Cheuk-Man Yu

Predictors of left ventricular reverse remodeling after cardiac resynchronization therapy for heart failure secondary to idiopathic dilated or ischemic cardiomyopathy

Biventricular pacing results in left ventricular (LV) reverse remodeling in heart failure patients with wide QRS complexes. This study examines potential predictors of reverse remodeling. Echocardiography with tissue Doppler imaging was performed at baseline and 3 months after biventricular pacing in 30 patients (21 men and 9 women, mean age 62 +/- 14 years). There were 17 responders to reverse remodeling (defined as a reduction in LV end-systolic volume by >15%) and 13 nonresponders. Responders had significant improvement in 6-minute hall-walking distance (p = 0.006), metabolic equivalents (p = 0.02), peak oxygen uptake (p = 0.02), New York Heart Association functional class (p <0.001), and quality of life (p <0.001); an increase in the sphericity index (p = 0.007), ejection fraction (p <0.001), and diastolic filling time (p = 0.03); a decrease in myocardial performance index (p = 0.02), isovolumic relaxation time (p = 0.004), and mitral regurgitation (p = 0.007); and an improvement in systolic dyssynchrony (SD of the time to peak myocardial systolic contraction of the 12 LV segments as dyssynchrony index) (45.0 +/- 8.3 vs 32.5 +/- 14.5 ms, p = 0.003). In contrast, nonresponders only had a small degree of clinical improvement in New York Heart Association class (p = 0.03) and quality-of-life scores (p = 0.03), without any change in cardiac function, and worsening of systolic dyssynchrony (24.8 +/- 4.5 vs 34.1 +/- 13.5 ms, p = 0.02). When all the above factors were put into univariate and multivariate analyses models, systolic dyssynchrony was the only independent predictor of reverse remodeling (r = -0.76, p <0.001) (beta = -1.54, p = 0.007). A preimplant dyssynchrony index of 32.6 ms (+2 SDs from mean of 88 normal controls) was able to totally segregate responders from nonresponders of biventricular pacing. Thus, responders of LV reverse remodeling were associated with improvement in clinical status, cardiac function, and systolic synchronicity. Direct assessment of systolic synchronicity by tissue Doppler imaging is highly accurate in predicting responders to therapy.

Left Ventricular Reverse Remodeling but Not Clinical Improvement Predicts Long-Term Survival After Cardiac Resynchronization Therapy

Background—In patients with severe heart failure and dilated cardiomyopathy, cardiac resynchronization therapy (CRT) improves left ventricular (LV) systolic function associated with LV reverse remodeling and favorable 1-year survival. However, it is unknown whether LV reverse remodeling translates into a better long-term prognosis and what extent of reverse remodeling is clinically relevant, which were investigated in this study. Methods and Results—Patients (n=141) with advanced heart failure (mean±SD age, 64±11 years; 73% men) who received CRT were followed up for a mean (±SD) of 695±491 days. The extent of reduction in LV end-systolic volume (LVESV) at 3 to 6 months relative to baseline was examined for its predictive value on long-term clinical outcome. The cutoff value for LV reverse remodeling in predicting mortality was derived from the receiver operating characteristic curve. Then the relation between potential predictors of mortality and heart failure hospitalizations were compared by Kaplan-Meier survival analysis, followed by Cox regression analysis. There were 22 (15.6%) deaths, mostly due to heart failure or sudden cardiac death. The receiver operating characteristic curve found that a reduction in LVESV of ≥9.5% had a sensitivity of 70% and specificity of 70% in predicting all-cause mortality and of 87% and 69%, respectively, for cardiovascular mortality. With this cutoff value, there were 87 (61.7%) responders to reverse remodeling. In Kaplan-Meier survival analysis, responders had significantly lower all-cause morality (6.9% versus 30.6%, log-rank &khgr;2=13.26, P=0.0003), cardiovascular mortality (2.3% versus 24.1%, log-rank &khgr;2=17.1, P<0.0001), and heart failure events (11.5% versus 33.3%, log-rank &khgr;2=8.71, P=0.0032) than nonresponders. In the Cox regression analysis model, the change in LVESV was the single most important predictor of all-cause (&bgr;=1.048, 95% confidence interval=1.019 to 1.078, P=0.001) and cardiovascular (&bgr;=1.072, 95% confidence interval=1.033 to 1.112, P<0.001) mortality. Clinical parameters were unable to predict any outcome event. Conclusions—A reduction in LVESV of 10% signifies clinically relevant reverse remodeling, which is a strong predictor of lower long-term mortality and heart failure events. This study suggests that assessing volumetric changes after an intervention in patients with heart failure provides information predictive of natural history outcomes.

Intrathoracic Impedance Monitoring in Patients With Heart Failure. Correlation With Fluid Status and Feasibility of Early Warning Preceding Hospitalization

Background—Patients with heart failure are frequently hospitalized for fluid overload. A reliable method for chronic monitoring of fluid status is therefore desirable. We evaluated an implantable system capable of measuring intrathoracic impedance to identify potential fluid overload before heart failure hospitalization and to determine the correlation between intrathoracic impedance and standard measures of fluid status during hospitalization. Methods and Results—Thirty-three patients with NYHA class III and IV heart failure were implanted with a special pacemaker in the left pectoral region and a defibrillation lead in the right ventricle. Intrathoracic impedance was regularly measured and recorded between the lead and the pacemaker case. During hospitalizations, pulmonary capillary wedge pressure and fluid status were monitored. Ten patients were hospitalized for fluid overload 25 times over 20.7±8.4 months. Intrathoracic impedance decreased before each admission by an average of 12.3±5.3% (P<0.001) over an average of 18.3±10.1 days. Impedance reduction began 15.3±10.6 days (P<0.001) before the onset of worsening symptoms. There was an inverse correlation between intrathoracic impedance and pulmonary capillary wedge pressure (r=−0.61, P<0.001) and between intrathoracic impedance and net fluid loss (r=−0.70, P<0.001) during hospitalization. Automated detection of impedance decreases was 76.9% sensitive in detecting hospitalization for fluid overload, with 1.5 false-positive (threshold crossing without hospitalization) detections per patient-year of follow-up. Conclusions—Intrathoracic impedance is inversely correlated with pulmonary capillary wedge pressure and fluid balance and decreased before the onset of patient symptoms and before hospital admission for fluid overload. Regular monitoring of impedance may provide early warning of impending decompensation and diagnostic information for titration of medication.

TGF-β/Smad3 Signaling Promotes Renal Fibrosis by Inhibiting miR-29

TGF-β/Smad3 signaling promotes fibrosis, but the development of therapeutic interventions involving this pathway will require the identification and ultimate targeting of downstream fibrosis-specific genes. In this study, using a microRNA microarray and real-time PCR, wild-type mice had reduced expression of miR-29 along with the development of progressive renal fibrosis in obstructive nephropathy. In contrast, Smad3 knockout mice had increased expression of miR-29 along with the absence of renal fibrosis in the same model of obstruction. In cultured fibroblasts and tubular epithelial cells, Smad3 mediated TGF-β(1)-induced downregulation of miR-29 by binding to the promoter of miR-29. Furthermore, miR-29 acted as a downstream inhibitor and therapeutic microRNA for TGF-β/Smad3-mediated fibrosis. In vitro, overexpression of miR-29b inhibited, but knockdown of miR-29 enhanced, TGF-β(1)-induced expression of collagens I and III by renal tubular cells. Ultrasound-mediated gene delivery of miR-29b either before or after established obstructive nephropathy blocked progressive renal fibrosis. In conclusion, miR-29 is a downstream inhibitor of TGF-β/Smad3-mediated fibrosis and may have therapeutic potential for diseases involving fibrosis.

Biventricular pacing in patients with bradycardia and normal ejection fraction.

BACKGROUND Observational studies suggest that conventional right ventricular apical pacing may have a deleterious effect on left ventricular function. In this study, we examined whether biventricular pacing is superior to right ventricular apical pacing in preventing deterioration of left ventricular systolic function and cardiac remodeling in patients with bradycardia and a normal ejection fraction. METHODS In this prospective, double-blind, multicenter study, we randomly assigned 177 patients in whom a biventricular pacemaker had been successfully implanted to receive biventricular pacing (89 patients) or right ventricular apical pacing (88 patients). The primary end points were the left ventricular ejection fraction and left ventricular end-systolic volume at 12 months. RESULTS At 12 months, the mean left ventricular ejection fraction was significantly lower in the right-ventricular-pacing group than in the biventricular-pacing group (54.8+/-9.1% vs. 62.2+/-7.0%, P<0.001), with an absolute difference of 7.4 percentage points, whereas the left ventricular end-systolic volume was significantly higher in the right-ventricular-pacing group than in the biventricular-pacing group (35.7+/-16.3 ml vs. 27.6+/-10.4 ml, P<0.001), with a relative difference between the groups in the change from baseline of 25% (P<0.001). The deleterious effect of right ventricular apical pacing occurred in prespecified subgroups, including patients with and patients without preexisting left ventricular diastolic dysfunction. Eight patients in the right-ventricular-pacing group (9%) and one in the biventricular-pacing group (1%) had ejection fractions of less than 45% (P=0.02). There was one death in the right-ventricular-pacing group, and six patients in the right-ventricular-pacing group and five in the biventricular-pacing group were hospitalized for heart failure (P=0.74). CONCLUSIONS In patients with normal systolic function, conventional right ventricular apical pacing resulted in adverse left ventricular remodeling and in a reduction in the left ventricular ejection fraction; these effects were prevented by biventricular pacing. (Centre for Clinical Trials number, CUHK_CCT00037.)

Tissue Doppler imaging provides incremental prognostic value in patients with systemic hypertension and left ventricular hypertrophy.

Objectives We sought to determine the prognostic value of left ventricular (LV) mitral annular velocities measured by tissue Doppler imaging (TDI) in hypertensive patients with echocardiographic evidence of LV hypertrophy. Background Echo LV hypertrophy and LV geometry provide additional predictive value of all-cause mortality beyond traditional cardiovascular risk factors. Limited data exist regarding the predictive value of TDI velocities for cardiovascular risk stratification in treated hypertensive patients. Methods Two-dimensional and Doppler echocardiograms were obtained in 252 consecutive subjects, including 174 subjects with systemic hypertension and 78 age-matched normal subjects. The end point was cardiac death in subsequent median follow-up of 19 months. Results Nineteen patients (7.54%) died of cardiac causes. The TDI mitral annulus systolic velocity and the early diastolic mitral annular velocity (Em) were significantly lower in the non-survivors (all P < 0.001). The pseudonormal (PN) or restrictive filling pattern (RFP) was associated with cardiac mortality. The other parameters associated with cardiac mortality were LV ejection fraction, LV mass index, inter-ventricular septal wall thickness in diastole and the ratio of early mitral inflow to early myocardial velocity. In multivariate analysis, Em, inter-ventricular septal wall thickness in diastole and either PN or RFP were the strongest predictors. The addition of Em < 3.5 cm/s significantly improved the outcome of a model that contained clinical risk factors, inter-ventricular septal wall thickness in diastole > 1.4 cm and either PN or RFP (P = 0.043). Conclusions Early diastolic mitral annulus velocity measured by TDI provides prognostic information, incremental to clinical data and standard echocardiographic variables, for risk stratification of hypertensive patients under treatment.

miR-29 Inhibits Bleomycin-induced Pulmonary Fibrosis in Mice

Loss of microRNA-29 (miR-29) is known to be a mechanism of transforming growth factor-β (TGF-β)-mediated pulmonary fibrosis, but the therapeutic implication of miR-29 for pulmonary fibrosis remains unexplored. The present study investigated whether miR-29 had therapeutic potential for lung disease induced by bleomycin in mice. In addition, the signaling mechanisms that regulated miR-29 expression were investigated in vivo and in vitro. We found that miR-29 was a downstream target gene of Smad3 and negatively regulated by TGF-β/Smad signaling in fibrosis. This was evidenced by the findings that mice or pulmonary fibroblasts null for Smad3 were protected against bleomycin or TGF-β1-induced loss of miR-29 along with fibrosis in vivo and in vitro. Interestingly, overexpression of miR-29 could in turn negatively regulated TGF-β and connective tissue growth factor (CTGF) expression and Smad3 signaling. Therefore, Sleeping Beauty (SB)-mediated miR-29 gene transfer into normal and diseased lung tissues was capable of preventing and treating pulmonary fibrosis including inflammatory macrophage infiltration induced by bleomycin in mice. In conclusion, miR-29 is negatively regulated by TGF-β/Smad3 and has a therapeutic potential for pulmonary fibrosis. SB-mediated miR-29 gene therapy is a non-invasive therapeutic strategy for lung disease associated with fibrosis.

Sensitivity and positive predictive value of implantable intrathoracic impedance monitoring as a predictor of heart failure hospitalizations: the SENSE-HF trial

AIMS Early recognition of impending decompensation and timely intervention may prevent heart failure (HF) hospitalization. We investigated the performance of OptiVol® intrathoracic fluid monitoring for the prediction of HF events in chronic HF patients newly implanted with a device (implantable cardioverter-defibrillator with or without cardiac resynchronization therapy). METHODS AND RESULTS SENSE-HF was a prospective, multi-centre study that enrolled 501 patients. Phase I (double blinded, 6 months) determined the sensitivity and positive predictive value (PPV) of the OptiVol data in predicting HF hospitalizations. Of 58 adjudicated HF hospitalizations that occurred during the first 6 months in Phase I, 12 were predicted by OptiVol (sensitivity = 20.7%). Sensitivity appeared to be dynamic in nature and at the end of Phase I, had increased to 42.1%. With 253 OptiVol detections, PPV for Phase I was 4.7%. Phase II/III (unblinded, 18 months) determined the PPV of the first OptiVol Patient Alert for detection of worsening HF status with signs and/or symptoms of pulmonary congestion. A total of 233 patients noted such an OptiVol alert and for 210, HF status was evaluated within 30 days. Heart failure status had worsened for 80 patients (PPV = 38.1%). CONCLUSIONS An intrathoracic impedance-derived fluid index had low sensitivity and PPV in the early period after implantation of a device in chronic HF patients. Sensitivity improved within the first 6 months after implant. Further studies are needed to assess the place of this monitoring technology in the clinical management of patients with HF.

Coronary artery disease and cardiovascular outcomes in patients with non-alcoholic fatty liver disease

Objective Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome and is associated with cardiovascular risk. The aim of this study was to determine the role of fatty liver in predicting coronary artery disease and clinical outcomes in patients undergoing coronary angiogram. Methods This was a prospective cohort study carried out in a University hospital. Consecutive patients who underwent coronary angiogram had ultrasound screening for fatty liver. Significant cardiovascular disease was defined as ≥50% stenosis in at least one coronary artery. The primary outcome was a composite end point comprising cardiovascular deaths, non-fatal myocardial infarction and the need for further coronary intervention during prospective follow-up. Results Among 612 recruited patients, 356 (58.2%) had fatty liver by ultrasonography, 318 (52.0%) had elevated serum alanine aminotransferase and 465 (76.0%) had significant coronary artery disease. Coronary artery disease occurred in 84.6% of patients with fatty liver and 64.1% of those without fatty liver (p<0.001). After adjusting for demographic and metabolic factors, fatty liver (adjusted OR 2.31; 95% CI 1.46 to 3.64) and alanine aminotransferase level (adjusted OR 1.01; 95% CI 1.00 to 1.02) remained independently associated with coronary artery disease. At a mean follow-up of 87±22 weeks, 30 (10.0%) patients with fatty liver and 18 (11.0%) patients without fatty liver reached the composite clinical end point (p=0.79). Conclusions In patients with clinical indications for coronary angiogram, fatty liver is associated with coronary artery disease independently of other metabolic factors. However, fatty liver cannot predict cardiovascular mortality and morbidity in patients with established coronary artery disease.

Understanding Nonresponders of Cardiac Resynchronization Therapy—Current and Future Perspectives

Introduction: Cardiac resynchronization therapy (CRT) is now an established nonpharmacologic therapy for advanced heart failure with electromechanical delay. Despite compelling evidence of the benefits of CRT, one troubling issue is the lack of a favorable response in about one‐third of patients.