The Pacing Therapies for Congestive Heart Failure (PATH-CHF) Study - PATH-CHF

Description:

This study sought to evaluate the clinical effect of hemodynamically optimized univentricular or biventricular pacing compared to no pacing in patients with advanced congestive heart failure.

Hypothesis:

Pacing would lead to improved clinical benefit in patients with congestive heart failure when compared to no pacing.

Study Design

Study Design:

Patients Enrolled: 42 (25 analyzed)
NYHA Class: III, IV
Mean Follow Up: 6 Months
Mean Patient Age: 47-67
Female: 48
Mean Ejection Fraction: LVEF was 22% +/- 7% (mean +/- SD) at baseline and 26% +/- 9 (mean +/- SD) after 6 months.

Patient Populations:

1. Dilated cardiomyopathy of either ischemic or idiopathic etiology 2. NYHA Class III or IV 3. Sinus rhythm >55 bpm 4. QRS complex duration >120 msec in at least 2 surface ECG leads 5. PR interval >150 msec

Exclusions:

1. Major cardiovascular event such as MI, CABG or major surgical procedure within 6 months of study entry 2. Primary valve dysfunction or valve repair or replacement 3. Heart failure equiring inotropic medication 4. Unexplained syncope 5. Sustained ventricular arrhythmias requiring antiarrhythmic medications or an implantable cardioverter defibrillator 6. Atrial fibrillation or flutter within the last 6 months 7. Sinus node dysfunction 8. Atrioventricular block greater than Mobitz I or arrhythmias requiring pacemaker implantation 9. Hypertrophic obstructive cardiomyopathy 10. Life expectancy <6 months 11. Clinically significant renal or hepatic disease, uncontrolled diabetes or chronic alcoholism

Primary Endpoints:

Oxygen consumption at peak exercise and at anerobic threshold during cardiopulmonary exercise test and 6-minute walk distance

Secondary Endpoints:

Changes in New York Heart Association dunctional class, hospitalization frequency and quality of life.

Drug/Procedures Used:

Patients received an implantable pacemaker system with te ability to switch from univentricular to biventricular pacing capability. At the time of the initiation of this study, this necessitated implantation of two pulse generators. The patient was then randomized to univentricular or biventricular pacing. The optimal pacing site and AV delay when pacing the right, left, or right and left ventricles were determined using a computer generated protocol. Patients were paced for 4 weeks followed by 4 weeks without pacing, and finally crossed over the the other modality (biventricular or univentricular) of pacing for 4 weeks. Quality of life was assessed using the Minnesota Living with Heart Failure Questionnaire. Changes in ejection fraction, chamber sizes and filling pattern were obtained by echocardiography.

Concomitant Medications:

Of the 25 patients evaluated, 96% receive angiotensin converting enzyme inhibitors, 88% received digitalis, and 44% received nitrates. 14 patients were initially taking beta-blockers. At 6 months, 9 had constant dosage. The dose was reduced in two and increased in three after 6 months. Of the 24 patients taking diuretics, the dosage was increased in two, decreased in 10 and kept constant in 12.

Principal Findings:

An analysis of echocardigraphic data from 25 of the 42 enrolled patients showed that after 6 months of pacing, the left ventricular end-diastolic and end-systolic diameters (LVEDD and LVESD, respectively) were significantly reduced (LVEDD from 71 ± 10 to 68 ± 11 mm, p=0.027; LVESD from 63 ± 11 to 58 ± 11 mm, p=0.007). LV end-diastolic and end-systolic volumes were also reduced(LVEDV from 253 ± 83 to 227 ± 112 ml, P = 0.017; LVESV from 202 ± 79 to 174 ± 101 ml, p=0.009), and the ejection fraction was significantly increased (from 22 ± 7% to 26 ± 9%, p=0.03). Those patients who did not experience LV volume reduction had significantly higher baseline LVEDVs compared with those who did (351 ± 52 vs. 234 ± 74 ml, p=0.018).

Interpretation:

In patients with advanced heart failure and increased QRS duration, there is a decrease in LV dimensions at 6 months in some patients. The small sample size, slected population and lack of a control group limit the generalizability of these findings and clinical applicability to the heart failure population at large.

References:

1. Auricchio A, Stellbrink C, Sack S, Block M, Vogt J, Bakker P, Mortensen P, Klein H. The Pacing Therapies for Congestive Heart Failure (PATH-CHF) study: rationale, design, and endpoints of a prospective randomized multicenter study.Am J Cardiol 1999 Mar 11;83(5B):130D-135D. 2. The PATH-CHF (PAcing THerapies in Congestive Heart Failure) Investigators; CPI Guidant Congestive Heart Failure Research Group. Impact of cardiac resynchronization therapy using hemodynamically optimized pacing on left ventricular remodeling in patients with congestive heart failure and ventricular conduction disturbances. J Am Coll Cardiol 2001 Dec;38(7):1957-65.

Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Implantable Devices, Acute Heart Failure, Echocardiography/Ultrasound

Keywords: Cardiac Pacing, Artificial, Quality of Life, Heart Failure, Electrocardiography, Questionnaires, Cardiomyopathy, Dilated, Cardiac Resynchronization Therapy, Echocardiography


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