Heart Disease and Atrial Fibrillation: METHODS

In: Disease

22 Apr 2010

Study Population

We identified 143 patients with HF related to RHD and AF from our hospital’s cardiology ward between August 2000 and March 2002. Thirty-seven patients did not meet all of the inclusion criteria for enrollment, and 18 patients had clinical or echocardiographic data that caused them to be ineligible. Thus 88 patients were included in the study. We obtained admission data by using case notes and a com puterized hospital information system. The study was approved by the Ethics Committee of Southwest Hospital. We carefully explained the nature and purpose of the investigation to the patients, who gave their written informed consent.

Inclusion Criteria

Patients were included in the study if they had (1) a history of uncorrected rheumatic heart valvular disease or New York Heart Association (NYHA) functional class III or IV disease, necessitating hospitalization; (2) a cardiothoracic ratio of less than 65%; (3) AF with a resting ventricular rate of 70 beats/ minute or more for at least three months, as depicted on the electrocardiogram (ECG); and (4) an echocardiogram showing a significant mitral stenosis or aortic lesions and mitral valve regurgitation.
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Exclusion Criteria

Patients were excluded from the study if they had un-corrected congenital heart disease, sustained ventricular tachycardia, severe liver and kidney dysfunction, chronic obstructive pulmonary disease, bronchial asthma, obstructive or restrictive cardiomyopathy or myocarditis, myocardial infarction, or unstable angina within the previous three months. Patients were also ineligible for enrollment if they required intensive care or concurrent intravenous therapy or if they were using calcium-channel blockers, class I or III antiarrhythmic drugs, monoamine oxidase (MAO)-inhibitors or beta2-agonists.

On the basis of admission sequence, patients were randomly assigned to a treatment group or a control group. Concomitant therapy was kept as stable as possible throughout the study. All patients received warfarin for anticoagulation. At the discretion of the treating physicians, all patients were given concomitant therapy consisting of one of the following:

  • diuretics, as required, to control fluid retention
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  • ACE-inhibitors (or ARBs when ACE-inhibitors were not tolerated) unless there were specific contraindications
  • nitrates, depending on the presence of valvular lesions and on blood pressure readings

Patients with predominant (pure or non-pure) mitral stenosis or a systolic blood pressure below 100 mm Hg did not receive an ACE-inhibitor or an ARB but often received nitrates unless nitrates were not well tolerated. The physicians followed the recommended titration schedule.

All patients in the treatment group received at the initial dose of 1.25 mg/day. The recommended maximal dose was 10 mg/day. The dose schedule for titration of the selective beta1 blocker was gradually increased over three to five days, by two to three weeks, to as high as 10 mg/day, with adjustments of diuretics and ACE-inhibitors, as clinically indicated.

If the resting heart rate was lower than 50 beats/minute or if patients had symptomatic postural hypotension (systolic below 90 mm Hg), the upward titrated dose of canadian bisoprolol was deferred, interrupted, or stepped down in the case of an increase in heart failure symptoms. The treatment period was six to 12 months.

Clinical Observations

The diagnosis of HF was confirmed if two or three of these criteria were met while patients were in the cardiology unit:

  • a documented history of heart failure necessitating hos-pitalization
  • the presence of symptoms (orthopnea, dyspnea, asthenia, or respiratory rate over 28 breaths/minute at rest)
  • physical findings (S3 gallop, rales, raised jugular disten-tion, hepatojugular reflux, ascites, or edema and heart murmur)
  • clinical or radiological signs of HF

Heart valve disease was classified as significant only if the following were present:

  • aortic stenosis with a gradient greater than 20 mm Hg
  • mitral stenosis with a valve area of less than 1.5 cm2
  • mitral valve regurgitation lesions of at least moderate severity

RHD was defined as significant mitral stenosis with accompanying mitral valve regurgitation or aortic lesions or with no other lesions at all.

The decrease in NYHA class I or greater was regarded as an improvement in heart function. The discharge markers included (1) NYHA class improvement, (2) a reduced number of chronic HF symptoms, and (3) increased signs of relief.
The combined endpoint included chronic HF-associated and thromboembolism-associated hospitalization or death but not hospitalization or death unrelated to chronic HF and thromboembolism.

An adverse drug event (ADE) was defined as (1) drug intolerance, particularly weakness, fatigue or dizziness, dyspnea, severe hypotension (below 90 mm Hg), and (2) a resting ventricular rate below 50 beats/minute.

All patients underwent 24-hour ambulatory ECG studies at hospital discharge and after six to12 months of treatment. During the day of the test, patients were instructed to conduct their activities as usual. The 24-hour average ventricular rates were calculated according to the ambulatory ECG.

We obtained follow-up information by conducting telephone interviews with the patients or with follow-up visits by two physicians (one physician for the controls and another physician for the treated group). Topics included survivorship, the NYHA classification, chronic HF symptoms or signs, hospitalization, and the use of medications. The interviewer was not informed of the immediate outcome, the presence of valvular lesions, echocardiographic data, or the 24-hour ECG at discharge.

Echocardiography

Echocardiographic studies were performed with the HDI 5000 ultrasound system (Philips, The Netherlands). Both groups of patients received Doppler echocardiographic examinations at hospital discharge and after six to 12 months with an acceptable two-dimensional registration. All images were recorded and weresubsequently analyzed by experienced ultrasound physicians who did not know the patients’ classification or treatment.
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LA diameters and LV end-systole and end-diastole dimensions were assessed by apical four-chamber views. The longest RR intervals (pauses between heartbeats) were selected to measure the ejection fraction (EF) as the best function seen for AF. The single-plane ellipse formula was used to calculate the EF. LV function was categorized as definitely impaired if the EF was less than 40%.

Predominant mitral stenosis was defined as (1) being of at least moderate severity, with a mitral valve area smaller than 1.4 cm2; (2) a dilated left atrium and a hypertrophic right ventricle (RV); (3) mild mitral valve regurgitation or mild aortic lesions without a dilated left ventricle or mild mitral valve regurgitation without any other lesions.

Six-Minute Walking Distance

At discharge and after six to 12 months of treatment, walking distances over a period of six minutes were measured for all patients. Instruction on walking exercise was given two or three times before the formal walking distance was determined. After a rest of at least 30 minutes, the average six-minute walking distance, measured in meters, was obtained two or three times.

Statistical Analysis

Measurement data are presented as mean ± standard deviation (SD). To compare baseline values and changes at the end of six to 12 months, we used the paired Student’s t test for continuous variables within groups and the non-paired t test between groups. We used the x2 test to evaluate between-group differences in enumeration data assessment. A P value of less than .05 was considered statistically significant. NYHA classes I, II, III, and IV, respectively, were calculated as scores of 1, 2, 3, and 4.


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