Prevalence of potential candidates for biventricular pacing among patients with known coronary artery disease: a prospective registry from a single center

Clinical characteristics and value in early reperfusion therapy for new onset right bundle branch block in patients with acute myocardial infarction

The value of the right bundle branch block (RBBB) in the treatment of acute myocardial infarction remains unclear. Studies on the RBBB may significantly influence the treatment of acute myocardial infarction. A total of 845 patients with acute myocardial infarction who underwent primary coronary angiography at Henan Provincial People's Hospital were analyzed. Higher peak enzyme levels, a higher ratio of Killip ≥II and closer proximal occlusion of infarct-related artery (IRA) were observed in patients with RBBB compared with those without. The ratio of TIMI flow 0/1 of IRA and ratio of received primary percutaneous coronary intervention (PCI) to IRA in the RBBB group were significantly higher compared with those in the left (L) BBB or no BBB groups. The in-hospital major adverse cardiac events (MACE) incidence in the RBBB group was higher compared with that in the no BBB group, but there was no significant difference between the RBBB and LBBB groups. Logistic regression revealed that proximal occlusion and TIMI flow 0/1 of IRA were predictive factors of RBBB. Cox regression analysis identified RBBB [risk ratio (RR), 4.682; P<0.001] and LBBB (RR, 3.687; P<0.001) as independent predictors of in-hospital MACE. The cumulative one-year survival rate in the RBBB group was significantly lower than those in the no BBB group (P<0.05) and the LBBB group (P<0.05). Similar to the guidelines regarding new onset of LBBB, new onset RBBB should be considered as a standard indicator for reperfusion therapy; as RBBB is associated with more severe symptoms, and higher incidents of complete occlusion of IRA and primary PCI treatment compared with LBBB.

Left ventricular mechanical dyssynchrony in patients with impaired left ventricular function undergoing gated SPECT myocardial perfusion imaging

INTRODUCTION

Gated SPECT myocardial perfusion imaging (MPI) has been used to quantify mechanical dyssynchrony. Mechanical dyssynchrony appears to be related to response to cardiac resynchronization therapy.

OBJECTIVE

To evaluate the presence and predictors of mechanical dyssynchrony in patients with impaired left ventricular function (LVEF) ≤50%.

METHODS

The study included 143 consecutive patients referred for gated SPECT MPI with LVEF ≤50%. Gated SPECT MPI was performed according to a stress/rest protocol acquiring images with Tc 99m-tetrofosmin. Emory Cardiac Toolbox software was used for phase analysis and a standard deviation (SD) ≥43° was considered to indicate mechanical dyssynchrony.

RESULTS

Mechanical dyssynchrony was present in 53.1% of the patients. Its predictors were diabetes (OR 2.0, p≤0.05), summed stress score (OR 1.1, p≤0.0005), summed rest score (OR 1.1, p≤0.0001), end-diastolic volume (OR 1.0, p≤0.0001), LVEF (OR 0.9, p≤0.0001), LVEF ≤35% (OR 3.1, p≤0.005) and LVEF ≤35% and QRS ≥120 ms (OR 3.5, p≤0.05). In this study QRS width and QRS ≥120 ms were not predictors of mechanical dyssynchrony.

CONCLUSIONS

Myocardial perfusion imaging can be used to assess mechanical dyssynchrony. In patients with impaired ventricular function mechanical dyssynchrony was highly prevalent and was related to parameters of left ventricular function and perfusion.

The cost of medical management in advanced heart failure during the final two years of life

OBJECTIVE

To examine patterns of resource use and the cost of care for patients with advanced heart failure treated with medical management (MM) during the final 2 years of life.

METHODS AND RESULTS

The study population (n=47, mean age 70.4 years+/-7.06) included patients randomized to the MM arm of the Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure trial. Inpatient and outpatient use data were obtained from the clinical dataset and Centers for Medicare and Medicaid Services (beginning January 1, 1998). Cost and resource use were tracked from the date of death (t(d)) backward in 3-month intervals (eg, t(d-1), t(d-2)). In the primary analysis, costs were summed across intervals. The mean cost of MM in the final 2 years of life was $156,169, with 50.5% ($78,880.39) expended in the final 6 months. The mean quarterly cost increased (P < .01) 4.9-fold from t(d-8) ($8,816 +/- $14,270) to t(d-1) ($42,836 +/- $41,407). The number of inpatient days increased (P < .01) 6.6-fold from 3.8+/-4.7 days to 22.2+/-23.5 days during the same time intervals.

CONCLUSION

This current economic analysis extends on previous findings by demonstrating that medical therapy in advanced and end-stage heart failure is associated with significant costs and resource consumption; these costs and resource consumption increase significantly as death approaches.

How many patients with heart failure are eligible for cardiac resynchronization? Insights from two prospective cohorts

AIMS

To determine what proportion of patients with heart failure are eligible for cardiac resynchronization therapy (CRT).

METHODS AND RESULTS

Eligibility criteria from the trials establishing the efficacy of CRT were applied to two prospective cohorts: the first enrolled patients with newly diagnosed heart failure discharged from 103 hospitals between April 1999 and March 2001 ('the hospital discharge cohort'); the second enrolled patients seen in a specialized clinic between August 2003 and January 2004 ('the specialty clinic cohort'). In the hospital discharge cohort, 73 patients (3% of the 2640 patients with ischaemic or dilated cardiomyopathy and 1% of all 9096 patients with heart failure discharged alive) met trial eligibility criteria: LVEF< or =0.35, QRS > or =120 ms, sinus rhythm, and NYHA class III or IV symptoms despite the treatment with ACE-inhibitor/angiotensin receptor blocker and beta-blocker. In the specialty clinic cohort, 54 patients (21% of the 263 patients with ischaemic or dilated cardiomyopathy and 17% of all 309 patients with heart failure) met these criteria. If persistent symptoms despite taking spironolactone were required for CRT eligibility, then the proportions qualifying dropped to 1% in the hospital discharge cohort and 18% in the specialty clinic cohort.

CONCLUSION

Few heart failure patients meet trial eligibility criteria for CRT.

Device Therapy in the Management of Congestive Heart Failure

Despite significant advancements in the treatment of heart failure over the past 2 decades, this patient population is still subject to considerably high morbidity and mortality rates. In recent years, the field of device therapy as adjunctive treatment to the medical management of congestive heart failure has grown in the wake of the large number of randomized trials that have demonstrated the safety and efficacy of these devices. The implantable defibrillator currently represents the standard of care in certain segments of the heart failure population, even in those without a prior arrhythmic event. Biventricular pacing systems appear to have a role in heart failure patients with prolongation of their QRS duration in improving ventricular performance and symptoms, if not mortality. Last, the shortage of organs available for orthotopic transplant has heightened interest in using ventricular-assist devices as destination therapy, and although there is evidence for the feasibility for this approach at the current time, there is a next generation of devices that appear even more promising.

Proportion of patients in a congestive heart failure care management program meeting criteria for cardiac resynchronization therapy

Among 1,138 patients in our congestive heart failure care management database, 37 (3.2%) met guideline criteria for cardiac resynchronization therapy. Advancing age was a predictor of prolonged QRS duration in this population, but gender, ejection fraction (EF) and cause of heart failure were not. There was a trend toward an inverse correlation between QRS duration and EF among patients with EF < or = 35%.

Cardiac Resynchronization Therapy:. Device-Based Medicine for Heart Failure

Cardiac resynchronization therapy (CRT) or biventricular pacing is a novel adjunctive therapy for patients with advanced heart failure (HF). Many patients with severe HF have a left bundle branch block or an intraventricular conduction delay, with up to 25% of patients with a QRS > 120 ms, resulting in significant left ventricular (LV) dyssynchrony and a high mortality rate. The efficacy of CRT is based on the reduction in the conduction delay between the two ventricles and optimization of the ejection fraction, decrement in mitral regurgitation, LV remodeling, thus resulting in symptom improvement. Cardiac resynchronization therapy can be achieved both transvenously using a coronary sinus branch, or epicardially. Clinical trials have demonstrated a significant improvement in the NYHA class and the exercise capacity as well as a marked reduction in the hospitalization rate. More recently, the COMPANION trial showed a 43% reduction in a composite endpoint of all-cause mortality and hospitalization in the group receiving a CRT device in combination with an implantable cardiac defibrillator (ICD). Thus, management of patients with reduced LV function, wide QRS, and symptomatic refractory HF, despite optimal drug therapy, should include CRT as an option. The adjunct of an ICD combined with CRT should be considered if the LV ejection fraction (ischemic cardiomyopathy) is <30%. There are still significant unanswered questions regarding the nonresponder population and the role of tissue Doppler imaging techniques, the impact of CRT on total mortality and CRT in dilated cardiomyopathy or chronic atrial fibrillation. The use CRT postoperatively or at time of cardiac surgery, as well as new epicardial approaches using a thoracoscopic approach or robotically assisted surgery in patients not suitable for coronary vein leads are challenging topics to address in the years to come.

Cardiac resynchronization by pacing: an electrical treatment of heart failure

Various modalities of cardiac pacing have been proposed in the past to improve hemodynamics, either directly or indirectly. Some of these are conventional ways of cardiac stimulation, others such as biventricular or left ventricular pacing, represent dedicated pacing techniques. Left ventricular and biventricular pacing are successfully applied in those patients with congestive heart failure who have conduction disturbances (i.e. left bundle branch block) as they correct the ensuing intra- and interventricular dyssynchrony. This is the reason why these pacing modalities are described as cardiac resynchronization therapy. According to the results of a series of studies, the cardiac resynchronization therapy seems to have a favourable clinical impact in terms of quality of life, morbidity and hospitalization rate. On-going and future studies should assess the impact of resynchronization therapy on overall mortality and its cost-effectiveness profile in specific subgroups of patients. Other open issues regard (i) the convenience of using biventricular pacing as a pacing-alone therapy or in combination with ventricular defibrillation capability, especially for potential candidates to heart transplantation, and (ii) the ways to identify properly the responders to resynchronization therapy.

Advances in devices for cardiac resynchronization in heart failure

Patients with advanced heart failure have a high mortality and morbidity despite medical therapy. Depending on the underlying heart disease and severity of heart failure, 3.7 to 52.8% of patients have a QRS complex > or =120 ms who may have interventricular and intraventricular dyssynchrony correctible by cardiac resynchronization therapy (CRT). The latter is usually achieved with biventricular pacing, with the left ventricular lead placed in a tributary of the coronary sinus (CS), with a reported success rate between 88-92%. The technical advances for implantation include preformed guide sheaths to cannulate the CS, over the wire leads with passive fixation mechanism, and surgical placement methods. Device-specific CRT features include optimizing heart failure through insurance of a high percentage of pacing, heart failure monitoring, atrioventricular and interventricular timing, and avoiding double ventricular sensing. Furthermore, arrhythmic co-morbidities of heart failure such as atrial fibrillation and ventricular tachyarrhythmias can also be managed. Recent prospective trials suggest that there is a 30% reduction in heart failure hospitalization with CRT, and preliminary results suggest a survival benefit with CRT and implantable cardioverter defibrillator over optimal medical therapy.

Potential Candidates for Cardiac Resynchronization Therapy in Japanese Patients With Idiopathic Dilated Cardiomyopathy-A Niigata Multicenter Study of DCM-

BACKGROUND

The purpose of this study was to assess the candidates suitable for cardiac resynchronization therapy (CRT) and to examine the significance of the QRS duration in Japanese patients with idiopathic dilated cardiomyopathy (DCM).

METHODS AND RESULTS

The study population consisted of 357 patients. The selection criteria for candidates suitable for CRT were QRS duration =130 ms, left ventricular ejection fraction (LVEF) =35% and New York Heart Association (NYHA) functional class III or IV by ACC/AHA/NASPE 2002 guidelines. We divided the study population into 2 groups: group A with a QRS duration <130 ms, and group B with a QRS duration =130 ms. In 25 of the 375 patients (7.0%), all the criteria were fulfilled. Group B had a significantly larger left ventricular diameter end-diastole and end-systole than group A (P<0.0001). Group B had a lower LVEF (P<0.0001). There was a fair inverse correlation (r=-0.58, P<0.0001) between the length of the QRS duration and LVEF.

CONCLUSION

Approximately 7% of the Japanese patients with DCM are CRT candidates. In the present study, we found that prolonged QRS duration was associated with poor systolic function.

How many patients with dilated cardiomyopathy may potentially benefit from cardiac resynchronization therapy?

The clinical and electrocardiographic Marburg Cardiomyopathy database was analyzed to identify potential candidates for cardiac resynchronization therapy (CRT) with biventricular or left ventricular pacing among 566 patients with dilated cardiomyopathy (DCM). All of the following restrictive selection criteria were fulfilled by 38 patients (7%): NYHA functional class > or = 3 (n = 193, 34%), left ventricular ejection fraction (LVEF) < 30% (n = 238, 42%), sinus rhythm (n = 437, 77%), left bundle branch block (LBBB, n = 142, 25%), and QRS duration > or = 150 ms (n = 136, 24%). In 78 of the 566 patients (14%) all of the following less restrictive selection criteria were fulfilled: NYHA functional class > or = 3 (n = 193, 34%), LVEF < 35% in presence of any underlying rhythm (n = 326, 58%), QRS duration > or = 120 ms with right or left bundle branch block (n = 223, 39%). Thus, between 7% and 14% of patients with DCM were candidates for CRT depending on the application of strict versus less restrictive selection criteria.

Biventricular pacing in heart failure: update on results from clinical trials

Biventricular pacing or resynchronisation therapy is a non-pharmacological therapy for patients with chronic heart failure. Since being originally described in 1994, biventricular pacing has become a subject of intense interest and investigation. This review analyses the results reported in observational series and randomised trials, and seeks to answer two questions. If it works, why does it work? Which heart failure patients will it benefit?