Effect of cardiac resynchronization therapy on myocardial gene expression in patients with nonischemic dilated cardiomyopathy.
ABSTRACT Cardiac resynchronization therapy (CRT) improves echocardiographic measures of ventricular structure and function in the failing heart. To determine whether or not these changes are representative of true biologic reverse ventricular remodeling or simply an artifact of an improved contraction pattern, we evaluated changes in myocardial gene expression typical of reverse remodeling before and after chronic CRT.
Optimally medically treated patients with nonischemic heart failure meeting standard clinical criteria for CRT were enrolled. Before implantation of a CRT device, baseline echocardiogram and endomyocardial biopsies were obtained. These studies were repeated after 6 months of CRT. Using quantitative reverse-transcriptase polymerase chain reaction, the amount of messenger RNA for selected genes regulating contractile function (sarcoplasmic reticulum Ca2+ ATPase, alpha- and beta-myosin heavy chain [MHC] isoforms, phospholamban [PLB]), and pathologic hypertrophy (beta-MHC and atrial natriuretic peptide [ANP]) was determined from biopsy samples. Changes in gene expression (baseline to 6 months) were determined and correlated to changes in echocardiographic remodeling parameters. Ten patients were enrolled in the study, with 7 completing both baseline and follow-up biopsies and echocardiograms. On average, a significant increase was observed in alpha-MHC and PLB gene expression from baseline to 6 months (P = .016 for both). Beta-MHC levels tended to decrease with CRT (P = .078). Increased alpha-MHC levels correlated best with decreases in left ventricular end-diastolic dimension (P = .073, r = -0.71) and reductions in mitral regurgitation. No significant correlation between ejection fraction and gene expression was found.
These changes in myocardial gene expression support the occurrence of reverse remodeling during chronic CRT. The changes are similar to those reported previously with beta-blockade, but were seen on top of standard drug therapies for heart failure.
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ABSTRACT: Heart failure (HF) is a global phenomenon, and the overall incidence and prevalence of the condition are steadily increasing. Medical therapies have proven efficacious, but only a small number of pharmacological options are in development. When patients cease to respond adequately to optimal medical therapy, cardiac resynchronization therapy has been shown to improve symptoms, reduce hospitalizations, promote reverse remodelling, and decrease mortality. However, challenges remain in identifying the ideal recipients for this therapy. The field of mechanical circulatory support has seen immense growth since the early 2000s, and left ventricular assist devices (LVADs) have transitioned over the past decade from large, pulsatile devices to smaller, more-compact, continuous-flow devices. Infections and haematological issues are still important areas that need to be addressed. Whereas LVADs were once approved only for 'bridge to transplantation', these devices are now used as destination therapy for critically ill patients with HF, allowing these individuals to return to the community. A host of novel strategies, including cardiac contractility modulation, implantable haemodynamic-monitoring devices, and phrenic and vagus nerve stimulation, are under investigation and might have an impact on the future care of patients with chronic HF.Nature Reviews Cardiology 12/2012; · 10.40 Impact Factor
- Circulation Arrhythmia and Electrophysiology 06/2012; 5(3):594-603. · 5.95 Impact Factor
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ABSTRACT: The objective of this study was to test the hypothesis that combining assessment of baseline radial strain dyssynchrony index (SDI), that expressed both left ventricular (LV) dyssynchrony and residual myocardial contractility, and of acute changes in this index can yield more accurate prediction of mid-term responders and long-term outcome after cardiac resynchronization therapy (CRT). Radial SDI for 75 CRT patients was calculated as the average difference between peak and end-systolic speckle tracking strain from 6 segments of the mid-LV short-axis view before and 8 ± 2 days after CRT. Mid-term responder was defined as ≥15% decrease in LV end-systolic volume 6 ± 2 months after CRT. Long-term outcome was tracked over 5 years. Baseline radial SDI ≥6.5% is considered predictive of responder and favorable outcome, as previously reported. Acute reduction in radial SDI ≥1.5% was found to be the best predictor of mid-term responders with CRT. Furthermore, patients with acute reductions in radial SDI ≥1.5% were associated with a significantly more favorable long-term outcome after CRT than those with radial SDI <1.5% (log rank P < 0.001). An important findings were that baseline radial SDI ≥6.5% and acute reductions in radial SDI ≥1.5% in 42 patients were associated with the highest event-free survival rate of 92%, whereas, 21 patients corresponding values of <6.5% and <1.5% were associated with low event-free survival rate of 46% (log rank P < 0.001). Combined assessment of baseline radial SDI and its acute reduction after CRT may have clinical implications for predicting responders and thus patients' care.Echocardiography 10/2013; · 1.26 Impact Factor