in systolic pulmonary artery pressure at rest was more pronounced in A-FMR: Δ SPAP -13.1 ± 15.1 mm Hg versus -2.2 ± 13.3 mm Hg (p = 0.03). MACE rate at follow-up was significantly lower in A-FMR versus V-FMR, with an adjusted odds ratio of 0.46 (95% confidence interval 0.24 to 0.88), which was caused by a reduction in hospitalization for heart failure. In conclusion, percutaneous edge-to-edge mitral valve repair with MitraClip is at least as effective in A-FMR as in V-FMR in reducing MR. However, the hemodynamic improvement and reduction of MACE were significantly better in A-FMR

Comprehensive assessment of patients with aortic valve disease by non-invasive cardiac imaging

Today, invasive coronary angiography is still the gold standard to perform the diagnosis of coronary artery disease. But it is an invasive procedure that carries non negligible morbidity (1.5%) and mortality (0.15%), and results in high costs. Less invasive and more cost-effective techniques are highly desirable. Over the past 15 years, substantial advances have been made in non-invasive cardiac imaging. In the first part of this work, we prospectively evaluated the diagnostic accuracy of 40-slice multidetector CT (MDCT) to detect coronary artery disease prior to cardiac valve surgery in 82 patients. On a per-patient basis, MDCT correctly identified 14/15 patients with (sensitivity 93%) and 60/67 patients without coronary disease (specificity 90%). Performing invasive angiography only in case of abnormal CT might have avoided invasive angiography in 60/82 (73%) patients without coronary disease. Thus, MDCT could be potentially useful in the preoperative evaluation of such patients, allowing to avoid systematic cardiac catheterization in a large number of patients. Magnetic resonance coronary angiography (MRCA) has also emerged as a promising alternative due to the lack of ionizing radiation and absence of iodinated contrast injection. Therefore, we compared diagnostic accuracy of whole-heart MRCA and MDCT, against QCA, to identify >50% stenosis basis in 77 patients. WH-MRCA acquisition failed in a high number of patients. This was caused by an unstable breathing pattern or drift of the diaphragm position. Because of higher success rate, MDCT had higher diagnostic accuracy than WH-MRCA to detect coronary stenosis. Thus MDCT is superior to WH-MRCA, however WH-MRCA can perform as well as CT in interpretable segments with adequate image quality. In the second part of this work, to evaluate whether MDCT and cardiac magnetic resonance (cMR) might allow simultaneous assessment of aortic valve area (AVA), we compared measurements of AVA by MDCT to cMR, transesophageal and transthoracic echocardiography. AVA by MDCT and cMR correlated highly with AVA by other techniques. In our study, we compared 3 planimetric approaches to AVA calculated by the continuity equation using TTE. We did observe excellent correlations between planimetric and continuity equation-derived AVA, but all 3 planimetric measures were found to overestimate continuity equation AVA. A potential explanation for this observation could be that we measure different aortic valve orifices. Indeed planimetric techniques measure the true dimensions of the anatomical orifice, whereas the continuity equation measures the "effective" orifice area. The ability of MDCT and cMR to accurately assess aortic valve area at the time of non-invasive coronary imaging, places these techniques in a strong position for the comprehensive assessment of such patients. However, despite these good results, it must nonetheless be emphasized that to be acceptable in daily clinical practice, a strategy in which invasive coronary angiography would not be performed systematically but rather selectively in only a subset of patients, requires a perfect sensitivity for disease detection in individual patients. Unfortunately, the present work shows that MDCT and WH-MRCA have not yet reached such a level of accuracy. Finally, these tests are not a substitute for other imaging techniques in all cardiovascular conditions. Unlike an echocardiogram machine, the MRI and MDCT scanners cannot be brought to the bedside of an acutely ill patient.(MED 3) -- UCL, 200

Which biomarkers do clinicians need for diagnosis and management of heart failure with reduced ejection fraction?

While there have been significant recent advances in the medical management of chronic HF (including the use of beta-blockers, angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, and aldosterone blockers), the ability to characterize, monitor, and predict a patient's response to HF therapy is poor.Risk stratification is important in patients with chronic heart failure and enables informed decisions about treatment and end-of-life care. Clinical parameters, such as advanced age, higher NYHA functional class, reduced left ventricular ejection fraction, lower body mass index, renal dysfunction, and anemia have all been associated with poor outcomes in HF. More recently, heart failure biomarkers have considerably changed the way we take care of our HF patients. BNP and NT-proBNP are endorsed by current guidelines and are now the gold standard biomarkers to confirm the diagnosis and to evaluate the prognosis of heart failure. Studies on natriuretic peptide-guided HF therapy look promising. Novel biomarkers, such soluble ST2, growth differentiation factor-15, highly sensitive troponins and Galectin-3, show potential in assessing prognosis beyond the established natriuretic peptides, but their role in the clinical care of the patient is still partially defined and more studies are needed