Factors associated with temporary pacing insertion in patients with inferior ST-segment elevation myocardial infarction

Background

High-degree atrioventricular block (HAVB) is a prognostic factor for survival in patients with inferior ST-segment elevation myocardial infarction (STEMI). However, there is little information about factors associated with temporary pacing (TP). The aim of this study was to find factors associated with TP in patients with inferior STEMI.

Methods

We included 232 inferior STEMI patients, and divided those into the TP group (n = 46) and the non-TP group (n = 186). Factors associated with TP were retrospectively investigated using multivariate logistic regression model.

Results

The incidence of right ventricular (RV) infarction was significantly higher in the TP group (19.6%) than in the non-TP group (7.5%) (p = 0.024), but the incidence of in-hospital death was similar between the 2 groups (4.3% vs. 4.8%, p = 1.000). Long-term major adverse cardiovascular events (MACE), which were defined as a composite of all-cause death, non-fatal myocardial infarction (MI), target vessel revascularization (TVR) and readmission for heart failure, were not different between the 2 groups (p = 0.100). In the multivariate logistic regression analysis, statin at admission [odds ratio (OR) 0.230, 95% confidence interval (CI) 0.062–0.860, p = 0.029], HAVB at admission (OR 9.950, 95% CI 4.099–24.152, p<0.001), and TIMI-thrombus grade ≥3 (OR 10.762, 95% CI 1.385–83.635, p = 0.023) were significantly associated with TP.

Conclusion

Statin at admission, HAVB at admission, and TIMI-thrombus grade ≥3 were associated with TP in patients with inferior STEMI. Although the patients with TP had the higher incidence of RV infarction, the incidence of in-hospital death and long-term MACE was not different between patients with TP and those without.

Outcomes of TTVI in Patients With Pacemaker or Defibrillator Leads: Data From the TriValve Registry

OBJECTIVES

The interference of a transtricuspid cardiac implantable electronic device (CIED) lead with tricuspid valve function may contribute to the mechanism of tricuspid regurgitation (TR) and poses specific therapeutic challenges during transcatheter tricuspid valve intervention (TTVI). Feasibility and efficacy of TTVI in presence of a CIED is unclear.

BACKGROUND

Feasibility of TTVI in presence of a CIED lead has never been proven on a large basis.

METHODS

The study population consisted of 470 patients with severe symptomatic TR from the TriValve (Transcatheter Tricuspid Valve Therapies) registry who underwent TTVI at 21 centers between 2015 and 2018. The association of CIED and outcomes were assessed.

RESULTS

Pre-procedural CIED was present in 121 of 470 (25.7%) patients. The most frequent location of the CIED lead was the posteroseptal commissure (44.0%). As compared with patients without a transvalvular lead (no-CIED group), patients having a tricuspid lead (CIED group) were more symptomatic (New York Heart Association functional class III to IV in 95.9% vs. 92.3%; p = 0.02) and more frequently had previous episodes of right heart failure (87.8% vs. 69.0%; p = 0.002). No-CIED patients had more severe TR (effective regurgitant orifice area 0.7 ± 0.6 cm² vs. 0.6 ± 0.3 cm²; p = 0.02), but significantly better right ventricular function (tricuspid annular plane systolic excursion = 16.7 ± 5.0 mm vs. 15.9 ± 4.0 mm; p = 0.04). Overall, 373 patients (79%) were treated with the MitraClip (Abbott Vascular, Santa Clara, California) (106 [87.0%] in the CIED group). Among them, 154 (33%) patients had concomitant transcatheter mitral repair (55 [46.0%] in the CIED group, all MitraClip). Procedural success was achieved in 80.0% of no-CIED patients and in 78.6% of CIED patients (p = 0.74), with an in-hospital mortality of 2.9% and 3.7%, respectively (p = 0.70). At 30 days, residual TR ≤2+ was observed in 70.8% of no-CIED and in 73.7% of CIED patients (p = 0.6). Symptomatic improvement was observed in both groups (NYHA functional class I to II at 30 days: 66.0% vs. 65.0%; p = 0.30). Survival at 12 months was 80.7 ± 3.0% in the no-CIED patients and 73.6 ± 5.0% in the CIED patients (p = 0.30).

CONCLUSIONS

TTVI is feasible in selected patients with CIED leads and acute procedural success and short-term clinical outcomes are comparable to those observed in patients without a transtricuspid lead.

Prognosis after pacemaker implantation in extreme elderly

AIMS

Significant comorbidities may limit the potential benefit of pacemaker (PM) implantation in extreme elderly. A short-term mortality risk prediction score, able to identify high-risk patients, may be a useful tool in this population.

METHODS AND RESULTS

We retrospectively analyzed 538 patients aged >80 years at the time of implant who underwent PM implantation. Kaplan-Meier survival and multivariable Cox regression analyses were performed to identify patient, procedural or complication variables predictive of death. The ACP (Aging in Cardiac Pacing) Score was constructed by assigning weighted values to the variables identified by hazard ratios, combined into an additive mortality risk score equation. One, two and three-year overall mortality rate was 11%, 21% and 32% respectively. Renal failure (HR 1.63; CI 1.15-2.31; p = .006), active neoplasia (HR 1.78; CI 1.27-2.51; p = .008), connective tissue disorder (3.07; CI 1.34-7.08; p = .048), cerebrovascular disease (HR 1.75; CI 1.25-2.46; p = .001) and the use of a single lead device (HR 2.27; CI 1.6-3.24; p < .001) were independently associated with worse survival. The ACP Score showed discrete predictive ability (AUC 0,6792 CI 0,63-0,73). Kaplan-Meier survival curves comparing low vs high ACP Scores demonstrated that low ACP scores were associated with reduced mortality rates (p < .001).

CONCLUSIONS

Significant comorbidities were associated with worse survival after PM implantation in extreme elderly. The ACP Score is a novel tool that may help to identify patients with high mortality risk after device implantation.

Clinical Outcomes of Selective Versus Nonselective His Bundle Pacing

OBJECTIVES

The aim of the study was to evaluate the clinical outcomes of nonselective (NS) His bundle pacing (HBP) compared with selective (S) HBP.

BACKGROUND

HBP is the most physiologic form of ventricular pacing. NS-HBP results in right ventricular septal pre-excitation due to fusion with myocardial capture in addition to His bundle capture resulting in widened QRS duration compared with S-HBP wherein there is exclusive His bundle capture and conduction.

METHODS

The Geisinger and Rush University HBP registries comprise 640 patients who underwent successful HBP. Our study population included 350 consecutive patients treated with HBP for bradyarrhythmic indications who demonstrated ≥20% ventricular pacing burden 3 months post-implantation. Patients were categorized into S-HBP or NS-HBP based on QRS morphology (NS-HBP n = 232; S-HBP n = 118) at the programmed output at the 3-month follow-up. The primary analysis outcome was a combined endpoint of all-cause mortality or heart failure hospitalization.

RESULTS

The NS-HBP group had a higher number of men (64% vs. 50%; p = 0.01), higher incidence of infranodal atrioventricular block (40% vs. 9%; p < 0.01), ischemic cardiomyopathy (24% vs. 14%; p = 0.03), and permanent atrial fibrillation (18% vs. 8%; p = 0.01). The primary endpoint occurred in 81 of 232 patients (35%) in the NS-HBP group compared with 23 of 118 patients (19%) in the S-HBP group (hazard ratio: 1.38; 95% confidence interval: 0.87 to 2.20; p = 0.17). Subgroup analyses of patients at greatest risk (higher pacing burden or lower left ventricular ejection fraction) revealed no incremental risk with NS-HBP.

CONCLUSIONS

NS-HBP was associated with similar outcomes of death or heart failure hospitalization when compared with S-HBP. Multicenter risk-matched clinical studies are needed to confirm these findings.

Is mortality a useful parameter for public reporting in pacemaker implantation? Results of an obligatory external quality control programme

AIMS

To evaluate if public reporting of pacemaker implantation-associated mortality is meaningful in a large contemporary patient cohort.

METHODS AND RESULTS

The database of the obligatory external quality control programme in the Federal State of Hessen, Germany, of patients undergoing permanent pacemaker (PPM) implantation was evaluated retrospectively. We compared the baseline features of patients who died compared with those who did not during hospitalization after PPM. Of 5079 patients who underwent PPM implantation in 2009, 74 (1.5%) died during the hospital stay. Cause of death was available in 70/74 patients (94.6%) who died. Deceased patients were older (79.6 ± 8.7 vs. 76.3 ± 9.9 years, P = 0.006), had worse American Society of Anesthesiologists (ASA) physical status (P < 0.001), lower ejection fraction (P < 0.001), a greater prevalence of high-degree atrioventricular-block (44.3 vs. 35.0%, P = 0.001), and were more likely to receive single-chamber devices (41.4 vs. 25.0%, P < 0.002). Perioperative complications were similar in both cohorts. Death was not attributable directly to PPM procedure in any patients but was related to (i) non-device-related infections (28.6%), (ii) heart failure (25.7%), (iii) extracardiac diseases (21.4%), (iv) multiorgan failure (8.6%), (v) previous resuscitation with hypoxic brain damage (8.6%), and (vi) arrhythmogenic death (7.1%).

CONCLUSION

Mortality associated with PPM implantation in vast majority of cases was not related to the procedure, but to comorbidities and other existing diseases at the time of PPM implantation. Thus, PPM implantation in-hospital mortality should not be chosen for public reporting comparing hospital quality, even after adjusting for baseline risk.

Tolerance of rapid right ventricular pacing during thoracic endovascular aortic repair

BACKGROUND

The objective of this retrospective study was to evaluate the tolerance of rapid right ventricular pacing (RRVP) compared with that of the traditional methods of hypotension used during thoracic endovascular aortic repair (TEVAR).

METHODS

From January 2002 to December 2012, we retrospectively included all the patients treated with TEVAR by comparing the 2 groups: patients operated with RRVP (RRVP+) and those operated without RRVP (RRVP-). The characteristics of the population and the procedures were recorded. The rates of complications were compared up to 1 year.

RESULTS

Sixty-one patients were operated. Treated pathologies were multiple with 19 aneurysms, 14 false aneurysms, 12 isthmic ruptures, 11 dissections, 3 coarctations, and 2 endoleaks. Twenty-four patients were RRVP+ and 37 patients were RRVP-. Mortality rates at 1 month in groups RRVP+ and RRVP- were of 0% and 2.7%, respectively (P = 1), and reintervention rates were 0% and 13.5%, respectively (P = 0.15). Three peroperative rhythm disorders (12.5%) were observed in the RRVP+ group including 2 ventricular fibrillations and 1 atrial fibrillation, both reduced without complications. One pacemaker was implanted for atrioventricular block in the RRVP- group. In the RRVP+ group, 83.3% of the patients presented a rise in troponin Ic (TnI) >0.04 ng/mL in 72 hours compared with 40.5% of the patients in the RRVP- group (P = 0.0013), with a spontaneously favorable evolution. No coronary syndrome was observed at 1 year with a mortality rate of 10.8% in the RRVP- group vs. 0% in the RRVP+ (P = 0.15).

CONCLUSIONS

In spite of a frequent moderate rise of TnI at the time of RRVP, this technique does not present more complications at 1 year than the use of a chemical hypotension. It thus seems an interesting alternative for selected patients, in trained teams.

Outcomes associated with warfarin use in older patients with heart failure and atrial fibrillation and a cardiovascular implantable electronic device: findings from the ADHERE registry linked to Medicare claims

BACKGROUND

Warfarin use and associated outcomes in patients with heart failure and atrial fibrillation and a cardiovascular implantable electronic device have not been described previously.

HYPOTHESIS

We hypothesized that warfarin is underused and is associated with lower risks of mortality, thromboembolic events, and myocardial infarction.

METHODS

Using data from a clinical registry linked with Medicare claims, we examined warfarin use at discharge and 30-day and 1-year Kaplan-Meier estimates of all-cause mortality and cumulative incidence rates of mortality, thromboembolic events, myocardial infarction, and bleeding events in patients 65 years or older, with a history of atrial fibrillation and a cardiovascular implantable electronic device admitted with heart failure between 2001 and 2006, who were naïve to anticoagulation therapy at admission. We compared outcomes between patients who were or were not prescribed warfarin at discharge and tested associations between treatment and outcomes.

RESULTS

Of 2586 eligible patients in 252 hospitals, 2049 were discharged without a prescription for warfarin. At 1 year, the group discharged without warfarin had a higher mortality rate after discharge (37.4% vs 28.8%; P < 0.001) but similar rates of thromboembolism, myocardial infarction, and bleeding events. After adjustment, treatment with warfarin was associated with lower risk of all-cause death 1 year after discharge (hazard ratio: 0.76, 95% confidence interval: 0.63-0.92).

CONCLUSIONS

Among older patients with heart failure and atrial fibrillation and a cardiovascular implantable electronic device, 4 of 5 were discharged without a prescription for warfarin. Warfarin nonuse was associated with a higher risk of death 1 year after discharge. Clin. Cardiol. 2011 DOI: 10.1002/clc.22064 Damon M. Seils, MA, Duke University, assisted with manuscript preparation. Mr. Seils did not receive compensation for his assistance apart from his employment at the institution where the study was conducted. This study was supported by a research agreement between Duke University and Janssen Pharmaceuticals. The authors have no other funding, financial relationships, or conflicts of interest to disclose.

Long-term implications of cumulative right ventricular pacing among patients with an implantable cardioverter-defibrillator

BACKGROUND

Limited data regarding the effect of right ventricular pacing (RVP) on long-term survival following implantable cardioverter-defibrillator (ICD) implantation are available.

OBJECTIVE

The purpose of this study was to evaluate the effect of RVP on the long-term survival benefit of primary ICD therapy.

METHODS

Mortality data were obtained for all patients enrolled in the Multicenter Automatic Defibrillator Trial-II (MADIT-II) during an extended follow-up period of 8 years. The cumulative percent RVP during the trial was categorized as low (≤ 50% [n = 369]) and high (>50% [n = 198]). The benefit of ICD versus non-ICD therapy (n = 490) was evaluated in the two pacing categories during the early (0-3 years) and late (4-8 years) phases of the extended follow-up period.

RESULTS

During the early phase of the extended follow-up period, ICD therapy was associated with similar benefits in the low-RVP and high-RVP subgroups (hazard ratio [HR] = 0.35 and 0.38, respectively, P <.001 for both). In contrast, during the late phase, the long-term survival benefit of the ICD was maintained among patients with low RVP (HR = 0.60, P <.001) and attenuated among those with the high RVP (HR = 0.89, P = .45). An increased risk for late mortality associated with high versus low RVP was evident only among patients without left bundle branch [LBBB] at enrollment (HR = 1.63, P = .002).

CONCLUSION

Among ICD recipients, high RVP is associated with a significant increase in the risk of long-term mortality and with attenuated device efficacy. The deleterious effects of RVP are pronounced mainly in non-LBBB patients, suggesting a possible role for combined cardiac resynchronization-defibrillator therapy in this population.

Acute complications of electrophysiology and pacing procedures: identification and management

Non-pharmacologic interventional techniques for treatment and management of almost all cardiac arrhythmias have greatly expanded over the past decade. These newer interventional electrophysiologic techniques continue to demonstrate increasing success at achieving their targeted goals, and enhancing the patient's quality of life. However, like all interventional procedures, complications may result. In this article we provide the reader with an overview of the more common and significant adverse events that may follow electrophysiologic and pacing procedures, and how best to recognize and manage these complications. After providing the reader with an overview of the complications inherent to all electrophysiologic procedures, we will detail the adverse events intrinsic to specific therapeutic electrophysiologic interventions (DC cardioversion, pharmacologic-based cardioversion, antitachycardia pacing, and ablation of specific arrhythmias). In the last part of the review, we will delineate complications associated with pacing procedures (pacemaker and defibrillator implantation, biventricular pacing and pacing lead extraction).

Delays and adverse clinical outcomes associated with unrecognized pacing indications

BACKGROUND

A recent UK audit showed that a significant proportion of patients who received pacemakers had pacing indications previously overlooked, leading to significant delays to pacemaker implantation.

AIM

To investigate the reasons for, and morbidity associated with, overlooked pacing indications.

DESIGN

Prospective observational study in a UK regional pacing centre and its referring district hospitals.

METHODS

Hospital records from referring and implanting centres were reviewed for 95 consecutive patients undergoing first pacemaker implant to determine symptoms, investigations and hospitalisations occurring after documentation of a pacing indication.

RESULTS

Thirty-three of ninety-five patients (35%) had a pacing indication overlooked, which was Class I in 14 patients and Class IIa in 19. Reasons for not making a pacing referral in these patients included: failure to recognize the indication in 14, making adjustments to potentially culprit medication in 15 and requesting additional 'confirmatory' tests in 4. Twenty-six patients (79%) with missed indications experienced adverse events after documentation of an indication, and before receiving a pacemaker: 23 had ongoing symptoms (including one cardiac arrest), three received temporary pacing wires and 18 were hospitalized with symptoms related to cardiac rhythm. Twenty-seven patients (82%) had a total of 38 additional specialist investigations after documentation of a pacing indication.

CONCLUSION

Documentation of an indication for pacing failed to trigger referral for permanent pacing in 35% of patients. This failure led to significant delays, morbidity and use of health service resource, which may have been avoided if timely recognition of the pacing indication had prompted referral. Failure to recognize pacing indications and reassessing symptoms and repeating investigation after changes to medication, often required for the management of associated tachyarrhythmias or other medical conditions, contribute to these delays, perhaps unnecessarily.

[Upgrading to biventricular pacing: indications and procedural challenges]

Upgrading RV pacing systems to biventricular resynchronization modalities is a promising option for paced patients with worsening heart failure. The potentially favorable effect of upgrading has been demonstrated in several, non-randomized trials. Selection of eligible patients and technical aspects of the procedure are described. The most common procedure-related complications are reported.

[Role of right heart failure in cardiac resynchronization]

During recent years cardiac resynchronization has become an important tool in the treatment of patients with signs and symptoms of heart failure and desynchronized contraction of the left ventricle. Among patients with heart failure, right ventricular involvement can occur because the underlying disease affects both ventricles or because the reduction of left ventricular function impairs the right ventricular function by altered coupling and increased right ventricular afterload. Irrespective of the underlying cause the reduction of right ventricular function confers an adverse prognosis that is further aggravated by the presence of pulmonary hypertension. The present article describes the relevance of reduced right ventricular function for the clinical syndrome of heart failure, the role of right ventricular resynchronization in patients with predominant right heart failure and the possible effects of left ventricular resynchronization on a preexisting impairment of right ventricular function.

[Is resynchronization therapy necessary when optimizing right ventricular stimulation?]

Cardiac resynchronization therapy (CRT) using biventricular stimulation is hampered by coronary venous imponderabilities, complex implantation procedures, technical malfunctions and complications as well as disappointing responder rates. Despite its pathophysiological soundness and some initial success, the use of AV sequential pacing for the treatment of heart failure has been abandoned because right ventricular (RV) apical stimulation may be detrimental for cardiac mechanics, may worsen heart failure and may increase mortality. Attempts at avoiding desynchronizing effects and improving hemodynamics by pacing from alternative RV sites have been numerous but not convincing. Whether patients with left ventricular dysfunction or overt heart failure may benefit from pacing the RV outflow tract or septum, from dual site RV or His bundle stimulation instead of left ventricular based resynchronization is the topic of this review.

Mitral valve regurgitation and left ventricular systolic dysfunction: corrective surgery or cardiac resynchronization therapy?

Mitral regurgitation (MR) can be found in a sizeable percentage of patients with chronic congestive heart failure (CHF) and systolic left ventricular (LV) dysfunction despite a structurally normal valve. This functional or secondary regurgitation results from a dysbalance between closing and opening forces on the mitral leaflets due to reduced LV contractility, geometric distortion of the subvalvular apparatus, and global dilatation of the left ventricle and the mitral annulus. MR in LV dysfunction has a negative impact on both symptoms and prognosis. Surgical correction of secondary MR remained controversial although it was found to be technically feasible and to provide symptomatic benefit in some (mostly) mono-center series. Cardiac resynchronization therapy (CRT) was also found to improve secondary mitral regurgitation. However, the prediction in which patient significant secondary MR will improve with CRT is largely unresolved. The following paper reviews the available data concerning the two major interventional options for significant secondary MR in patients with CHF and systolic LV dysfunction, i.e. mitral valve surgery vs. CRT, and describes our institutional approach to this problem.

Cardiac pacing in hypertrophic cardiomyopathy: a cohort with 24 years of follow-up

BACKGROUND

The benefits of heart stimulation in hypertrophic cardiomyopathy (HCM) patients have been questioned. Research work available in Brazil on those benefits is scarce.

OBJECTIVE

To describe the indication, clinical response, complications and survival time related to pacemaker implant in HCM patients.

METHODS

Thirty-nine hypertrophic cardiomyopathy patients were studied (41% males) and submitted to pacemaker implant from May, 1980 through November, 2003.

RESULTS

Twenty-seven patients presented obstructive hypertrophic cardiomyopathy, and 12, non-obstructive. Mean age was 46.4 years of age (range 14-77), with follow-up of 6.4+/-4.1 years. Major indications for implant were: spontaneous or induced atrioventricular block (54%), refractoriness to therapeutic conduct associated to high gradient (33%), support for drug therapy to treat bradychardia (8%), and atrial fibrillation prevention (5%). Functional class was shown to improve from 2.41+/-0.87 to 1.97+/-0.92 (p=0.008), and symptoms referred were reduced. No change was made in drug therapy administration. No procedure-related deaths were reported. Although shown to be safe, the procedure was not free from complications (6 patients--15.4%). Three deaths occurred in the follow-up period--the three of them were atrial fibrillation female patients, with evidence of functional deterioration. A close association was observed between clinical condition worsening and the onset of atrial fibrillation or flutter.

CONCLUSION

Cardiac pacing in HCM patients was successful, with evidence of symptoms relief in obstructive HCM patients. No functional improvement was observed in non-obstructive patients.

Cardiac resynchronization therapy and its potential proarrhythmic effect

Cardiac resynchronization therapy (CRT) has become an established adjunctive treatment to optimal pharmacologic therapy in patients with advanced chronic heart failure (CHF), diminished left ventricular (LV) function and intraventricular conduction delay. Although CRT has been shown to improve ventricular hemodynamics, quality of life and exercise capacity, there is some evidence that it may rarely potentiate ventricular arrhythmias. As CRT is considered for an expanded population of CHF patients, and left-sided pacing is considered as an option for pacemaker-indicated patients (potentially without defibrillator backup), the effect of these pacing modalities on the incidence of ventricular tachyarrhythmia must be systematically studied and mechanistically understood. Strategies to prospectively predict the proarrhythmic potential of LV epicardial pacing need to be developed, and therapy accordingly individualized. This review attempts to summarize the current information on proarrhythmia in resynchronization therapy.

Determinants of pacemaker dependency after coronary and/or mitral or aortic valve surgery with long-term follow-up

The aim of the present study was to investigate potential preoperative, operative, and postoperative predictors of pacemaker (PM) dependency after coronary, mitral valve, and aortic valve surgery. One hundred two patients (mean age 68 +/- 11 years; 62% men) who had received a permanent PM after cardiac surgery were included. The presence of any pacing activity in VVI mode with a lower rate of 30 beats/min was defined as PM dependency. Median time to PM implantation was 10 days after the index surgery. Pacemaker indications were atrioventricular block (AVB), sinus node dysfunction, and slow atrial fibrillation in 70%, 20%, and 11% of patients, respectively. At baseline, PM dependency rates were 0%, 9%, and 15% for patients with sinus node dysfunction, slow atrial fibrillation, and AVB, respectively (p = 0.158). Corresponding values at last follow-up were 15%, 9%, and 41% (p = 0.02). During long-term follow-up, new PM dependency developed in 21 patients (23%). Most patients had AVB as the PM indication (18 of 21 patients; 86%). Cumulative probabilities of freedom from PM dependency in patients with AVB were 63% and 30% at 5 and 10 years, respectively. Of several demographic, preoperative clinical, electrocardiographic, operative, and postoperative characteristics of patients, preoperative history of syncope (odds ratio [OR] 6.58, 95% confidence interval [CI] 1.11 to 38.87), body mass index >or=28.5 kg/m2 (OR 2.88, 95% CI 1.08 to 7.67), bypass time >or=105 minutes (OR 4.81, 95% CI 1.54 to 15.02), and AVB as PM indication (OR 5.14, 95% CI 1.51 to 17.44) were independent predictors of long-term PM dependency in multivariate logistic regression analysis. In conclusion, the long-term PM dependency rate was relatively high in patients with postoperative AVB requiring permanent PM implantation. A preoperative history of syncope, body mass index >or=28.5 kg/m2, bypass time of 105 minutes, and AVB as PM indication were independent predictors of long-term PM dependency after cardiac surgery.

Effect of Posterolateral Left Ventricular Scar on Mortality and Morbidity following Cardiac Resynchronization Therapy

OBJECTIVES

To determine the effect of a posterolateral (PL) left ventricular scar on mortality and morbidity following cardiac resynchronization therapy (CRT).

METHODS

Sixty-two patients with heart failure (age 67.3 +/- 9.6 yrs [mean +/- SD], 45 males, New York Heart Association class [NYHA] class III or IV, left ventricular ejection fraction [LVEF]= 35%, left bundle branch block, QRS > or = 120 ms) underwent late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) for scar imaging. Patients were followed up for 741 (75-1602) days (mean [range]).

RESULTS

The presence of a PL scar emerged as an independent predictor of the composite endpoint of cardiovascular death or hospitalization for worsening heart failure (HR: 3.06 [1.63, 7.7, P < 0.0001]) as well as the endpoint of cardiovascular death (HR: 2.63 [1.39, 6.65], P = 0.0016). A transmural PL scar was the strongest predictor of these endpoints (both P < 0.0001). The symptomatic responder rate (improvement by > or =1 NYHA classes or > or =25% in 6-min walking distance) was 83% in the group with non-PL scars, but only 47% in the group with transmural PL scars (P < 0.0001). Pacing over the scar was associated with a higher mortality and morbidity than pacing outside the scar (all P < 0.05).

CONCLUSIONS

A PL scar is associated with a worse clinical outcome following CRT, particularly if it is transmural. Pacing scarred left ventricular myocardium carries a greater risk of mortality and morbidity than pacing nonscarred myocardium.

Response to Cardiac Resynchronization Therapy Predicts Survival in Heart Failure: A Single-Center Experience

OBJECTIVE

To determine whether survival after cardiac resynchronization therapy (CRT) is related to improvement in clinical or echocardiographic parameters.

BACKGROUND

In clinical trials, CRT improved symptoms, left ventricular (LV) structure, function, and survival. In clinical practice, response to CRT is highly variable and whether survival benefit is confined to those patients who experience improvement in clinical status or cardiac structure and function is unclear.

METHODS

This is a single-center study of patients receiving clinically indicated CRT between January 2002 and December 2004.

RESULTS

Of 309 patients (age 68 +/- 11 years, 83% male) receiving CRT at our institution during the study period, 174 returned for follow-up and 127 had repeat echocardiography. Baseline clinical characteristics and survival were similar among those who did or did not return for follow-up. In paired analyses, New York Heart Association (NYHA) class (-0.56 +/- 0.07, p < 0.0001), ejection fraction (EF, 6.3 +/- 0.7%, P < 0.0001), LV dimension (-2.7 +/- 0.6 mm, P < 0.0001), pulmonary artery systolic pressure (PASP, -4.6 +/- 1.3 mm Hg, P = 0.0007), and MR severity grade (-0.20 +/- 0.05, P = 0.0002) improved after CRT. Survival after CRT was associated with decrease in NYHA class (risk ratio [RR]= 0.43, P = 0.0004), increase in EF (RR = 0.94, P = 0.02), and decrease in PASP (RR = 0.96, P = 0.03). Change in EF and NYHA class were correlated (r = -0.46, P < 0.0001) and, adjusting for this covariance, change in NYHA (P = 0.04) but not EF (P = 0.12) was associated with improved survival.

CONCLUSION

Patients who experience improved symptoms, ventricular function, and/or hemodynamics have better survival after CRT. These data enhance understanding of the relationship between CRT clinical response and survival benefit in clinical practice.

Comparison of the effects of cardiac resynchronization therapy in patients with class II versus class III and IV heart failure (from the InSync/InSync ICD Italian Registry)

Cardiac resynchronization therapy (CRT) is recommended for patients with New York Heart Association (NYHA) class III or IV heart failure and wide QRS complexes. The aim of this study was to compare the effects of CRT in patients in NYHA class II with those in NYHA class III or IV. Nine hundred fifty-two patients (188 in NYHA class II) consecutively implanted with biventricular devices and enrolled in a national observational registry were studied. Clinical outcomes were estimated after 12 months of CRT, and long-term survival was assessed. At a median follow-up of 16 months, significantly fewer major cardiovascular events were reported in patients in NYHA class II compared with NYHA class III or IV (rate 13 vs 23 per 100 patient-years of follow-up, p<0.001). The percentage of patients who improved in NYHA class status after 12 months of CRT was lower in those in class II than in those in class III or IV (34% vs 69%, p<0.001), whereas the absolute increase in the ejection fraction was similar (8+/-9% vs 9+/-11%, p=NS), as well as the reductions in end-diastolic diameter (-3+/-8 vs -3+/-8 mm, p=NS) and end-systolic diameter (-4+/-10 vs -6+/-10 mm, p=NS). The NYHA class II group experienced lower all-cause mortality (log-rank test p=0.018). In the 2 groups, patients with major cardiovascular events during follow-up exhibited less or no reverse remodeling compared with those with better long-term clinical outcomes. In conclusion, the results of this study indicate that CRT induced similar improvements in ventricular function in the 2 groups, whereas the improvement in functional status was significantly lower for patients in NYHA class II than for those in class III or IV. A positive effect of CRT on cardiac dimensions was associated with a long-term beneficial effect on disease progression in patients in NYHA class II.

Efficacy of cardiac resynchronization therapy in very old patients: the Insync/Insync ICD Italian Registry

AIMS

To assess the effects of cardiac resynchronization therapy (CRT) in > or =80-year-old patients vs. patients <80 years, in terms of clinical, functional, and echocardiographic parameters after 12 month of CRT, survival, and incidence of arrhythmic events.

METHODS AND RESULTS

The study population consisted of 1181 CRT patients (85 were > or =80 years old). They were enrolled in a national observational registry and underwent baseline evaluation and periodical follow-up visits. In the overall population, New York Heart Association class and ejection fraction (EF) improved and ventricular diameters decreased. Similar changes were observed in the two groups. In the study population, 157 patients died, 144 (13%) in the <80 years group and 13 (15%) in the > or =80 years group. There was a higher all-cause mortality (log-rank test, P = 0.015) among > or =80 years patients, with a trend towards higher sudden cardiac death (SCD) (P = 0.057), but similar non-SCD (P = 0.293). Using the combined endpoint of SCD or appropriate shock from a defibrillator for ventricular fibrillation, no significant differences resulted between groups (P = 0.455). In both groups, lower EF was associated with higher mortality.

CONCLUSION

Cardiac resynchronization therapy demonstrated similar efficacy in patients aged > or =80 years and in those under 80, in terms of clinical and functional parameters and reverse remodelling. Similarly, CRT resulted in comparable effects on death for heart failure and on SCD.

Single Chamber Atrial Pacing: A Realistic Option in Sinus Node Disease: A Long-Term Follow-up Study of 213 Patients

BACKGROUND

Despite several decades of experience with atrial pacing, many centers do not apply this mode to any greater extent, mainly because of concerns for the development of future atrioventricular (AV) block or atrial fibrillation. Recent studies have emphasized possible negative effects of right ventricular stimulation, even when AV-synchrony is preserved, and have thus given rise to renewed interest in single chamber atrial pacing for sinus node disease.

METHODS

This study presents the results of up to 19 years' follow-up of 213 patients with sinus node disease treated with atrial pacing with respect to survival and causes of death, development of atrial fibrillation and AV block, and total mode survival. Patients were divided into two groups: with or without associated atrial tachyarrhythmias at the time of implant. Results are given for all patients and for the two groups separately.

RESULTS

The mean follow-up time was 10.1 years. The survival of the entire group was lower after 10 years than that of an age and gender-matched general Swedish population. This was caused by patients with the brady-tachy syndrome (BT) having a significantly higher mortality rate than controls, whereas those with bradycardia only (B) had survival comparable to the general population. Permanent atrial fibrillation (AF) developed in 20% of patients and was significantly more common in patients with BT. The majority of patients with AF (78%) no longer needed any pacing, i.e., did not require ventricular stimulation due to slow ventricular rate. The annual incidence of high grade AV block was 1.8%. If patients with preexisting bundle branch block were excluded, the incidence was 1.6%. No fatal episode of AV block was seen. The overall mode survival at the end of follow-up was 75%, with 155 patients still with atrial pacemakers.

CONCLUSION

Atrial pacing is a safe and reliable mode of pacing in patients with sinus node disease, even in the very long-term.

Implantation of cardiac resynchronization therapy systems in the CARE-HF trial: procedural success rate and safety

AIMS

To assess procedural characteristics and adjudicated procedure-related (<or=30 days) major adverse events among patients who underwent cardiac resynchronization therapy (CRT) implantation in the CARE-HF study. The CARE-HF study shows that CRT improves symptoms and reduces morbidity and mortality in New York Heart Association (NYHA) class III/IV chronic heart failure (CHF) patients. However, safe and proper implantation of pacing systems remains key to effective CRT delivery.

METHODS AND RESULTS

Generalized linear modeling was used to examine the relationships between first implant success/failure and: NYHA class; beta-adrenergic blocker use; underlying ischemic vs. non-ischemic heart disease; history of coronary artery bypass graft or valve surgery; left ventricular (LV) end-diastolic volume<or=vs. >300 cm(3); and, influence of the participating study-centres. Implantation was attempted in 404/409 patients assigned to CRT, and in 65/404 patients assigned to medical therapy. Among these 469 patients, 450 (95.9%) received a successfully implanted and activated device. Complications occurred within 24 h in 47 patients (10.0%), mainly lead dislodgments (n = 10, 2.1%) and coronary sinus dissection/perforation (n = 10, 2.1%), and between 24 h and 30 days in 26 patients (5.5%), mainly lead dislodgment (n = 13, 2.8%). Mean LV lead stimulation threshold was significantly higher than at the right atrium or right ventricle, though remained stable, delivering effective, and reliable CRT. Implanting experience was the only predictor of procedural outcome.

CONCLUSION

Transvenous CRT system implantation, using a CS lead designed for long-term LV pacing, was safe and reliable. As implanting centres become more experienced, this success rate is expected to increase further.

Long-term survival in patients treated with cardiac resynchronization therapy: a 3-year follow-up study from the InSync/InSync ICD Italian Registry

BACKGROUND

Studies reporting the long-term survival of patients treated with cardiac resynchronization therapy (CRT) outside the realm of randomized controlled trials are still lacking. The aim of this study was to quantify the survival of patients treated with CRT in clinical practice and to investigate the long-term effects of CRT on clinical status and echocardiographic parameters.

METHODS

The study population consisted of 317 consecutive patients with implanted CRT devices from eight Italian University/Teaching Hospitals. The patients were enrolled in a national observational registry and had a minimum follow-up of 2 years. A visit was performed in surviving patients and mortality data were obtained by hospital file review or direct telephone contact.

RESULTS

During the study period, 83 (26%) patients died. The rate of all-cause mortality was significantly higher in ischemic than nonischemic patients (14% vs 8%, P = 0.002). Multivariate analysis showed that ischemic etiology (HR 1.72, CI 1.06-2.79; P = 0.028) and New York Heart Association (NYHA) class IV (HR 2.87, CI 1.24-6.64; P = 0.014) were the strongest predictors of all-cause mortality. The effects of CRT persisted at long-term follow-up (for at least 2 years) in terms of NYHA class improvement, increase of left ventricular ejection fraction, decrease of QRS duration (all P = 0.0001), and reduction of left ventricular end-diastolic and end-systolic diameters (P = 0.024 and P = 0.011, respectively).

CONCLUSIONS

During long-term (3 years) follow-up after CRT, total mortality rate was 10%/year. The outcome of ischemic patients was worse mainly due to a higher rate of death from progressive heart failure. Ischemic etiology along with NYHA class IV was identified as predictors of death. Benefits of CRT in terms of clinical function and echocardiographic parameters persisted at the time of long-term follow-up.

Long-term follow-up after pacemaker implantation in neonates and infants

BACKGROUND

Pacemaker (PM) system implantation in neonates and infants is often complicated by hemodynamic instability, small vessel size, and abnormal cardiovascular anatomy. Thus, an open surgical approach for epicardial lead insertion is often required. We assessed the long-term outcomes after epicardial PM implantation in this age group.

METHODS

Between 1992 and 2004, 22 consecutive patients underwent PM implantation within the first year of life. Bipolar steroid-eluting epicardial leads (Medtronic CapSure Epi 10366 and 4968) were inserted through median sternotomy, the sybxyphoid approach, or thoracotomy, and connected to various pulse generators.

RESULTS

Pacemakers were implanted at a median age of 35 days (range, 1 to 300). Intracardiac anatomy was abnormal in 17 patients. Indications for PM therapy were heart block in 18 patients and sinus node dysfunction in 4 patients. During a median follow-up of 4.6 years (range, 4 days to 12.8 years), 7 devices were replaced owing to end of battery life (n = 6) or elective device repositioning (n = 1), at a median of 4.1 years (range, 1 to 7.8). One dislodged ventricular lead and 2 atrial lead sensing failures were observed. Sensing, pacing thresholds, and lead impedances showed good implant and stable follow-up values.

CONCLUSIONS

Pacemaker-associated morbidity is low. Pacemaker system complications with epicardial leads are rare. Battery life is relatively shorter compared with children and adults because of the fast heart rate and complete PM dependency in most of these children. Even for neonates and infants, modern pacemaker therapy is feasible, safe, and effective.

Effects of Cardiac Resynchronization Therapy With or Without a Defibrillator on Survival and Hospitalizations in Patients With New York Heart Association Class IV Heart Failure

Background— Cardiac resynchronization therapy (CRT) alone or combined with an implantable defibrillator (CRT-D) has been shown to improve exercise capacity and quality of life and to reduce heart failure (HF) hospitalizations and mortality in patients with New York Heart Association (NYHA) class III and IV HF. There is concern that the device procedure may destabilize these very ill class IV patients. We sought to examine the outcomes of NYHA class IV patients enrolled in the Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION) trial to assess the potential benefits of CRT and CRT-D.

Methods and Results— The COMPANION trial randomized 1520 patients with NYHA class III and IV HF to optimal medical therapy, CRT, or CRT-D. In the class IV patients (n=217), the primary end point of time to death or hospitalization for any cause was significantly improved by both CRT (hazard ratio [HR], 0.64; 95% CI, 0.43 to 0.94; P =0.02) and CRT-D (HR, 0.62; 95% CI, 0.42 to 0.90; P =0.01). Time to all-cause death and HF hospitalization was also significantly improved in both CRT (HR, 0.57; 95% CI, 0.37 to 0.87; P =0.01) and CRT-D (HR, 0.49; 95% CI, 0.32 to 0.75; P =0.001) Time to all-cause death trended to an improvement in both CRT (HR, 0.67; 95% CI, 0.41 to 1.10; P =0.11) and CRT-D (HR, 0.63; 95% CI, 0.39 to 1.03; P =0.06). Time to sudden death appeared to be significantly reduced in the CRT-D group (HR, 0.27; 95% CI, 0.08 to 0.90; P =0.03). There was a nonsignificant reduction in time to HF deaths for both CRT (HR, 0.68; 95% CI, 0.34 to 1.37; P =0.28) and CRT-D (HR, 0.79; 95% CI, 0.41 to 1.52; P =0.48).

Conclusions— CRT and CRT-D significantly improve time to all-cause mortality and hospitalizations in NYHA class IV patients, with a trend for improved mortality. These devices should be considered in ambulatory NYHA class IV HF patients similar to those enrolled in COMPANION.

Cardiac resynchronization therapy in chronic heart failure

Cardiac resynchronisation therapy (CRT) has emerged as a treatment option for patients with severe, drug-refractory heart failure and signs of intraventricular dyssynchrony. In clinical trials CRT reduced the overall mortality, improved symptoms, exercise tolerance, and left ventricular function, as compared with optimised medical therapy alone. One of the challenging fields in patient selection for CRT is to identify the 20-30% of heart failure patients with bundle branch block that will not respond to this novel therapy. Other fields of uncertainty, such as CRT in patients with atrial fibrillation or chronic right ventricular stimulation as well as the role of a back-up defibrillator will be discussed.

Does intensity of rate-control influence outcome in atrial fibrillation? An analysis of pooled data from the RACE and AFFIRM studies

AIMS

The AFFIRM and RACE studies showed that rate control is an acceptable treatment strategy for atrial fibrillation (AF). We examined whether strict rate control offers benefit over more lenient rate control.

METHODS AND RESULTS

We compared the outcome of patients enrolled in the rate-control arms of AFFIRM and RACE, using data from patients who met a composite of overlapping inclusion and exclusion criteria. We evaluated 1091 patients, 874 from AFFIRM and 217 from RACE. In AFFIRM, the rate-control strategy aimed for a resting heart rate < or =80 bpm and heart rate during daily activity of < or =110 bpm. In RACE, a more lenient approach was taken: resting heart rate <100 bpm. Primary endpoint was a composite of mortality, cardiovascular hospitalization, and myocardial infarction. Mean heart rate across all follow-up visits for patients in AF was lower in AFFIRM (76.1 vs. 83.4 bpm). Event-free survival for the occurrence of the primary endpoint did not differ (64% in AFFIRM vs. 66% in RACE). Patients with mean heart rates during AF within the AFFIRM (< or =80) or RACE (<100) criteria had a better outcome than patients with heart rates > or =100 (hazard ratios 0.69 and 0.58, respectively, for < or =80 and <100 compared with > or =100 bpm).

CONCLUSION

Stringency of the approach to rate control, based on the comparison of the AFFIRM and RACE studies, was not associated with an important difference in clinical events.

Cardiac resynchronisation therapy for heart failure

Cardiac resynchronisation therapy (CRT) reduces symptoms and improves left ventricular function in chronic heart failure (CHF) patients with left ventricular systolic dysfunction and prolonged QRS duration. Recent studies have demonstrated a reduction in mortality associated with CRT. When combined with an implantable cardioverter defibrillator (ICD) reduction in mortality is likely to reduce further. Cardiac resynchronisation therapy is well tolerated and free from compliance issues and therefore should be considered for all suitable patients. Identifying patients who will derive maximum benefit requires further study and has health economic implications. We review here the CRT trial evidence as well as the implantation technique and complications. We also describe a case report where an intra-aortic balloon pump was used successfully as a bridge to CRT to treat a patient with end-stage heart failure.

Longer-term effects of cardiac resynchronization therapy on mortality in heart failure [the CArdiac REsynchronization-Heart Failure (CARE-HF) trial extension phase]

AIMS

The CArdiac REsynchronization-Heart Failure study randomized patients with left ventricular ejection fraction < or =35%, markers of cardiac dyssynchrony, and persistent moderate or severe symptoms of heart failure despite pharmacological therapy, to implantation of a cardiac resynchronization therapy (CRT) device or not. The main study observed substantial benefits on morbidity and mortality during a mean follow-up of 29.4 months [median 29.6, interquartile range (IQR) 23.6-34.6]. Prior to study closure, an extension phase lasting a further 8 months (allowing time for data analysis and presentation) was declared during which cross-over was discouraged.

METHODS AND RESULTS

This was an extension of the already reported open-label randomized trial described above. The primary outcome of the extension phase was all-cause mortality from the time of randomization to completion of the extension phase. The secondary outcome was mode of death. The mean follow-up was 37.4 months (median 37.6, IQR 31.5-42.5, range 26.1-52.6 months). There were 154 deaths (38.1%) in 404 patients assigned to medical therapy and 101 deaths (24.7%) in 409 patients assigned to CRT (hazard ratio 0.60, 95% CI 0.47-0.77, P<0.0001) without evidence of heterogeneity in pre-specified subgroups. A reduction in the risk of death due to heart failure (64 vs. 38 deaths; hazard ratio 0.55, 95% CI 0.37-0.82, P=0.003) and sudden death was observed (55 vs. 32; hazard ratio 0.54, 95% CI 0.35-0.84, P=0.005).

CONCLUSION

The benefits of CRT observed in the main trial persist or increase with longer follow-up. Reduction in mortality was due to fewer deaths both from worsening heart failure and from sudden death.

The long-term cost-effectiveness of cardiac resynchronization therapy with or without an implantable cardioverter-defibrillator

AIMS

Cardiac resynchronization therapy (CRT-P) is an effective treatment for patients with heart failure and cardiac dyssynchrony with moderate or severe symptoms despite pharmacological therapy. The addition of an implantable cardioverter-defibrillator (ICD) function may further reduce the risk of sudden death. We assessed the cost-effectiveness of CRT-P compared with medical therapy (MT) alone, and the cost-effectiveness of CRT-ICD + MT compared with CRT-P + MT, on incremental cost per quality adjusted life year (QALY) and life year using data from two landmark clinical trials.

METHODS AND RESULTS

A Markov model with Monte Carlo simulation to assess costs, life years, and QALYs associated with CRT (+/- ICD) and MT in patients with heart failure and cardiac dyssynchrony, on the basis of a UK healthcare perspective was constructed. NYHA class distribution and transitions, associated health utilities, rates and cause of hospitalization and death were estimated from individual patient data from the CArdiac REsychronization in Heart Failure (CARE-HF trial). The estimated additional benefit on survival of an ICD was based on results from COMPANION. The base case analysis used 10 000 individual life-time simulations assuming a battery life of 6 years for CRT-P and 7 years for CRT-ICD. From a life-time perspective in a 65-year-old patient, the incremental cost-effectiveness of CRT-P compared with MT is 7538 euros (95% CI 5325-11,784 euros) per QALY gained and 7011euros (95% CI 5346-10,003 euros) per life year gained. The incremental cost-effectiveness of CRT-ICD compared with CRT-P is 47,909 euros (95% CI 35,703-79,438 euros) per QALY gained, and 35,864 euros (95% CI 26,709-56,353 euros) per life year gained.

CONCLUSION

Long-term treatment with CRT-P appears cost-effective compared with MT alone. From a life-time perspective, assuming a reasonable life expectancy when receiving effective treatment for heart failure, CRT-ICD may also be considered cost-effective when compared with CRT-P + MT.

Modelling the economic and health consequences of cardiac resynchronization therapy in the UK

OBJECTIVE

Clinical evidence supports the use of cardiac resynchronization therapy (CRT) in advanced heart failure, but its cost-effectiveness is still unclear. This analysis assessed the economic and health consequences in the UK of implanting a CRT in patients with NYHA class III-IV heart failure.

METHODS

A discrete event simulation of heart failure was used to compare the course over 5 years of 1000 identical pairs of patients -- one receiving both CRT and optimum pharmacologic treatment (OPT), the other OPT alone. All inputs were obtained from the data collected in the CArdiac REsynchronization in Heart Failure (CARE-HF) trial and a hospital in the UK. Direct medical costs (in 2004 pound) from the perspective of the National Health Service were considered. Both costs and benefits were discounted at 3.5%. Sensitivity analyses addressed all model inputs and multivariate analyses were performed by varying key parameters simultaneously.

RESULTS

The model predicted 471 deaths and 2263 hospitalizations over 5 years with OPT alone and 348 deaths and 1764 hospitalizations with CRT, equivalent to a 26% reduction in mortality and 22% in hospitalizations, at a discounted cost of pound 11,423 per patient with CRT vs. pound 4,900 with OPT alone. CRT was predicted to increase quality-adjusted survival by 0.43 QALYs per patient, resulting in an incremental cost-effectiveness ratio of pound 15,247 per QALY gained (range: pound 12,531- pound 23,184). Sensitivity analyses revealed that this outcome was most sensitive to time horizon and cost of implantation.

CONCLUSION

Based on these 5-year analyses, CRT is expected to yield substantial health benefits at a reasonable cost.

Randomized comparison of simultaneous biventricular stimulation versus optimized interventricular delay in cardiac resynchronization therapy. The Resynchronization for the HemodYnamic Treatment for Heart Failure Management II implantable cardioverter defibrillator (RHYTHM II ICD) study

BACKGROUND

The clinical value of interventricular (V-V) delay optimization in patients with chronic congestive heart failure (CHF) undergoing implantation of a device for cardiac resynchronization therapy (CRT) has not been clearly demonstrated.

METHODS

RHYTHM II was a single-blind randomized trial including 121 recipients of a device for CRT with cardioverter/defibrillator capabilities (CRT-D) randomly assigned in a 1:3 ratio to simultaneous (n = 30) versus optimized (OPT) (n = 91) biventricular pacing. V-V delay was optimized by echocardiography. The study end points were (1) freedom from CRT-D system-related complications and (2) changes between preimplant and 6 months of follow-up in (a) New York Heart Association CHF functional class, (b) distance covered during a 6-minute hall walk, and (c) quality of life (QOL).

RESULTS

In the OPT group, the V-V delay ranged from 0 to 80 milliseconds, with 28.4% of patients stimulated at an OPT V-V delay of 0 milliseconds. The overall 6-month survival free of adverse events requiring invasive interventions was 81.8%. In the whole cohort, 6 months of CRT-D was associated with a significant decrease in New York Heart Association class, increase in the distance covered during the 6-minute hall walk, and improvement in QOL (each P < .0001). The effects of CRT-D on these end points were similar in both study groups.

CONCLUSIONS

Cardioverter-defibrillator capabilities was associated with a significant alleviation of CHF symptoms, increase in functional capacity, and improvement in QOL. The optimization of the V-V delay conferred no additional benefit compared with simultaneous biventricular stimulation.

Resynchronization Therapy in Pediatric and Congenital Heart Disease Patients

OBJECTIVES

Our objective was to evaluate the short-term safety and efficacy of cardiac resynchronization therapy (CRT) in children.

BACKGROUND

Cardiac resynchronization therapy has been beneficial for adult patients with poor left ventricular function and intraventricular conduction delay. The efficacy of this therapy in the young and in those with congenital heart disease (CHD) has not yet been established.

METHODS

This is a multi-center, retrospective evaluation of CRT in 103 patients from 22 institutions.

RESULTS

Median age at time of implantation was 12.8 years (3 months to 55.4 years). Median duration of follow-up was four months (22 days to 1 year). The diagnosis was CHD in 73 patients (71%), cardiomyopathy in 16 (16%), and congenital complete atrioventricular block in 14 (13%). The QRS duration before pacing was 166.1 +/- 33.3 ms, which decreased after CRT by 37.7 +/- 30.7 ms (p < 0.01). Pre-CRT systemic ventricular ejection fraction (EF) was 26.2 +/- 11.6%. The EF increased by 12.8 +/- 12.7 EF units with a mean EF after CRT of 39.9 +/- 14.8% (p < 0.05). Of 18 patients who underwent CRT while listed for heart transplantation, 3 improved sufficiently to allow removal from the transplant waiting list, 5 underwent transplant, 2 died, and 8 others are currently awaiting transplant.

CONCLUSIONS

Cardiac resynchronization therapy appears to offer benefit in pediatric and CHD patients who differ substantially from the adult populations in whom this therapy has been most thoroughly evaluated to date. Further studies looking at the long-term benefit of this therapy in this population are needed.

Cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) addresses abnormal left ventricular (LV) activation that produces detrimental effects on cardiac systolic and diastolic function. CRT improves symptoms and ventricular performance, promotes reverse remodeling, and decreases mortality and hospitalization in patients with congestive heart failure (CHF). Atrial-synchronized biventricular stimulation reverses many of the temporal delays in mechanical activation associated with LV dysfunction and conduction system disease. The therapy evolved from anecdotal application through surgical implantation of LV pacing leads to transvenous delivery of LV pacing leads for use with dedicated CRT devices. The controlled clinical trials included specific patient groups, and provided data leading to widely adopted indications for the therapy. Current indications exclude the use of CRT in patients with permanent atrial fibrillation, although small series suggest a benefit of the therapy in these patients. The role of cardiac imaging with echocardiography to detect cardiac dyssynchrony promises to improve patient selection by not only excluding likely nonresponders, but also extending the therapy to those with dyssynchrony in the absence of QRS prolongation. Expanded indications under evaluation include the role of CRT in patients with mildly symptomatic CHF, mild to moderate LV dysfunction, dyssynchrony in the absence of QRS prolongation, and dyssynchrony induced by right ventricular pacing.

Single-chamber versus dual-chamber pacing for high-grade atrioventricular block

BACKGROUND

In the treatment of atrioventricular block, dual-chamber cardiac pacing is thought to confer a clinical benefit as compared with single-chamber ventricular pacing, but the supporting evidence is mainly from retrospective studies. Uncertainty persists regarding the true benefits of dual-chamber pacing, particularly in the elderly, in whom it is used less often than in younger patients.

METHODS

In a multicenter, randomized, parallel-group trial, 2021 patients 70 years of age or older who were undergoing their first pacemaker implant for high-grade atrioventricular block were randomly assigned to receive a single-chamber ventricular pacemaker (1009 patients) or a dual-chamber pacemaker (1012 patients). In the single-chamber group, patients were randomly assigned to receive either fixed-rate pacing (504 patients) or rate-adaptive pacing (505 patients). The primary outcome was death from all causes. Secondary outcomes included atrial fibrillation, heart failure, and a composite of stroke, transient ischemic attack, or other thromboembolism.

RESULTS

The median follow-up period was 4.6 years for mortality and 3 years for other cardiovascular events. The mean annual mortality rate was 7.2 percent in the single-chamber group and 7.4 percent in the dual-chamber group (hazard ratio, 0.96; 95 percent confidence interval, 0.83 to 1.11). We found no significant differences between the group with single-chamber pacing and that with dual-chamber pacing in the rates of atrial fibrillation, heart failure, or a composite of stroke, transient ischemic attack, or other thromboembolism.

CONCLUSIONS

In elderly patients with high-grade atrioventricular block, the pacing mode does not influence the rate of death from all causes during the first five years or the incidence of cardiovascular events during the first three years after implantation of a pacemaker.

The prognostic value of pharmacologic stress myocardial perfusion imaging in patients with permanent pacemakers

BACKGROUND

The aim of this study is to assess the prognostic value of pharmacologic stress (adenosine or dipyridamole) myocardial perfusion imaging in patients with permanent electronic ventricular pacemakers.

METHODS AND RESULTS

Between October 1986 and December 1995, 93 patients with pacemakers underwent pharmacologic stress testing with myocardial perfusion single photon emission computed tomography imaging. Follow-up information on 91 patients (98%) was obtained. Mean follow-up was 5.6 +/- 2.4 years. Previously published clinical and image variables were analyzed for their prognostic significance with regard to cardiac death, cardiac death/nonfatal myocardial infarction, and cardiac death/nonfatal myocardial infarction/late revascularization. The presence of a high-risk scan was a significant predictor of subsequent cardiac death by both univariate (chi 2 = 9.4, P < .001) and multivariate analysis (chi 2 = 6.5, P = .01) after adjustment for clinical score. Clinical score was not a significant predictor of cardiac death.

CONCLUSION

This study demonstrates that pharmacologic stress myocardial perfusion imaging provides significant prognostic information in patients with permanent pacemakers. In this population, pharmacologic stress myocardial perfusion imaging can differentiate patients at high risk of a subsequent cardiac event from those at low risk. These results support the American College of Cardiology/American Heart Association guideline recommendations for pharmacologic stress perfusion imaging in patients with permanent pacemakers.

Impact of Coronary Sinus Lead Position on Biventricular Pacing:

INTRODUCTION

Biventricular pacing is an established treatment for congestive heart failure. Whether the anatomic location of the coronary sinus (CS) lead affects outcomes is unknown. The aim of this study was to evaluate the clinical response and mortality in patients who had transvenous CS leads placed in different anatomic branches for biventricular pacing.

METHODS AND RESULTS

We evaluated 233 consecutive patients with New York Heart Association (NYHA) class III-IV heart failure and ejection fraction <35% who had successful placement of a transvenous left ventricular lead through a CS venous branch. Patients were divided into two groups based on anatomic lead position. Group 1 (n = 66) included leads in the anterior and anterolateral branches. Group 2 (n = 167) included leads in the lateral and posterolateral branches. Postimplant, functional capacity improved from an average 3.1 to 2.7 in group 1 (P = 0.001) and from 3.1 to 2.3 in group 2 (P = 0.001). Left ventricular ejection fraction (LVEF) measured by transthoracic echocardiography did not improve significantly in group 1 (pre-LVEF 18%, post-LVEF 20%; P = NS) but increased significantly from 19% to 27% in group 2 (P = 0.008). Despite the difference in ejection fraction response, the mortality in the two groups after a mean follow-up of 546 days was similar (13.6% group 1 vs 17.9% group 2).

CONCLUSION

Placement of the CS lead in the lateral and posterolateral branches is associated with significant improvement in functional capacity and greater improvement in left ventricular function compared with the anterior CS location. This improvement does not appear to influence mortality.

Thirty years of experience with epicardial pacing in children

Due to underlying cardiovascular anatomy and size, epicardial pacing may be the preferred method of pacing in small children. To assess long-term safety, we reviewed all epicardial pacemakers implanted in children between 1971 and 2001. We found that 122 patients, with a median age of 5.4 years, had a total of 181 pacemakers and 260 electrodes implanted over a total follow-up of 789 patient-years. Of the total, 12 patients died after the first implantation, with one death attributable to dysfunction of the pacemaker. Reintervention was required in 75 patients after 5.0 +/- 3.2 years, due to depletion of the battery in 45 patients (60%), fracture or dysfunction of electrodes in 27 patients (36%), and infection in 3 patients (4%). In univariate analyses, risk factors for reintervention were an approach via a median sternotomy, with a relative risk of 2.3 (p = 0.0087), and an indication for pacing other than atrioventricular block, with a relative risk of 1.7 (p = 0.0314). In multivariate analyses, the approach via the median sternotomy independently predicted the need for reintervention, with a relative risk of 2.1, and 95% confidence intervals from 1.1 to 4.1 (p = 0.0256). The longevity of the second pacemaker and/or its electrode, assessed in 26 patients, was 3.7 +/- 2.6 years, not shorter than the first implantation (p = 0.4037). We conclude that epicardial pacing is a reliable means of achieving permanent pacing in children, with low morbidity and mortality. A substantial proportion, nonetheless, requires reintervention within five years, warranting meticulous follow-up.

Is Mobitz type I atrioventricular block benign in adults?

OBJECTIVE

To assess the need for pacing in adults with chronic Mobitz type I second degree atrioventricular block (Mobitz I).

DESIGN

Prospective study.

SETTING

District general hospital.

PATIENTS

147 subjects aged > or = 20 years (age cohorts 20-44, 45-64, 65-79, and > or = 80) with chronic Mobitz I without second degree Mobitz II or third degree (higher degree) block on entry, seen from 1968 to 1993 and followed up to 30 June 1997. Sixty four had organic heart disease. The presence of symptomatic bradycardia was defined as highly likely in 47 patients (class 1); probable in 14 (class 2); and absent in 86 (class 3).

INTERVENTIONS

Pacemakers were implanted in 90 patients for the following indications: symptoms in 74 and prophylaxis in 16.

MAIN OUTCOME MEASURES

The main outcome measure was death, with conduction deterioration to higher degree block or symptomatic bradycardia the alternative measure.

RESULTS

Five year survival to death was reduced in unpaced patients relative to that expected for the normal population (overall mean (SD) 53.5 (6.7)% v 68.6%, p < 0.001; class 3, 54.4 (7.3)% v 70.1%, p < 0.001). Paced patients fared better than unpaced (overall (mean (SD) five year survival 76.3 (4.5)% v 53.5 (6.7)%, p = 0.0014; class 3, 87.2 (5.4)% v 54.4 (7.3)%, p = 0.020; and organic heart disease, 68.2 (7.6)% v 44.0 (9.9)%, p < or = 0.0014). There were no deaths in the < 45 cohort. Survival to first outcome (main or alternative) was further reduced to 31.7 (5.0)% in 102 patients unpaced initially and 34.2 (5.7)% in class 3. Only the 20-44 cohort and patients with sinus arrhythmia had > 50% survival.

CONCLUSION

Mobitz I block is not usually benign in patients > or = 45 years of age. Pacemaker implantation should be considered, even in the absence of symptomatic bradycardia or organic heart disease.

Pacemaker therapy in very elderly patients: long-term survival and prognostic parameters

BACKGROUND

Permanent pacing is the therapy of choice for treating severe and/or symptomatic bradyarrhythmia. However, augmented life expectancy and increasing health care expenditures have led to questions concerning the routine use of electrotherapy in very elderly patients. This study is aimed at assessing data on the actual number, characteristics, and survival of patients requiring pacing therapy at age > or =80 years.

METHODS

Between 1971 and 2000, 1588 patients aged > or =80 years completed a standardized 6- to 12-month follow-up after pacemaker (PM) implantation, resulting in a total of 5244 patient years. Kaplan-Meier analyses were computed to visualize survival differences in various subgroups and implantation periods.

RESULTS

Today, patients aged > or =80 years account for 32% of all PM implantations. An increasing 5-year survival after PM implantation to the current rate of 66% was found, compared to 37% and 47% in the previous decades. Based on a mean survival time of 8 years, clinical symptoms can be effectively treated with costs of < or =500 dollars per patient per year. Prognostic parameters were the decade of implantation (relative risk [RR] 0.80, CI 0.67-0.96, P < or =.02), a history of presyncope (RR 0.73, CI 0.57-0.95, P < or =.02), and male sex (RR 1.20, CI 1.04-1.40, P < or =.02). However, none of these parameters can be recommended for estimating outcome or for guiding device selection.

CONCLUSIONS

Patients aged > or =80 years account for an increasing portion of PM implantations. Considering the remaining life expectancy of 8 years in these patients, PM therapy is a clinically and economically effective therapeutic option to control bradyarrhythmia-related symptoms.