Dual Chamber And VVI Implantable Defibrillator Research Articles

Changes in hemodynamic parameters and atrial fibrillation risk in patients after permanent pacemaker implantation

Data on the development of left ventricular dysfunction after permanent pacemaker implantation are available. According to data from the DAVID (The Dual Chamber and VVI Implantable Defibrillator) study, it was shown that DDDR-paced patients had significantly more fatal events and HF deterioration cases requiring hospitalization. Similar were the results of the MOde Selection Trial (MOST), which poses serious questions to the cardiology community. For that reason it is important to understand how PPM implantation changes the hemodynamic parameters of the heart and what consequences this may have. On the one hand, asynchronous contraction of the paced heart and increase in AF risk with advancing age require active screening of asymptomatic paroxysms of tachyarrhythmias to promptly adjust therapy. On the other hand, minimizing the rate of ventricular pacing through proper programming of the devices should not be overlooked. Recently, various biomarkers have been validated to select high-risk patients in which the therapeutic strategy can be modulated on time.

Who Should Receive the Subcutaneous Implanted Defibrillator?

The evolution of implantable cardioverter defibrillator (ICD) technology for the past 3 decades has been nothing short of explosive, incorporating progressively transvenous leads, multizone programming, dual chamber antibradycardia pacing, antitachycardia pacing (ATP), sophisticated single- and dual-chamber discrimination algorithms, cardiac resynchronization therapy (CRT), and programmable options numbering into the thousands. As a consequence, ICDs have been used to treat patients with a variety of clinical needs, including those with a known history of ventricular tachycardia (VT), survivors of out of hospital cardiac arrest, patients with requirements for pacing or resynchronization with concomitant indications for an ICD, and patients who do not fit within these categories but are at risk for sudden cardiac death (SCD). Response by Rav Acha and Milan on p 1244 Typically, the efficacy of most cardiac therapies is assessed initially on the sickest patients or those at highest risk. Such was the case for the ICD that was initially approved only for patients who had survived cardiac arrest. These early systems had epicardial leads and no pacing capabilities. Subsequently, transvenous lead systems and other advances were made in ICD technology, as noted above. However, these devices were approved and used based on the demonstration of the ability to detect and to terminate VT and ventricular fibrillation (VF). In fact, more complex therapies are not always better for patient outcomes. The Dual Chamber and VVI Implantable Defibrillator (DAVID) trial showed that indiscriminate right ventricular pacing is associated with increased risk of heart failure hospitalization and death, and more recent analyses continue to question the overuse of dual chamber devices.1,2 Similarly, CRT may be associated with more heart failure hospitalization among patients without QRS prolongation.3 The landmark prospective randomized trials showed a mortality benefit of ICDs for both primary and secondary prevention of SCD. The early …

Hemodynamic Impact and Outcome of Permanent Pacemaker Implantation Following Transcatheter Aortic Valve Implantation

Transcatheter aortic valve implantation (TAVI) frequently requires postprocedural permanent pacemaker (PPM) implantation. We evaluated clinical and hemodynamic impact of PPM after TAVI. Clinical and echocardiographic data were retrospectively analyzed in 230 consecutive patients who underwent TAVI and echocardiography at baseline and after 6 months. Echocardiographic parameters included left ventricular ejection fraction (LVEF), left ventricular (LV) stroke volume, early mitral velocity/annulus velocity ratio (E/e'), right ventricular index of myocardial performance, systolic pulmonary artery pressure (SPAP), and aortic, mitral, and tricuspid regurgitation grades. Clinical outcomes included 2-year survival and cardiovascular and PPM-related event-free survival. The Medtronic CoreValve and Edwards Sapien prosthesis were used in 201 and 29 patients, respectively. PPM was required in 58 patients (25.4%). Two-year and event-free survival rates were similar between patients with and without PPM. At 6 months, patients with PPM demonstrated attenuated improvement in LVEF (-0.9 ± 8.7% vs 2.3 ± 10.8%, respectively, p = 0.03) and LV stroke volume (-2 ± 16 vs 4 ± 10 ml/m(2), respectively, p = 0.015), a trend toward smaller reduction in systolic pulmonary artery pressure (-1 ± 12 vs -6 ± 10 mm Hg, respectively, p = 0.09), and deterioration of right ventricular index of myocardial performance (-3 ± 17% vs 5 ± 26%, respectively, p = 0.05). The differences in post-TAVI aortic, mitral, and tricuspid regurgitation grades were insignificant. In conclusion, PPM implantation after TAVI is associated with reduced LVEF and impaired LV unloading. However, this unfavorable hemodynamic response does not affect the 2-year clinical outcome. The maintenance of clinical benefit appears to be driven by TAVI-related recovery of LV and right ventricular performance that mitigates unfavorable impact of PPM.

The Implantable Cardioverter-Defibrillator Minimalist

The implantable cardioverter-defibrillator (ICD) was devised to satisfy the unmet need for an effective, instantaneous therapy to prevent sudden cardiac death (SCD) due to ventricular fibrillation (VF) in at-risk, ambulatory patients. That therapy was a high-voltage electric shock delivered directly into the heart muscle. More than 3 decades later, shocks are still the defining operating characteristic of ICDs, and no other instantaneously effective therapy for VF exists. This elite status was clinched by large randomized clinical trials1,2 which demonstrated that ICDs improved mortality in patients with reduced left ventricular ejection fraction, regardless of pathogenesis or accompanying symptoms of heart failure (HF), by primary prevention of SCD due to ventricular tachyarrhythmia (VTA). Like bradycardia pacemakers for asystole, the ICD resides as a therapy genre of one, with no peer, and no competitor on the horizon. These sibling therapies for lethal heart rhythm disturbances will stand prominently among the greatest medical achievements of the 20th century. The ICD is a mature technology, and neither the technique nor the tools have changed much for several decades. Despite a certain evolutionary elegance of the operating system, the ICD is still a blunt instrument. Although it is true that some innovation has occurred, it is still a matter of a shock delivered by insulated metal conductors residing somewhere in direct proximity to the heart. No innovation beyond the fundamental of a timed shock for VF has proven to enhance mortality benefit. The basic design persists simply because no one can think of a suitable alternative and the self-satisfying aphorism that “shocks save lives.” Yet there is a growing intellectual dissatisfaction with the unintended consequences of this powerful, irreplaceable therapy. The stimulus for this self-inspection is an awareness of the very high morbidity risk overhead borne by the primary prevention patient, in particular, …

Heart rate, pacing, and outcome in the Dual Chamber and VVI Implantable Defibrillator (DAVID) trials

Slower heart rates are believed to confer a better prognosis in heart disease. The Dual Chamber and VVI Implantable Defibrillator (DAVID) Trial found that patients with ventricular dysfunction and isolated sinus bradycardia (rate <60 with normal PR interval) had an unusually low incidence of heart failure (HF) hospitalization and mortality when paced infrequently. The purpose of this study was to prospectively test our hypotheses that a similar benefit from bradycardia would be conferred in DAVID II as in DAVID but that this would be nullified by the faster heart rate achieved during atrial pacing in DAVID II. Effects of atrial versus minimal ventricular pacing on outcome in defibrillator recipients with isolated bradycardia in DAVID II were prospectively evaluated. Ninety-eight DAVID II patients with isolated bradycardia were similar to 502 patients without it but had less baseline HF. HF medications were used comparably in both groups at baseline and throughout the study. Overall, patients with isolated bradycardia were less likely to die or be hospitalized for HF than others (12.2% vs. 26%; P = .01). There was no evidence that atrial pacing diminished this association. Adjusted for covariates, particularly baseline HF and its treatment, isolated bradycardia patients had substantially reduced risk for HF/death (P = .018) with or without atrial pacing (relative risk 0.47 and 0.71, respectively). Isolated bradycardia identifies patients at lower risk for HF and mortality, an association that is not necessarily negated by accelerating heart rate with atrial pacing. This apparent conundrum challenges the use of heart rate as a therapeutic target in patients with ventricular dysfunction. http://www.clinicaltrials.gov NCT00187187.

The DAVID (Dual Chamber and VVI Implantable Defibrillator) II Trial

The purpose of this study was to determine whether atrial pacing is a safe alternative to minimal (backup-only) ventricular pacing in defibrillator recipients with impaired ventricular function. The DAVID (Dual Chamber and VVI Implantable Defibrillator) trial demonstrated that dual chamber rate responsive pacing as compared with ventricular backup-only pacing worsens the combined end point of mortality and heart failure hospitalization. Although altered ventricular activation from right ventricular pacing was presumed to be the likely cause for these maladaptive effects, this supposition is unproven. In all, 600 patients with impaired ventricular function from 29 North American sites, who required an implanted defibrillator for primary or secondary prevention, with no clinical indication for pacing, were randomly assigned to atrial pacing (at 70 beats/min) versus minimal ventricular pacing (at 40 beats/min) and followed up for a mean of 2.7 years. There were no significant differences between pacing arms in patients' baseline characteristics, use of heart failure medications, and combined primary end point of time to death or heart failure hospitalization during follow-up, with an overall incidence of 11.1%, 16.9%, and 24.6% at 1, 2, and 3 years, respectively. Similarly, the incidence of atrial fibrillation, syncope, appropriate or inappropriate shocks, and quality of life measures did not significantly differ between treatment groups. The effect of atrial pacing on event-free survival and quality of life was not substantially worse than, and was likely equivalent to, backup-only ventricular pacing. Atrial pacing may be considered a "safe alternative" when pacing is desired in defibrillator recipients, but affords no clear advantage or disadvantage over a ventricular pacing mode that minimizes pacing altogether. (Dual Chamber and VVI Implantable Defibrillator [DAVID] Trial II; NCT00187187).

Effect of Pacing for Soft Indications on Mortality and Heart Failure in the Dual Chamber and VVI Implantable Defibrillator (DAVID) Trial

The dual chamber and VVI implantable defibrillator (DAVID) trial demonstrated that dual chamber (DDDR) pacing in defibrillator candidates with impaired ventricular function and no established indication for pacing resulted in worsened congestive heart failure (CHF) or death. Many patients had abnormalities for which pacing is often advocated to improve the management of ventricular dysfunction. Evaluate the impact and interaction of nonessential but potentially justifiable reasons to pace ("soft indications"), together with pacing mode, on outcome. DAVID patients were stratified by those with and without "soft indications" for pacing (rate < 60 beats/min or first-degree atrioventricular block) (n = 169; n = 335, respectively). This analysis also stratified patients by normal and abnormal QRS conduction (QRS >or= 110 ms), who were previously found to be affected differently by DDDR pacing. Groups were analyzed according to the combined endpoint of mortality or CHF hospitalization. When assigned to treatment that promoted pacing (DDDR), the incidence of death or CHF tended to be higher in patient subgroups with and without "soft indications," consistent with results from DAVID. Patients with, compared to those without, these abnormalities neither benefited nor were less adversely affected when actively paced. The presence or absence of "soft indications" also provided no additional explanation for the differing outcomes in patient cohorts with and without abnormal QRS conduction. Sinus bradycardia or first-degree atrioventricular block did not ameliorate the poor outcomes associated with dual-chamber compared with VVI pacing, and do not justify conventional dual-chamber pacing in defibrillator recipients with ventricular dysfunction.

Impact of Atrial Pacing on Quality of Life in the Dual Chamber and VVI Implantable Defibrillator (DAVID) II Trial

Objective: The Dual Chamber and VVI Implantable Defibrillator (DAVID) Trial found that dual-chamber pacing (DDDR-70) at rates of 70 beats/min or faster in patients with standard indications for an implantable defibrillator but no indication for pacing increased the risk of death or hospitalization for congestive heart failure (CHF). It was not possible to determine from the DAVID trial whether this harm resulted from a faster heart rate from pacing or specifically from the location in the heart where pacing was conducted.

Response to Abraham

More than 4000 patients have been evaluated in randomized controlled trials of cardiac resynchronization therapy (CRT). These studies have demonstrated that CRT with or without an implantable cardioverter-defibrillator (ICD) consistently improves quality of life, functional status, exercise capacity, and cardiac structure and function and reduces morbidity and mortality in heart failure patients with ventricular dyssynchrony. The magnitude of benefit seen with CRT is comparable to or exceeds that seen with evidence-based drug therapies for heart failure but occurs in patients who are already receiving such medications. Thus, CRT has been added to the list of evidence-based therapies that make heart failure patients feel better and live longer (the Table). Consequently, a strong ethical mandate exists for the use of CRT in heart failure. This mandate is reflected in our current practice guidelines for the management of chronic heart failure, which state that all eligible patients should receive CRT unless contraindicated.1,2 End of debate! CRT should be a routine part of any evidence-based treatment regimen for heart failure. View this table: Major Benefits of Evidence-Based Heart Failure Therapies Of course, things are never quite so simple, so let us take a look at the evidence supporting this clinical mandate for CRT and address patient selection, some of the limitations of CRT, and some of the unanswered questions about the use of CRT in heart failure. None of this discussion will lessen the role of CRT in the treatment of heart failure; rather, it will guide the selection of appropriate patients and speculate on the future application of CRT to an even broader group of heart failure patients. Response by Greenberg and Mehra p 2698 Approximately one third of patients with systolic heart failure exhibit ventricular dyssynchrony, defined as a QRS duration >120 ms on the surface ECG.3,4 Ventricular dyssynchrony produces suboptimal ventricular …

Full Length Article

The purpose of this study was to determine whether QRS duration or morphology increased the risk of adverse outcome in the DAVID (Dual Chamber and VVI Implantable Defibrillator) trial. The DAVID trial found an increased risk of the combined end point of death and new or worsening congestive heart failure (CHF) in defibrillator recipients who were paced DDDR-70 versus VVI-40. We analyzed the combined end point in patients with abnormal QRS duration (AbQRS) (≥110 ms) compared with those with normal QRS duration (NQRS) (<110 ms). The QRS data were available for 496 of the 506 patients enrolled in the trial, including 223 patients with NQRS (45%) and 273 patients with AbQRS (55%). In patients in whom defibrillators were programmed to pace infrequently (VVI-40), having an NQRS or AbQRS was not an indicator of increased risk of adverse outcome. However, among patients in whom defibrillators were programmed in a manner that promoted more frequent ventricular pacing (DDDR-70), there was a significant adverse interaction with AbQRS; this combination was independently associated with a higher risk for developing CHF or death (p = 0.017). Although patients with AbQRS tended to have other risk factors associated with poor outcome, the interaction of QRS duration with ventricular pacing (DDDR-70) independently contributed to a worse outcome and therefore, was a marker of patients in whom such treatment may be harmful. This should not imply that right ventricular pacing in NQRS patients is safe but rather that pacing in the context of an AbQRS is probably best avoided.

Abnormal Conduction Increases Risk of Adverse Outcomes From Right Ventricular Pacing

The purpose of this study was to determine whether QRS duration or morphology increased the risk of adverse outcome in the DAVID (Dual Chamber and VVI Implantable Defibrillator) trial. The DAVID trial found an increased risk of the combined end point of death and new or worsening congestive heart failure (CHF) in defibrillator recipients who were paced DDDR-70 versus VVI-40. We analyzed the combined end point in patients with abnormal QRS duration (AbQRS) (> or =110 ms) compared with those with normal QRS duration (NQRS) (<110 ms). The QRS data were available for 496 of the 506 patients enrolled in the trial, including 223 patients with NQRS (45%) and 273 patients with AbQRS (55%). In patients in whom defibrillators were programmed to pace infrequently (VVI-40), having an NQRS or AbQRS was not an indicator of increased risk of adverse outcome. However, among patients in whom defibrillators were programmed in a manner that promoted more frequent ventricular pacing (DDDR-70), there was a significant adverse interaction with AbQRS; this combination was independently associated with a higher risk for developing CHF or death (p = 0.017). Although patients with AbQRS tended to have other risk factors associated with poor outcome, the interaction of QRS duration with ventricular pacing (DDDR-70) independently contributed to a worse outcome and therefore, was a marker of patients in whom such treatment may be harmful. This should not imply that right ventricular pacing in NQRS patients is safe but rather that pacing in the context of an AbQRS is probably best avoided.

Harmful effects of long-term right ventricular pacing

Much evidence has emerged recently about the harmful effects of chronic right ventricular (RV) pacing (mostly apical) on left ventricular (LV) function1-13. The left ventricle (LV) normally contracts rapidly and synchronously with little variation in the onset of electrical and mechanical activation throughout the wall. The pathophysiologic consequences of RV pacing are similar to those of left bundle branch block (LBBB): asynchronous (and delayed) electrical and mechanical LV activation. Endocardial catheter mapping studies have unequivocally demonstrated that RV pacing mimics the endocardial activation patterns of LBBB14. It is therefore not surprising that chronic RV pacing imposes basically the same chronic adverse effects as chronic LBBB on LV hemodynamics and function15. Longterm RV pacing like chronic LBBB produces structural changes resulting in chronic systolic and diastolic LV dysfunction that contribute to reduced LV pumping function on a long-term basis. The changes include paradoxical septal wall motion, delayed LV lateral wall contraction, reduced LV pressure, mitral regurgitation, increased left atrial diameters, reduced diastolic filling times, and distorted LV geometry. These abnormalities correlate with those documented in experimental animals subjected to long-term RV pacing such as adverse cellular changes with myofibrillar disarray, asymmetric myocardial hypertrophy and LV dilatation as well as biochemical abnormalities16-20. The Dual Chamber and VVI Implantable Defibrillator (DAVID) trial

Section 7: Heart Failure in Patients With Left Ventricular Systolic Dysfunction

Section 7: Heart Failure in Patients With Left Ventricular Systolic Dysfunction

Percent right ventricular pacing predicts outcomes in the DAVID trial

The Dual-Chamber and VVI Implantable Defibrillator (DAVID) trial demonstrated a worse outcome in patients with implantable cardioverter-defibrillators (ICDs) programmed to DDDR at 70 bpm compared with patients who had ICDs programmed to VVI backup pacing at 40 bpm. Pacing was more frequent in the DDDR group. The purpose of this study was to determine whether right ventricular pacing (RV) is an independent predictor of outcome in the DAVID trial. We evaluated the relationship of percent RV pacing to the composite endpoint of death or hospitalization for congestive heart failure. Patients who had a 3-month follow-up and who had not yet reached an endpoint were included in the study. Using Cox regression analysis (VVI group N = 195; DDDR group N = 185), we examined multiple factors, including percent RV pacing at 3-month follow-up, that might be associated with adverse outcomes. Percent RV pacing as a continuous variable was correlated with the primary endpoint. As a dichotomous variable, the best separation for predicting endpoints occurred with DDDR RV pacing > 40% vs DDDR RV pacing < or = 40% (P = .025). Patients with DDDR RV pacing < or = 40% had similar or better outcomes to the VVI backup group (P = .07). Correction for baseline variables predictive of the composite outcome in the (nonpaced) VVI group (use of nitrates, increased heart rate, and increased age) did not change the findings for RV pacing (P = .008). In contrast, atrial pacing was not predictive of worse outcomes. These results suggest, but do not prove, a causal relationship between frequent RV pacing and adverse outcomes in patients with left ventricular ejection fraction < or = 40%.

A Comparison of the AVID and DAVID Trials of Implantable Defibrillators

We compared 2 studies of implantable cardiac defibrillators (ICDs) to determine the effects of device mode on outcomes. The Antiarrhythmics Versus Implantable Defibrillators (AVID) trial (1993 to 1997) demonstrated improved survival with the ICD compared with antiarrhythmic drug therapy. The Dual-chamber And VVI Implantable Defibrillator (DAVID) trial (2000 to 2002) showed that VVI pacing at 40 beats/min in patients with ICDs reduced the combined end point of death and hospitalization for congestive heart failure compared with DDDR pacing at 70 beats/min. Patients in the AVID trial (631 of 1,016) and the DAVID trial (221 of 506) meeting common inclusion and all exclusion criteria were studied. The major end points were the time to death, and the composite end point of time to death or hospitalization for congestive heart failure. Patients in the AVID and DAVID trials were similar, but more AVID patients had coronary artery disease (p = 0.04), history of myocardial infarction (p = 0.005), and previous ventricular arrhythmias (p = 0.03). DAVID patients underwent more previous revascularization procedures (coronary artery bypass surgery, p = 0.03; percutaneous coronary intervention, p = 0.001), and were more often taking beta-blocking drugs at hospital discharge (p <0.001). The backup VVI ICD groups in both studies had similar outcomes (p = 0.4), even when corrected for the previous demographic differences. The time-to- composite end point was similar in AVID patients treated with antiarrhythmic drugs and DAVID patients treated with DDDR ICDs (p = 0.6). Despite improved pharmacologic therapy and revascularization, outcomes have not improved with backup VVI pacing ICDs. If DDDR ICDs had been used in the AVID trial, benefit from ICDs for patients with serious ventricular arrhythmias could have been missed.

1053-213 The predictive value of electrophysiologic testing: subgroup analysis in the dual chamber and VVI implantable defibrillator (DAVID) trial

1053-213 The predictive value of electrophysiologic testing: subgroup analysis in the dual chamber and VVI implantable defibrillator (DAVID) trial

Comparison of perception of health status by physicians, nurses, and patients in the Dual-chamber And VVI Implantable Defibrillator (DAVID) trial

Previous studies have shown a poor correlation between health and quality-of-life assessments by patients, physicians, and nurses. Some have argued that patients are treated impersonally in clinical trials. Because one would expect that patient care would be compromised if this were the case, we used the Dual-chamber And VVI Implantable Defibrillator (DAVID) clinical trial setting to see if these assertions truly reflect the assessments of quality of life by health care professionals. Physicians, nurses, and patients in the DAVID trial had concordant assessments of the patients' perception of health status. The findings dispel assertions that patient concerns are not reliably assessed.

Dual-chamber pacing or ventricular backup pacing in patients with an implantable defibrillator. The dual chamber and VVI implantable defibrillator (DAVID) trial

Dual-chamber pacing or ventricular backup pacing in patients with an implantable defibrillator. The dual chamber and VVI implantable defibrillator (DAVID) trial

Should all patients receive dual chamber pacing ICDs? The rationale for the DAVID trial

All of the prospective multicenter trials that support the use of implantable defibrillators have used single chamber pacemakers/implantable cardiovertor defibrillators (ICDs). Despite the significantly increased cost of dual chamber pacemaker/ICD devices and the lack of outcome data, these devices accounted for approximately two-thirds of the ICDs implanted in the United States during the 12 months ending April 2001. Dual chamber pacemaker trials have not provided data that would support this trend, but the high incidence of atrial fibrillation, bradycardia, and congestive heart failure, as comorbid conditions, suggest that the situation could be different in the defibrillator patient population. The DAVID (Dual Chamber and VVI Implantable Defibrillator) trial is designed to measure the incremental benefit of dual chamber pacemaker/ICDs.