Left bundle branch block: prevalence, incidence, follow-up and outcome

Abstract

In a randomly selected population screening study of 8450 men and 9039 women 33 to 71 years of age conducted in Iceland in 1967-1977, 27 men and 17 women were found to have left bundle branch bock (LBBB). The prevalence of LBBB at that time was 0.43% for men and 0.28% for women. The incidence of LBBB was 3.2 per 10,000 per year for men and 3.7 per 10,000 per year for women. All except one of 37 alive patients with LBBB were examined in 1984 including chest X-ray, echocardiography and exercise testing (Bruce protocol). Eight men had had myocardial infarction (P less than 0.05), 12 had angina pectoris, 15 had hypertension, 7 had cardiomyopathy, 13 had primary conduction disease, and 3 had pacemakers. Five men and two women had died in comparison with 18 men and 1 woman in an age-matched control group of 176 people (P : ns). Three of 5 decreased LBBB men had cardiomyopathy at autopsy. Three men died suddenly. The two women died of noncardiac causes. Only one patient in the control group had cardiomyopathy (P less than 0.01). There was no significant difference in other cardiac diagnoses between the groups. Eleven LBBB women out of thirteen had a normal exercise duration (greater than or equal to 6 min) and 11/17 men exercised normally (less than or equal to 7 min). In comparison with the control group, the LBBB patients had an increased LV diameter 2.85 +/- 0.38 vs 2.58 +/- 0.38 cm m-2 body surface area (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Cardiac Resynchronization Therapy on Left Atrial Reverse Remodeling and Spontaneous Echo Contrast

“…Conduction delay leads to abnormal ventricular depolarization and disturbance of the synchrony between interand intraventricular contraction and relaxation (Hardarson et al 1987;Grines et al 1989;Xiao et al 1992;Fahy et al 1996;Nelson et al 2000;Saxon et al 2000). Disturbance of ventricular synchrony causes a shortening in diastolic filling and effective ejection time, reduces stroke volume, prolongs mitral regurgitation and leads to an increase in global and regional wall stress (Grines et al 1989;Xiao et al 1992;Nelson et al 2000).…”

Bundle-Branch Block in a General Male Population

“…13 In the Reykjavik studies, no increased death rate due to coronary artery disease or hypertension was observed among people with left bundle-branch block. 14 In people Ͻ60 years old with right bundle-branch block, there was a positive correlation to hypertension. 15 Several studies have found increased mortality in patients with bundle-branch block and concomitant cardiovascular disease.…”

Cardiac and neuromuscular implications of left bundle branch block in left ventricular hypertrabeculation/noncompaction

“…The relationship of LBB with dilated left ventricle and systolic dysfunction may be explained by impaired myocardial conduction. The occurrence of LBB was associated with increasing left ventricular dimensions and decreasing left ventricular fractional shortening in epidemiological studies (11,12).…”