A Prospective Randomized Evaluation of VV Delay Optimization in CRT-D Recipients: Echocardiographic Observations from the RHYTHM II ICD Study

Background: All current cardiac resynchronization therapy (CRT) devices allow the programming of the atrioventricular (AV/PV) delays and the sequential stimulation of the ventricles via the inter ventricular (VV) delay.
Aim: This post hoc analysis of the RHYTHM II study was conducted to compare the reverse remodeling associated with VV delay optimization in patients randomly assigned to simultaneous (SIM) biventricular stimulation versus patients assigned to optimized VV delay programming (OPT) (1:3 randomization scheme).
Methods: The analysis included 14 patients assigned to the SIM group and 34 patients to the OPT group who completed the 6-month follow-up period with paired echocardiographic recordings.
Results: In both study groups, changes consistent with left ventricular (LV) remodeling were observed between baseline and 6 months, with significant improvements in LV function and decrease in LV dimensions. In the OPT group, there was also a decrease in left atrial diameter and mitral valve closure to opening time. At 6 months, the overall proportion of echocardiographic responders (≥10% decrease in LV end-systolic volume or ≥5% absolute increase in LV ejection fraction) was similar in both groups. The optimal AV/VV delays, evaluated by maximization of LV outflow tract velocity time integral, changed over time.
Conclusions: Ventriculo-ventricular delay optimization was associated with better immediate hemodynamic function than simultaneous biventricular stimulation, though did not promote additional reverse remodeling at 6 months and did not increase the proportion of echocardiographic responders to CRT. Optimization of both the AV and VV intervals was patient-specific and optimal values changed over time.     

Outcomes of Elderly Recipients of Implantable Cardioverter Defibrillators

Aims of the Study: To examine the patterns of use, complication rates, and survival in elderly recipients of implantable cardioverter defibrillators (ICD).
Methods and Results: We followed 500 consecutive patients included in the Marburg Defibrillator database for 48 ± 39 months. There were 40 patients (8%) ≥75 and 460 (92%) <75 years of age at the time of implant. The 5-year Kaplan-Meier estimate for appropriate treatment of VT or VF by ICD was 49% among patients <75- versus 57% among patients ≥75-years-old (P = 0.17). The 5-year sudden death rate was similarly low in both groups of patients (2% versus 3%). The 5-year overall mortality rate was significantly higher in patients ≥75 than in patients <75 years of age (55% versus 21%, P = 0.001), due to a higher mortality from heart failure (HF). All procedure-related, lead-related, and pulse generator-related complications were similar in both patient groups (23% versus 25%).
Conclusions: ICD therapy was equally effective in patients ≥75 and patients <75 years of age in the prevention of sudden cardiac death. While the complication rates were similar in both age groups, the long-term mortality was considerably higher in elderly patients, due to a higher mortality from HF. The current ICD therapy guidelines appear applicable to elderly patients who are otherwise medically stable and without advanced HF.     

Similar Long-Term Benefits Conferred by Apical Versus Mid-Septal Implantation of the Right Ventricular Lead in Recipients of Cardiac Resynchronization Therapy Systems

Introduction: The benefits conferred by cardiac resynchronization therapy (CRT) are markedly influenced by the left ventricular (LV) lead placement. Little is known regarding the optimal right ventricular (RV) stimulation site.
Study Objective: To compare the long-term outcomes of CRT in patients with RV leads placed in the mid-septal region versus the apex.
Methods and Results: This nonrandomized, observational study included 117 patients with standard indications for CRT. The LV lead was implanted on the postero-lateral or lateral LV wall, while the RV lead was implanted at the apex (n = 82) or in the mid-septum (n = 35). Both groups were similar with respect to baseline clinical, demographic, and echocardiographic characteristics. After 12 months of CRT, the rates of clinical response to CRT were similar in both groups (63% vs. 66%), and similar degrees of reverse LV remodeling and LV resynchronization were observed on echocardiography and color tissue Doppler imaging. A ≥30% relative increase in LV ejection fraction (EF) occurred in 76% of patients in the RV apex group, versus 49% of patients in the RV mid-septum group (P = 0.05). A ≥45% left ventricular ejection fraction (LVEF) was measured at 12 months in 40% of patients in the RV apex group, versus 31% in the RV mid-septum group (ns).
Conclusions: RV mid-septal stimulation was not associated with a higher rate of response to CRT or greater improvement in LV function compared to RV apical stimulation.     

How,Why, and When May Atrial Defibrillation Find a Specific Role in Implantable Devices? A Clinical Viewpoint

This viewpoint article discusses the potential for incorporation of atrial defibrillation capabilities in modern multi-chamber devices. In the late 1990s, the possibility of using shock-only therapy to treat selected patients with recurrent atrial fibrillation (AF) was explored in the context of the stand-alone atrial defibrillator. The failure of this strategy can be attributed to the technical limitations of the stand-alone device, low tolerance of atrial shocks, difficulties in patient selection, a lack of predictive knowledge about the evolution of AF, and, last but not least, commercial considerations. An open question is how atrial defibrillation capability may now assume a specific new role in devices implanted for sudden death prevention or cardiac resynchronization. For patients who already have indications for implantable devices, device-based atrial defibrillation appears attractive as a "backup" option for managing AF when preventive pharmacological/electrical measures fail. This and several other personalized hybrid therapeutic approaches await exploration, though assessment of their efficacy is methodologically challenging. Achievement of acceptance by patients is an essential premise for any updated atrial defibrillation strategy. Strategies that are being investigated to improve patient tolerance include waveform shaping, pharmacologic modulation of pain, and patient-activated defibrillation (patients might also perceive the problem of discomfort somewhat differently in the context of a backup therapy). The economic impact of implementing atrial defibrillation features in available devices is progressively decreasing, and financial feasibility need not be a major issue. Future studies should examine clinically relevant outcomes and not be limited (as occurred with stand-alone defibrillators) to technical or other soft endpoints.     

Impact of mitral regurgitation on the outcome of patients treated with CRT-D: data from the InSync ICD Italian Registry

Background: We assessed the influence of clinically significant mitral regurgitation (MR) on clinical‐echocardiographic response and outcome in heart failure (HF) patients treated with a biventricular defibrillator (cardiac resynchronization therapy defibrillator [CRT‐D]). Methods and Results: A total of 659 HF patients underwent successful implantation of CRT‐D and were enrolled in a multicenter prospective registry (median follow‐up of 15 months). Following baseline echocardiographic evaluation, patients were stratified into two groups according to the severity of MR: 232 patients with more than mild MR (Group MR+: grade 2, 3, and 4 MR) versus 427 patients with mild (grade 1) or no functional MR (Group MR?). On 6‐ and 12‐month echocardiographic evaluation, MR was seen to have improved in the vast majority of MR+ patients, while it remained unchanged in most MR? patients. On 12‐month follow‐up evaluation, a comparable response to CRT was observed in the two groups, in terms of the extent of left ventricular reverse remodeling and combined clinical and echocardiographic response. During long‐term follow‐up, event‐free survival did not differ between MR+ and MR? patients, even when subpopulations of patients with ischemic heart disease and with dilated cardiomyopathy were analyzed separately. On multivariate analysis, the only independent predictor of death from any cause was the lack of β‐blocker use. Conclusions: This observational analysis supports the use of CRT‐D in HF patients with clinically significant MR; MR had no major influence on patient outcome. (PACE 2012; 35:146–154)     

Utilization of Defibrillators and Resynchronization Therapy at the Time of Evaluation at a Heart Failure and Cardiac Transplantation Center

Background: Internal cardioverter defibrillators (ICDs) and cardiac resynchronization therapy (CRT) reduce mortality, but are underutilized in routine clinical practice. The use of these devices in patients at the time of an initial evaluation at an advanced heart failure and cardiac transplantation center is unknown. Methods: We retrospectively analyzed consecutive patients who were enrolled in a database examining parameters of cardiopulmonary exercise testing in chronic heart failure (CHF) patients at the time of an initial outpatient evaluation at a tertiary care center. Rates of ICD and CRT use in eligible patients were determined. Results: Two hundred two patients had an average age of 54 ± 13 years and an average peak oxygen consumption (pVO₂) of 12.5 ± 4.5 mL/kg/min. Of 97 patients eligible for an ICD only, 57% had an ICD at the time of evaluation. Sixty‐four percent of ICD‐eligible male patients had an ICD compared to 36% of ICD‐eligible female patients (P = 0.015). Of 105 patients meeting criteria for CRT, 54% had a CRT device. There was no difference between CRT use in eligible male and female patients. Conclusions: ICDs and CRT are underutilized in patients with severe CHF at the time of evaluation at a tertiary care center despite young age, objective functional limitation, and active consideration for advanced CHF therapies. Female patients have lower rates of ICD use than male patients. (PACE 2010; 988–993)     

Long-Term Effectiveness of Dual Site Left Ventricular Cardiac Resynchronization Therapy in a Patient with Congestive Heart Failure

This article describes a case of cardiac resynchronization therapy (CRT) performed with dual site left ventricular pacing. The main clinical and functional long-term results are in agreement with the most recent data regarding traditional CRT. Furthermore, this innovative pacing modality allowed optimal inter- and intraventricular resynchronization. (PACE 2004; 27[Pt. I]:805–807)     

Device therapy in Chagas disease heart failure

Chagas disease is the principal cause of chronic heart failure in areas where the disease is endemic. The medical treatment is the same recommended for non-Chagas disease patients. There is no evidence-based medicine support for device therapy in Chagas disease heart failure. Cardiac resynchronization therapy is recommended for Chagas disease heart failure patients with intraventricular conduction disturbances, mainly for those with left bundle branch block, and in advanced congestive heart failure refractory to targeted medical treatment, although this therapy is still polemic in Chagas disease heart failure. Implantable cardioverter–defibrillator (ICD) therapy is indicated to Chagas disease patients with left ventricular ejection fraction <30% for primary prevention of sudden cardiac death. ICD therapy is offered to patients for secondary prevention of sudden cardiac death. Patients with moderate left ventricular dysfunction and inducible arrhythmia at electrophysiological testing should receive ICD therapy.     

Long-Term Variations in Optimal Programming of Cardiac Resynchronization Therapy Devices

The optimal follow-up and long-term programming of cardiac resynchronization therapy (CRT) devices are uncertain. The aim of this study was to quantify the temporal variations in programming parameters to optimize the follow-up of these devices. Before, during, and at specified intervals over 9 months after implant, 40 recipients of CRT devices were studied. At each visit, the patients were tested with a fixed sequence of stimulation parameters during echocardiographic and electrocardiographic (ECG) recordings. The optimal AV delay and inter-ventricular delays (V-V) were determined according to echocardiographic criteria. The echocardiographic data were, in turn, compared with the ECG recordings. Among the 40 patients, the optimal stimulation parameters remained unchanged throughout the follow-up in only three patients. In 18 patients, adjustments were required at each follow-up sessions. There was a trend toward reduction in the left ventricular (LV) predominance of the optimal V-V delay and an increase in the AV delay during follow-up. The mean optimal V-V delay at implant was 22 ms (−12 to +32 ms) with the LV activated first, versus 12 ms (−16 to +32 ms) at 9 months. The mean AV delay at implant was 115 ms versus 137 ms at 9 months. Individual changes could not be accurately predicted. The optimal stimulation parameters for CRT vary over time. Detailed, regular reevaluations, and reprogramming of optimal parameters may be appropriate.     

Comparison of ICD shock rates in Japanese and non‐Japanese patients in the PainFree SST study

Background

The PainFree Smart Shock Technology (SST) study showed a low implantable cardioverter‐defibrillator (ICD) inappropriate shock rate. However, the majority of patients were from Western countries with patient characteristics different from those in Japan. ICD shock rates using the novel SST algorithms in Japanese patients are still unknown.

Methods

All 2,770 patients in the PainFree SST study (Japan [JPN]: N = 181, other geographies [OJPN]: N = 2,589) were included in this analysis.

Results

Japanese patients had higher average left ventricular ejection fraction (P < 0.0001), higher prevalence of secondary prevention indications (P < 0.0001), nonischemic cardiomyopathy (P < 0.0001), and permanent atrial fibrillation (P < 0.0001). The appropriate shock rate at 12 months was not different between JPN and OJPN: 6.4% and 6.3%, respectively (P = 0.95). The inappropriate shock rate at 12 months was significantly higher in Japanese patients (2.9% vs 1.7%, P = 0.017). However, after propensity score matching to adjust for the difference in baseline characteristics, the difference in inappropriate shock rate was not statistically significant (P = 0.51).

Conclusions

There was no difference in the appropriate shock rate between Japan and other geographies. The inappropriate shock rate in Japan was low, although it was slightly higher compared to other geographies due to baseline characteristics, including a higher prevalence of permanent AF. There was not a statistically significant difference after adjusting for baseline characteristics.

     

Response to Cardiac Resynchronization Therapy in Patients with Heart Failure and Renal Insufficiency

Background: Renal insufficiency (RI) adversely impacts prognosis in heart failure (HF) patients, partly because renal and cardiac dysfunction are intertwined, yet few cardiac resynchronization therapy (CRT) studies have examined patients with moderate‐to‐severe RI. Methods: We analyzed 787 CRT‐defibrillator (CRT‐D) recipients with a glomerular filtration rate (GFR) measured prior to implant. Patients were grouped by GFR (in mL/min/1.73 m²): ≥60 (n = 376), 30–59 (n = 347), and <30 (n = 64). Overall survival, changes in left ventricular (LV) ejection fraction and LV end‐systolic diameter, and GFR change at 3–6 months were compared among CRT‐D groups and with a control cohort (n = 88), also stratified by GFR, in whom LV lead implant was unsuccessful and a standard defibrillator (SD) was placed. All patients met clinical criteria for CRT‐D. Results: Among CRT‐D recipients, overall survival improved incrementally with higher baseline GFR (for each 10 mL/min/1.73 m² increase, corrected hazard ratio [HR] 1.21, 95% confidence interval [CI] 1.13–1.30, P < 0.0001). Survival among SD and CRT‐D patients within GFR < 30 and GFR ≥ 60 groups was similar, whereas CRT‐D recipients with GFR 30–59 had significantly better survival compared to SD counterparts (HR 2.23, 95% CI 1.34–3.70; P = 0.002). This survival benefit was associated with improved renal and cardiac function. CRT recipients with GFR ≥ 60 derived significant echocardiographic benefit but experienced a GFR decline, whereas those with GFR < 30 had no echocardiographic benefit but did improve GFR. Conclusions: CRT may provide the largest survival benefit in HF patients with moderate RI, perhaps by improving GFR and LV function. Severe baseline RI predicts poor survival and limited echocardiographic improvement despite a modest GFR increase, such that CRT may not benefit those with GFR < 30 mL/min/1.73 m². CRT recipients with normal renal function derive echocardiographic benefit but no overall survival advantage. (PACE 2010; 850–859)     

Utilization of intracardiac echocardiography to access the coronary sinus for left ventricular lead placement

This is a presentation of a case series of 10 consecutive patients undergoing implantation of cardiac resynchronization therapy defibrillator (CRT-D). Intracardiac echocardiography (ICE) is utilized to gain access to the coronary sinus. The method used is detailed with a brief discussion of observations gained from this early experience.     

In the wireless era: leadless pacing

Cardiac pacemakers have been the standard therapy for patients with bradyarrhythmias for several decades. The pacing lead is an integral part of the system that serves as a conduit for the delivery of energy pulses to stimulate the myocardium. However, it is also an Achilles tendon that directly causes most device complications both acutely during implant and chronically years afterwards. Both durability and optimization of the stimulation site are important areas of improvement for manufacturers and implanters. Elimination of the pacing lead and the utilization of other means for energy transfer is the only way to avoid lead complications and allow a better choice of stimulation site. Leadless pacing with ultrasound-mediated energy has been demonstrated in animals and humans in acute studies. This has aroused intense interest in the field of cardiac pacing. With concerted effort from the profession and the industry, leadless pacing may indeed become a realizable concept.