Baseline characteristics of patients recruited into the CARE-HF study

BACKGROUND

Cardiac resynchronization therapy (CRT) is a promising new treatment for patients with heart failure and cardiac dyssynchrony. The CARE-HF study is a morbidity/mortality trial designed to provide conclusive evidence of the effects of CRT in patients with moderate to severe heart failure.

METHODS

A description of the baseline characteristics of patients randomised in the CARE-HF trial.

RESULTS

813 Patients with predominantly NYHA class III (94%) heart failure were randomised in 82 centres. Their mean age was 65 (interquartile range [IQR] 59 to 72) years, 34% were aged >70 years and 27% were women. Thirty-eight percent of the patients had ischaemic heart disease. Mean heart rate was adequately controlled at 70 (IQR 60 to 78) bpm consistent with the use of beta-blockers. Supine systolic blood pressure was low at 117 (IQR 105 to 130) mm Hg. Eighty-eight percent of patients had a QRS > or =150 ms. Mean LV ejection fraction was 26% (IQR 22 to 29) and end-diastolic dimension was 7.2 (IQR 6.4 to 7.8) cm. Ninety-four percent of patients were receiving loop diuretics, 95% an ACE inhibitor or angiotensin receptor blocker (ARB), 72% a beta-blocker and 56% were taking spironolactone.

CONCLUSIONS

The patients enrolled in CARE-HF had moderately severe heart failure and cardiac dysfunction with evidence of cardiac dyssynchrony. The population appears at high risk of events despite pharmacological therapy and therefore appropriate for a trial of CRT.

Comparative effects of ventricular resynchronization therapy in heart failure patients with or without coronary artery disease

In patients with advanced heart failure, intraventricular conduction delay (IVCD) and left ventricular systolic dysfunction (LVSD), multisite cardiac pacing can be proposed as an additive treatment. The aim of this study was to assess the clinical effectiveness of atrioventricular pacing according to the etiology of LVSD, by comparing the outcome of patients with and without coronary artery disease. Between August 1997 and November 1998, 103 patients were included in the InSync trial and received a biventricular pacemaker and a specifically designed left ventricular pacing lead. Baseline evaluation (12 lead ECG, New York Heart Association Class, quality of life (QOL) and distance walked during the 6 min walk test) was repeated in survival patients at 1, 3, 6 and 12 months after pacemaker implantation. Patients were split in two groups, ischemic (N = 48) and non-ischemic (N = 55), according the result of a recent coronary angiography, the existence of coronary angioplasty or coronary artery bypass or the history of a prior myocardial infarction.

RESULTS

The mortality rate was similar in the two groups with a mean 12 months actuarial survival rate of 78%. Nevertheless, the delay between the death and the pacemaker implantation was significantly higher in the non-ischemic group. A significant reduction in QRS duration and a significant improvement in NYHA class (-1.5). QOL score (-50%) and 6 min walking test (+18%) were observed similarly in the two groups.

CONCLUSION

This study shows that biventricular pacing improves significantly functional status of patients with LVSD, IVCD and advanced heart failure, regardless the etiology of the cardiomyopathy, ischemic or not, without over-mortality in ischemic patients.

Treatment of refractory congestive heart failure by cardiac resynchronization

The contributions of long-term cardiac resynchronization as a supplemental treatment of refractory congestive heart failure have recently been reported. Several completed studies support the validity of this new therapy, capable of improving quality of life as well as increasing exercise capacity. These gains hinge on a careful patient selection, on the proper placement of the leads, particularly that responsible for left ventricular stimulation, and on an individualized patient follow-up. The results obtained thus fat fully justify considering cardiac resynchronization as an additional option in the treatment management of patients refractory to conventional measures. Ongoing studies should help to further defining its impact on morbidity and overall mortality, as well as the potential role for back up defribillator.

The CARE-HF study (CArdiac REsynchronisation in Heart Failure study): rationale, design and end-points

BACKGROUND

Cardiac resynchronisation is a promising new intervention for patients with heart failure, left ventricular systolic dysfunction and ventricular dyssynchrony.

OBJECTIVE

The CARE-HF trial is designed to evaluate the long-term effects of cardiac (atrio-bi-ventricular) resynchronisation on the mortality and morbidity of patients with heart failure due to left ventricular systolic dysfunction already receiving diuretics and optimal medical therapy with ACE inhibitors and beta-blockers (where indicated and tolerated).

METHODS AND RESULTS

Approximately 800 patients will be randomised to device therapy or control and followed for a minimum of 18 months. A pragmatic study design has been chosen that does not attempt to conceal allocation from investigators or patients because it is impossible to guarantee maintenance of blinding for the duration of the study. The end-points committee will adjudicate events in a blinded fashion. Since cardiac resynchronisation may alter other aspects of the management of the patient, as would occur in clinical practice, the study should be considered a comparison of strategies rather than simply of a device. The primary end-point is all-cause mortality or unplanned cardiovascular hospitalisation. The study should complete recruitment during 2002 and report in 2004.

[Treatment of refractory cardiac failure by resynchronization]

Permanent resynchronisation as a complementary treatment of refractory cardiac failure has recently been reported. There have been several publications demonstrating the value of this new therapeutic approach, based on improved quality of life and exercise capacity. The benefits depend on careful patient selection, accurate positioning of the pacing catheters, especially the left ventricular catheter, and on individual follow-up. The present data completely justifies the pursuit of research projects in this new therapeutic domain by using on-going studies to define its impact on mortality.

A pilot experience with permanent biventricular pacing to treat advanced heart failure

BACKGROUND

The prognosis and quality of life of patients with advanced heart failure remain poor. The purpose of this study was to evaluate new nonpharmacologic approaches. Biventricular pacing was proposed in this indication, based on the encouraging results of acute hemodynamics studies.

METHODS

Fifty patients with drug-resistant heart failure (New York Heart Association [NYHA] class III/IV, 16 of 34) were consecutively implanted with biventricular pacemakers. All patients had severe dilated cardiomyopathy and intraventricular conduction delay. Survival, NYHA class, electrocardiogram, echocardiographic data, and exercise tolerance were assessed over a mean follow-up period of 15.4 +/- 10. 2 months.

RESULTS

At the end of follow-up, 55% of patients were alive without heart transplantation or left ventricular assistance device. The mortality rate was significantly lower in class III (12. 5%) than in class IV patients (52.5%). In survivors, biventricular pacing significantly improved symptoms (NYHA class 2.2 +/- 0.5 at follow-up vs 3.7 +/- 0.5 at baseline) and exercise tolerance ((. )VO(2) peak 15.5 +/- 3.4 mL/min per kilogram at follow-up vs 11.1 +/- 3 mL/min per kilogram at baseline).

CONCLUSIONS

Biventricular pacing appears to improve the functional status of patients with dilated cardiomyopathy with advanced heart failure. The technique appears to be attractive as an additive treatment, especially in class III patients. Controlled randomized studies are needed to validate this novel concept.

[Atrio-biventricular electrostimulation in the treatment of congestive heart failure. Case report]

Over the past few years, indications for permanent cardiac pacing have been broadened. Accordingly, American Heart Association and American College of Cardiology included dilated cardiomyopathy, hypertrophic obstructive cardiomyopathy and pacing for prevention of atrial fibrillation into indications for permanent cardiac pacing. Studies have described favourable effect of dual chamber cardiac pacing in congestive heart failure in dilated cardiomyopathy, regardless of etiology. In the past two years, even more beneficial effect was associated with multisite, biventricular cardiac pacing. On the basis of the reported results, a multisite pacemaker InSync was implanted to a patient with dilated cardiomyopathy (NYHA class IV), who was also on the list for heart transplantation, and who fulfilled other criteria for implantation of multisite pacemaker. During the eleven-month follow-up, functional improvement, better 6-minute walking test and enhanced quality of life of the patient were observed, which is in accordance with the literature data.

Junctional rhythm during slow pathway radiofrequency ablation in patients with atrioventricular nodal reentrant tachycardia: beat-to-beat analysis and its prognostic value in relation to electrophysiologic and anatomic parameters

INTRODUCTION

Junctional rhythm usually is considered a sensitive but nonspecific marker of successful ablation of the slow pathway in AV nodal reentrant tachycardia. Nevertheless, this junctional rhythm has been little studied, and its relations to recognized predictors of successful radiofrequency (RF) application were never established in any study.

METHODS AND RESULTS

Thirty-nine patients underwent RF ablation of the slow pathway for AV nodal reentrant tachycardia. Ninety RF applications were delivered, and each ablation site was determined using three different fluoroscopic projections. Six anatomic zones were defined from low posterior septum to the site of distal His-bundle recording (P1, P2, M1, M2, A1, and A2). Characteristics of junctional rhythm during RF applications were analyzed. Atrial electrogram characteristics at the ablation sites also were studied. All patients had successful slow pathway ablation, without any complication. The ablation sites were located as follows: 41 at P1, 26 at P2, 20 at M1, and 3 in M2. Forty RF applications were successful: 14 of 41 attempts at P1, 7 of 26 at P2, 16 of 20 at M1, and 3 of 3 at M2. Mid-septal ablation site (M1 and M2) was associated with higher occurrence of junctional rhythm (P < 0.0001), earlier first junctional beat (P = 0.008), and earlier occurrence of the longest junctional burst (P = 0.03) compared with posterior ablation site (P1 and P2). The combination of a mid-septal ablation site and a first junctional beat occurring < or = 3 seconds after onset of RF application identified successful RF application with 100% accuracy. Using multivariate analysis, the ablation site, duration of atrial electrogram (including slow pathway potential when present), and occurrence of junctional rhythm were independent predictors of success.

CONCLUSION

Successful slow pathway ablation depends on many factors. Junctional rhythm characteristics are related to the site of RF delivery and can be helpful in assessing successful slow pathway ablation.

Significant improvement of quality of life following atrioventricular synchronous pacing in patients with hypertrophic obstructive cardiomyopathy. Data from 1 year of follow-up. PIC study group. Pacing In Cardiomyopathy

AIMS

Atrioventricular synchronous pacing exerts beneficial effects, including reduction of left ventricular outflow tract gradients, in patients with hypertrophic obstructive cardiomyopathy. The Pacing in Cardiomyopathy study was initiated to explore the effects of pacing in a double-blind randomized crossover fashion. The aims were to ascertain the beneficial effects of pacing in a controlled study and to rule out a placebo effect by pacing. This paper deals with the outcome of pacing on quality of life during 1 year of follow-up.

METHODS

Quality of life was evaluated with the Karolinska questionnaire, validated for patients paced for bradyarrhythmias and ischaemic heart disease. Drug-refractory patients with hypertrophic obstructive cardiomyopathy were recruited for the study and after a temporary pacing procedure implanted with permanent pacemakers. Patients were randomized to two study arms defining the sequence of pacemaker programming. In one arm the pacemaker was inactive, in the other active. After 3 months the pacemaker was reprogrammed to the alternate mode and a further 3 months followed. After this period subsequent pacemaker programming corresponded to the mode preferred by the patient. A last assessment was made 1 year after baseline examinations.

RESULTS

Eighty patients completed the first crossover period and 75 completed the full 1 year of follow-up. Active pacing induced significant quality of life improvements, in the order of 9-44%, regardless of programming sequence. Discontinuation of pacing after a first active period resulted in the return of symptoms. Fourteen patients requested early reprogramming after having been programmed to inactive pacing after a first period of active pacing. Seventy-six patients preferred active pacing after the crossover period. A further 6 months of pacing induced progressive improvement in symptoms already favourably influenced.

CONCLUSION

Atrioventricular synchronous pacing has a profound beneficial effect on most domains of quality of life in patients with hypertrophic obstructive cardiomyopathy refractory to drug treatment.

Clinical progress after randomized on/off pacemaker treatment for hypertrophic obstructive cardiomyopathy. Pacing in Cardiomyopathy (PIC) Study Group

BACKGROUND

The therapeutic options for hypertrophic obstructive cardiomyopathy (HOCM) classically include medical treatment with beta-blockers and calcium antagonists or myectomy-myotomy as a surgical possibility for refractory cases. The observation that pacemaker activation of the heart in HOCM reduces the subaortic gradient is well known but less well investigated.

METHODS

Eighty-three patients (33 female and 50 male) mean age 53 (18-82) years, with symptoms refractory to drug treatment and a resting gradient above 30 mmHg, who responded favourably to temporary pacing, were included in this prospective study and had a pacemaker (DDD) implanted. After an initial double-blind crossover phase of 6 months, patients were reinvestigated at 12 months and followed for a mean of 36 months.

RESULTS

As observed during a screening investigation, the obstruction was significantly reduced from 72 +/- 35 mmHg to 29 +/- 24 mmHg (P < 0.01) when the pacemaker was on, while no major effect was seen during the sham phase. The effect was persistent at 1 year with a remaining resting gradient of 28 +/- 24 mmHg. In parallel, we documented an improvement in functional capacity, according to the NYHA classification and by quality of life analysis, and a significant improvement in dyspnoea and angina. Exercise on treadmill improved only in patients with reduced initial tolerance (< 8 min). During the mean follow-up of 36 months, 65 patients remained on pacing alone, with eight patients having additional AV-node ablation and five patients finally having surgery.

CONCLUSION

This controlled multicentre study shows that pacemaker treatment is an option for HOCM patients; it is inoffensive and does not exclude alternative methods, but satisfies 79% of patients beyond 3 years.

Effects of permanent dual-chamber pacing on mitral regurgitation in hypertrophic obstructive cardiomyopathy

AIMS

To assess the effects of chronic dual-chamber pacing on mitral regurgitation in hypertrophic obstructive cardiomyopathy.

METHODS AND RESULTS

Twenty-three patients with hypertrophic obstructive cardiomyopathy and mitral regurgitation. treated with DDD pacing for 16 +/- 14 months, were included in the study. Mitral regurgitation was assessed by Doppler-echocardiography using semi-quantitative analysis (grades I-IV) and by measuring the maximum regurgitant jet area/left atrial area ratio. At the end of follow-up, DDD pacing reduced the outflow gradient from 93 +/- 37 mmHg to 31 +/- 30 mmHg (P<0.0001). Nine of the 14 patients who initially had > or =grade II mitral regurgitation improved by at least one grade, two of them exhibiting dramatic improvement (from grade IV and III to grade I). The regurgitant jet area/left atrial area ratio was reduced with DDD pacing from 20 +/- 13% to 11 +/- 6% (P<0.0001). Patients who had significant mitral regurgitation despite pacing were those whose outflow gradient remained high or those with mitral valve organic abnormalities (mitral annulus calcification or mitral valve prolapse). In the absence of organic abnormalities other than leaflet elongation, there was a significant correlation between the gradient value achieved with DDD pacing and the extent of mitral regurgitation (P<0.05).

CONCLUSION

In the absence of organic mitral valve abnormalities, DDD pacing reduces in parallel mitral regurgitation and left ventricular outflow gradient. In such patients therefore, significant mitral regurgitation is not a contraindication to pacing.

Acute hemodynamic effects of biventricular DDD pacing in patients with end-stage heart failure

OBJECTIVES

The aim of this study was to assess the potential acute benefit of multisite cardiac pacing with optimized atrioventricular synchrony and simultaneous biventricular pacing in patients with drug-refractory congestive heart failure (CHF).

BACKGROUND

Prognosis and quality of life in severe CHF are poor. Various nonpharmacological therapies have been evaluated but are restricted in their effectiveness and applications. In the early 1990s, dual chamber pacing (DDD) pacing was proposed as primary treatment of refractory CHF but results were controversial. Recently, tests to evaluate the effect of simultaneous pacing of both ventricles have elicited a significant improvement of cardiac performance.

METHODS

Acute hemodynamic study was conducted in 18 patients with severe CHF (New York Heart Association class III and IV) and major intraventricular conduction block (IVCB) (QRS duration = 170+/-37 ms). Using a Swan-Ganz catheter, pulmonary artery pressure, pulmonary capillary wedge pressure (PCWP) and cardiac index (CI) were measured in different pacing configurations: atrial pacing (AAI) mode, used as reference, single-site right ventricular DDD pacing and biventricular pacing with the right ventricular lead placed either at the apex or at the outflow tract.

RESULTS

The CI was significantly increased by biventricular pacing in comparison with AAI or right ventricular (RV). DDD pacing (2.7+/-0.7 vs. 2+/-0.5 and 2.4+/-0.6 l/min/m2, p < 0.001). The PCWP also decreased significantly during biventricular pacing, compared with AAI (22+/-8 vs. 27+/-9 mm Hg; p < 0.001).

CONCLUSIONS

This acute hemodynamic study demonstrated that biventricular DDD pacing may significantly improve cardiac performance in patients with IVCB and with severe heart failure, in comparison with intrinsic conduction and single-site RV DDD pacing.

Multisite pacing as a supplemental treatment of congestive heart failure: preliminary results of the Medtronic Inc. InSync Study

This report describes the initial results of the "InSync" study, a European and Canadian multicenter trial that examines the safety and efficacy of a multisite pacemaker (Medtronic InSync) and of left ventricular pacing leads (Medtronic 2187 and 2188) implanted via a cardiac vein as a supplemental treatment of refractory congestive heart failure. Over a 10-month period, the system was implanted successfully in 68 of the 81 (84%) patients who had been enrolled in the study. The 68 patients were, on average, 66 +/- 10 years old, had a mean left ventricular ejection fraction (LVEF) = 21% +/- 9%, and 63% were in NYHA functional Class III and 37% were in Class IV. No system implant related complication occurred. During follow-up, 7 of 10 patients who exited the study had died, 4 suddenly. There was a clinical benefit among surviving patients, which was corroborated by a significant improvement in NYHA functional class and in the Minnesota Living with Heart Failure Quality of Life Questionnaire Score (MLS) and by a longer distance covered during a 6-minute walk test. This clinical improvement was associated with a significant narrowing of the paced QRS complex during biventricular pacing, a significant decrease in the interventricular mechanical delay, and a trend towards an increase in the duration of ventricular filling. These encouraging preliminary results confirm the feasibility and reliability of this new multisite pacing system in the management of dilated cardiomyopathy and support the continuation of further evaluations of this complementary treatment of refractory congestive heart failure.

Reduction in energy pacing thresholds by overlapping biphasic stimulation versus conventional bipolar pacing

Overlapping biphasic (OLBI) stimulation is a new pacing waveform consisting of two simultaneous monophasic pulses of opposite polarities applied to a bipolar electrode. The goal of this prospective study was to compare, using conventional pacing leads, the acute energy pacing thresholds, measured at 0.5-ms pulse duration, associated with bipolar versus OLBI (mode 7 and mode 8) pulse delivery.

RESULTS

Thirty one leads were tested in 20 patients. Of these leads, 7 (23%) were implanted chronically, 12 (39%) were in atrial positions, and 19 (61%) in ventricular positions. Energy pacing thresholds were significantly lower (-25.6 +/- 25.6%, P = 0.005) in OLBI mode 8 (1.30 +/- 3.96 microJ) compared to bipolar (1.55 +/- 4.37 microJ) pacing, regardless of the pacing site or length of service of the leads. In contrast, OLBI mode 7, which has an anodal component, at the tip electrode was associated with higher energy pacing thresholds (3.65 +/- 6.48 microJ; +358.3 +/- 219.4%, P = 0.002).

CONCLUSIONS

Mode 8 OLBI pacing is associated with lower acute energy pacing thresholds when used with bipolar leads in contact with the myocardium. OLBI pacing may increase pacemaker longevity by reducing long-term energy consumption.

Reliability of an automatic sensing test with beat-to-beat display of the signal amplitude

In contrast to testing of the capture threshold, the reliability of sensing tests has been little studied. This study was performed to test the automatic sensing algorithm included in the Biotronik pacing systems. The automatic measurements made by the devices were compared with the direct manual measurements made of 271 atrial (72%) or ventricular (28%) electrograms recorded in ten patients. A high correlation (r = 0.995, P < 0.0001) was found between the two types of measurements. The use of this function should facilitate the verification of accurate sensing during the long-term follow-up of pacemaker patients, and offers a tool to analyze the variations in amplitude of intracardiac signals.

Permanent left ventricular pacing with transvenous leads inserted into the coronary veins

This paper describes a preliminary experiment-conducted jointly by 2 centers-of permanent left ventricular pacing using leads inserted by the transvenous route and through the coronary sinus into the cardiac veins of the left ventricle free wall. The aim was to obtain permanent biventricular pacing in a totally endocavitary configuration in patients with severe LV dysfunction and drug-refractory heart failure. Two types of leads were used: nonspecific unipolar leads at the beginning of the experiment, followed by leads specifically designed to be used in the coronary sinus in a second step. The electrode could be fitted in an adequate location in 35 of the 47 patients (75.4%), with a 1.15 +/- 0.7 V acute pacing threshold and 11.8 +/- 5.7 mV R wave amplitude. The success rate was significantly higher with the specific electrodes (81.8% vs 53.3%, p < 0.001). The pacing and sensing thresholds upon implantation were not influenced by the type of lead or by the localization of the cardiac vein that was catheterized (great cardiac vein, lateral vein, postero-lateral or posterior vein, mid cardiac vein). In contrast, the pacing threshold was significantly lower (0.8 +/- 0.2 vs 1.8 +/- 0.8 V; p = 0.002) and the R wave amplitude tended to be greater (13.1 +/- 4.5 mV vs 9.3 +/- 6.5 mV; p = 0.07) when the tip electrode could be inserted distally into the vein, by comparison with a proximal site near the ostium. At the end of follow-up (10.2 +/- 8.7 months), 34 out of the 35 leads were still fully functional, with a chronic pacing threshold of 1.8 +/- 0.7 V and a R wave amplitude of 10.7 +/- 6 mV. To conclude, permanent LV pacing via the transvenous route is possible in most patients, with excellent safety and long-term results.