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Aims The HINODE study aimed to analyse rates of mortality, appropriately treated ventricular arrhythmias (VA), and heart failure in Japanese patients and compared with those in Western patients. Methods and results After treatment decisions following contemporary practice in Japan, patients were prospectively enrolled into four cohorts: (i) internal cardioverter-defibrillator (ICD), (ii) cardiac resynchronization therapy (CRT) defibrillator (CRT-D), (iii) standard medical therapy (‘non-device’: ND), or (iv) pacing (indicated for CRT; received pacemaker or CRT pacing). Cohorts 1–3 required a left ventricular ejection fraction ≤35%, a history of heart failure, and a need for primary prevention of sudden cardiac death based on two to five previously identified risk factors. Endpoint outcomes were adjudicated by the independent committees. ICD and CRT-D cohorts, considered as high-voltage (HV) cohorts, were pooled for Kaplan–Meier analysis and propensity-matched to Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate Therapy (MADIT-RIT) arm B and C patients. The study enrolled 354 patients followed for 19.6 ± 6.5 months, with a minimum of 12 months. Propensity-matched HV cohorts showed comparable VA (P = 0.61) and mortality rates (P = 0.29) for HINODE and MADIT-RIT. The ND cohort presented a high crossover rate to ICD therapy (6.1%, n = 7/115), and the CRT-D cohort showed elevated mortality rates. The pacing cohort revealed that patients implanted with pacemakers had higher mortality (26.0%) than those with CRT-Pacing (8.4%, P = 0.05). Conclusions The mortality and VA event rates of landmark trials are applicable to patients with primary prevention in Japan. Patients who did not receive guideline-indicated CRT devices had poor outcomes. [ABSTRACT FROM AUTHOR]

Introduction: MARVEL 2 assessed the efficacy of mechanical atrial sensing by a ventricular leadless pacemaker, enabling a VDD pacing mode. The behavior of the enhanced MARVEL 2 algorithm during variable atrio‐ventricular conduction (AVC) and/or arrhythmias has not been characterized and is the focus of this study. Methods: Of the 75 patients enrolled in the MARVEL 2 study, 73 had a rhythm assessment and were included in the analysis. The enhanced MARVEL 2 algorithm included a mode‐switching algorithm that automatically switches between VDD and ventricular only antibradycardia pacing (VVI)‐40 depending upon AVC status. Results: Forty‐two patients (58%) had persistent third degree AV block (AVB), 18 (25%) had 1:1 AVC, 5 (7%) had variable AVC status, and 8 (11%) had atrial arrhythmias. Among the 42 patients with persistent third degree AVB, the median ventricular pacing (VP) percentage was 99.9% compared to 0.2% among those with 1:1 AVC. As AVC status changed, the algorithm switched to VDD when the ventricular rate dropped less than 40 bpm. During atrial fibrillation (AF) with ventricular response greater than 40 bpm, VVI‐40 mode was maintained. No pauses longer than 1500 ms were observed. Frequent ventricular premature beats reduced the percentage of AV synchrony. During AF, the atrial signal was of low amplitude and there was infrequent sensing. Conclusion: The mode switching algorithm reduced VP in patients with 1:1 AVC and appropriately switched to VDD during AV block. No pacing safety issues were observed during arrhythmias. [ABSTRACT FROM AUTHOR]

Background: Coronary blood flow (CBF) is improved by cardiac resynchronization therapy (CRT) and impaired by right ventricular apical (RVA) pacing in patients with heart failure. However, the underlying mechanism remains unclear. Methods: Twenty-nine non-ischemic heart failure patients who responded to CRT underwent transthoracic echocardiography examination including both left anterior descending (LAD) CBF and tissue Doppler imaging in 3 pacing modes: intrinsic conduction, RVA pacing and biventricular (BiV) pacing. LAD velocity-temporal integral (LAD-VTI) and duration were measured. Systolic dyssynchrony was assessed with the standard deviation of a 12-left ventricular segmental model (Ts-SD). Results: BiV pacing improved while RVA pacing reduced CBF compared to intrinsic conduction (all p<0.05). Both Ts-SD and ventricular septal velocity deteriorated during RVA pacing but improved during BiV pacing (all p<0.05). When systolic dyssynchrony was induced, lower LAD-VTI (9.5±3.4 versus 12.7±5.1cm, p=0.001) and shorter LAD diastolic duration (483±92 versus 542±106ms, p=0.010) were detected than synchronous status. Systolic dyssynchrony was inversely related to septal velocity (r=−0.41), p<0.001 and LAD-VTI (r=−0.30, p=0.007), with the latter found to be moderately correlated to septal velocity (r=0.30, p=0.007). Conclusion: Regional LAD flow was improved in patients subjected to BiV but worsened in those treated with RVA pacing in non-ischemic heart failure CRT responders. Systolic dyssynchrony was more commonly observed in patients subjected to RVA pacing. Reduction of septal velocity with dyssynchrony may directly lead to reduced LAD flow. Improvement of septal velocity by CRT and hence LAD flow may be an important mechanism in determining the response to CRT. [ABSTRACT FROM AUTHOR]

Background: Deleterious effect on left ventricular (LV) function was observed with conventional right ventricular apical (RVA) pacing. Preliminary data suggested that biventricular pacing (BiV) may be superior to RVA pacing in patients with LV systolic dysfunction. However, the optimal pacing mode and site(s) for patients with normal LV systolic function remain controversial. Methods: The Pacing to Avoid Cardiac Enlargement (PACE) trial is a prospective, multicenter, randomized, double blinded, parallel, controlled study aiming to determine if BiV pacing is better than conventional RVA pacing in preserving LV systolic function and preventing remodeling in patients with LV ejection fraction (EF) 45% indicated for pacing. This study targets to recruit 200 patients from various centers in Asia, all of whom will receive BiV pacemaker implantation before being randomized to either atrial-based RVA or BiV pacing for 1 year. Their echocardiographic parameters including LV volumes, left ventricular ejection fraction (LVEF), and dyssynchrony index by tissue Doppler imaging, exercise capacity, quality of life assessment, neurohormone levels, and clinical events will be assessed before and after pacing. The primary endpoints are changes in LV end-systolic volume and LVEF 1 year after pacing. It is designed with 90% power to detect a 5% difference in the LVEF after 1 year of pacing. The enrollment began in 2006. It is expected to conclude at the end of 2008. Conclusion: The PACE trial will determine whether atrial-based BiV pacing can preserve LV systolic function and prevent LV adverse remodeling induced by conventional RVA pacing in patients with normal LV systolic function and standard pacing indication. [ABSTRACT FROM AUTHOR]

Background: Right ventricular apical (RVA) pacing is associated with adverse left ventricular (LV) remodeling and biventricular (BiV) pacing may prevent it although the mechanisms remain unclear. The current study aimed to assess the role of early pacing-induced systolic dyssynchrony (DYS) to predict adverse LV remodeling. Methods: Patients with standard pacing indications and normal LV ejection fraction were randomized either to BiV (n=89) or RVA pacing (n=88). Pacing-induced DYS, defined as the standard deviation of the time to peak systolic velocity (Dyssynchrony Index) >33ms in a 12-segmental model of LV, was measured by tissue Doppler echocardiography at 1month. Results: At 1month, 59 patients (33%) had DYS which was more prevalent in RVA than BiV pacing group (52% vs. 15%, χ2 =28.3, p<0.001), though Dyssynchrony Index was similar at baseline (30±14 vs. 26±11ms, p=0.06). At 12months, those developing DYS had significantly lower LV ejection fraction (55.1±9.7 vs. 62.2±7.9%, p<0.001) and larger LV end-systolic volume (35.3±14.3 vs. 27.0±10.4ml, p<0.001) when compared to those without DYS. Reduction of ejection fraction ≥5% occurred in 67% (39 out of 58) of patients with DYS, but only in 18% (21 out of 115) in those without DYS (χ2 =40.8, p<0.001). Both DYS at 1month (odds ratio [OR]: 4.725, p=0.001) and RVA pacing (OR: 3.427, p=0.009) were independent predictors for reduction of ejection fraction at 12months. Conclusion: Early pacing-induced DYS is a significant predictor of LV adverse remodeling and the observed benefit of BiV pacing may be related to the prevention of DYS. Clinical trial registration: Centre for Clinical Trials number, CUHK_CCT00037 (URL: http://www.cct.cuhk.edu.hk/Registry/publictrialrecord.aspx?trialid=CUHK_CCT00037). [ABSTRACT FROM AUTHOR]

Abstract: Background: This prospective study was to examine the impact of right ventricular apical (RVA) pacing on atrial remodeling and function. Methods and results: 103 patients (age 70±11years; 53 men) with preserved left ventricular (LV) ejection fraction (LVEF>45%) who received RVA pacing had Doppler echocardiography performed at baseline and after one year follow up. At one year follow up, left atrial (LA) volumes (pre-atrial contraction volume and the minimal volume) and their indexes were significantly increased with reduction in passive emptying fraction and total emptying fraction (all p<0.05). LA segmental tissue velocities – mean peak systolic (Sm-la), peak early diastolic (Em-la) and late diastolic (Am-la) – were also significantly reduced (all p<0.001). A reduction of Am-la>30% occurred in 24% of patients, and was more prevalent in patients with an elevation of LV filling pressure (E/e''>15) at one year (44.1% vs. 11.7%, χ2 =12.75, p<0.001) as well as those with a reduction of LVEF≥5% (34.0% vs. 14.3%, χ2 =5.140, p=0.023). By multivariate regression analysis, E/e''>15 at one year (odds ratio [OR] 5.213; 95% confidence interval [CI] 1.778–15.281) and reduction of LVEF≥5% (OR 3.181; 95% CI 1.045–9.686) were independent predictors of reduction of Am-la>30%. Conclusions: Chronic RVA pacing results in LA remodeling and reduced atrial function. This is related to elevated filling pressures and impairment of LV systolic function. [Copyright &y& Elsevier]