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

In a randomly selected population screening study of 8450 menand 9039 women 33 to 71 years of age conducted in Iceland in1967–1977, 27 men and 17 women were found to have leftbundle branch bock (LBBB). The prevalence of LBBB at that timewas 0.43% for men and 0.28% for women. The incidence of LBBBwas 3.2 per 10 000 per year for men and 3.7 per 10 000 per yearfor women.All except one of 37 alive patients with LBBB wereexamined in 1984 including chest X-ray, echocardiography andexercise testing (Bruce protocol). Eight men had had myocardialinfarction (P<0.05), 12 had angina pectoris, 15 had hypertension,7 had cardiomyopathy, 13 had primary conduction disease, and3 had pacemakers. Five men and two women had died in comparisonwith 18 men and 1 woman in an age-matched control group of 176people (P ns). Three of 5 decreased LBBB men had cardiomyopathyat autopsy. Three men died suddenly. The two women died of noncardiaccauses. Only one patient in the control group had cardiomyopathy(P< 0.01). There was no significant difference in other cardiacdiagnoses between the groups. Eleven LBBB women out of thirteenhad a normal exercise duration (6 min) and 11/17 men exercisednormally (7 min). In comparison with the control group, theLBBB patients had an increased LV diameter 2.85±0.38vs 2.58±0.38 cm m^-2 body surface area (P<0.01). Therewas no difference between the groups in left atrial diameteror LV wall thickness.In conclusion, the prevalence of LBBB was0.43% for men and 0.28% for women of middle age. The incidencewas 3.2 per 10 000 per year for men and 3.7 per 10 000 per yearfor women. The prognosis of LBBB is relatively benign apartfrom its association with dilated cardiomyopathy. Few patientsrequire pacemakers. The mean LV diameter is increased in randomlyselected patients with LBBB, but only those with an underlyingdisorder.     

Ventricular Dysrhythmias in Middle-aged Hypertensive Men Treated Either with a Diuretic Agent Or a β-Blocker

ABSTRACT. The purpose of this study was to identify the frequency of cardiac dysrhythmias in two similar groups of hypertensive middle-aged males (age 45–66). They had previously been randomized either to a diuretic treatment (n=42), or a β-blocking agent (n=41). A 24-hour ambulatory Holter monitoring, and serum potassium, was obtained in all patients, serum magnesium was measured in 35 patients. The mean number of ventricular premature beats (VPBs) and the frequency of complex arrhythmias (19 vs. 5) was significantly higher in the diuretic group (p<0.01). The serum potassium was significantly lower (p<0.001) in the diuretic group, and there was a significant (p<0.005) inverse correlation between the number of VPBs and the serum potassium in all treated patients. The patients with complex arrhythmias were older (p<0.01) than the remainder of the patients. No correlation between serum magnesium and VPBs or complex arrhythmias was found. This study demonstrates increased frequency of VPBs in older hypertensive males, treated with diuretics, and that hypokalaemia predisposes to increased cardiac arrhythmias. We conclude that in older mildly hypertensive men hypokalaemia should be avoided.     

Chronic atrial fibrillation-- epidemiologic features and 14 year follow-up: A case control study

In a randomly selected population of 9067 individuals, 32–64years of age in 1967–1970, 25 (0.28%) had chronic atrialfibrillation (CAF). Eight had lone atrial fibrillation. In 1984the cases were compared with an age- and sex-matched controlgroup of 50 and found to have more cerebrovascular accidents(6 versus 2; P < 0.05), congestive heart failure (9 versus1; P < 0.001), and valvular rheumatic heart disease (3 versus0) or history consistent with rheumatic fever (6 versus 0; P< 0.01). The mortality in the CAF group was 60% higher dueto an excess in cardiovascular (relative risk 6.1; P<0.05)and cerebrovascular (relative risk 12.2; P<0.05) causes.The prevalence or incidence of ischaemic or hypertensive heartdisease or the presence of coronary risk factors did not significantlydiffer in the two groups. By M-mode echocardiography the leftatrial size, left ventricular enddiastolic dimension and leftventricular mass were increased in the CAF patients, while thesystolic left ventricular shortening was significantly less. Thus, the prevalence of CAF is low in a randomly selected population32–64 years of age and CAF is not strongly associatedwith ischaemic heart disease or hypertension. The CAF patientshave an increased risk of dying prematurely particularly fromcerebrovascular causes, even in the absence of valve disease.     

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

In a randomly selected population screening study of 8450 menand 9039 women 33 to 71 years of age conducted in Iceland in1967–1977, 27 men and 17 women were found to have leftbundle branch bock (LBBB). The prevalence of LBBB at that timewas 0.43% for men and 0.28% for women. The incidence of LBBBwas 3.2 per 10 000 per year for men and 3.7 per 10 000 per yearfor women.All except one of 37 alive patients with LBBB wereexamined in 1984 including chest X-ray, echocardiography andexercise testing (Bruce protocol). Eight men had had myocardialinfarction (P<0.05), 12 had angina pectoris, 15 had hypertension,7 had cardiomyopathy, 13 had primary conduction disease, and3 had pacemakers. Five men and two women had died in comparisonwith 18 men and 1 woman in an age-matched control group of 176people (P ns). Three of 5 decreased LBBB men had cardiomyopathyat autopsy. Three men died suddenly. The two women died of noncardiaccauses. Only one patient in the control group had cardiomyopathy(P< 0.01). There was no significant difference in other cardiacdiagnoses between the groups. Eleven LBBB women out of thirteenhad a normal exercise duration (6 min) and 11/17 men exercisednormally (7 min). In comparison with the control group, theLBBB patients had an increased LV diameter 2.85±0.38vs 2.58±0.38 cm m^-2 body surface area (P<0.01). Therewas no difference between the groups in left atrial diameteror LV wall thickness.In conclusion, the prevalence of LBBB was0.43% for men and 0.28% for women of middle age. The incidencewas 3.2 per 10 000 per year for men and 3.7 per 10 000 per yearfor women. The prognosis of LBBB is relatively benign apartfrom its association with dilated cardiomyopathy. Few patientsrequire pacemakers. The mean LV diameter is increased in randomlyselected patients with LBBB, but only those with an underlyingdisorder.     

The epidemiology of right bundle branch block and its association with cardiovascular morbidity -- The Reykjavik Study

This study is based on the Reykjavik Study, a long-term prospectivecardiovascular survey, which included a representative populationof 9135 men and 9627 women, 33–79 years old, who wereinvited to participate during the years 1967–91. Right bundle branch block (RBBB) was found in 126 men and 67women. The prevalence increased with age, from 0% among menand women 30–39 years of age to 4.1% and 1.6% in men andwomen, respectively, who where 75–79 years old. The incidenceincreased with age. In men younger than 60 years RBBB had asignificant relationship with hypertension (P<0.05), elevatedfasting blood glucose (P=0.05), and increased heart size (P<0.05). In men with RBBB regardless of age, an association wasfound with cardiomegaly (P<0.05), ischaemic heart disease(P<005), arrhythmias (P<0.001) and bradycardia (P<0.01).A higher mortality from heart disease (P<0.01) was foundin men with RBBB compared to the control population. This wasnot significant when risk factors of heart disease were takeninto account by multivanate Cox analysis. There was a relationship(P<0.05) between hypertension and RBBB in women younger than60 years. RBBB in women younger than 60 years is often associated withhypertension and in men younger than 60 it is often associatedwith an underlying cardiovascular disease, hypertension, cardiomegalyand elevated blood glucose.     

Arachidonic Acid Level of Non-esterified Fatty Acids and Phospholipids in Serum and Heart Muscle of Patients with Fatal Myocardial Infarction

ABSTRACT The relationship between non-esterified fatty acids (NEFA) in serum and heart muscle was examined in 15 patients who died of myocardial infarction (MI) and seven people who died suddenly in accidents. There was no correlation between NEFA levels of serum and non-infarcted cardiac muscle in patients with fatal MI. No significant difference was encountered in cardiac NEFA content between patients with fatal MI and people who died in accidents. The phospholipid (PL) content was significantly lower in patients with fatal MI than observed in people who died in accidents. The arachidonic acid (20: 4 (n-6)) concentration of serum NEFA was significantly lower in patients with fatal MI compared to normal subjects. The cardiac NEFA and PL in patients with fatal MI contained significantly lower percentage levels of arachidonic acid compared to people who died in accidents. The results indicate that the death of the MI patients was not accompanied by elevated cardiac NEFA levels.     

Additive Effects of Moderate Dietary Salt Reduction and Captopril in Hypertension

ABSTRACT In a randomized, cross-over study 27 patients had diastolic blood pressure of ≥ 96 mmHg during four visits without treatment. Following captopril 25 mg b.i.d. nine patients' blood pressure was ≤ 90 mmHg. The remaining 18 were randomized into two treatment modalities, captopril and moderate dietary salt reduction, and captopril and hydrochlorothiazide 25 mg daily. Following a wash-out period the groups crossed over to the alternative treatment. At the end of the control period the average blood pressure was 151/100 ± 12/6 mmHg recumbent and 140/91 ± 11/7 standing, following captopril 144/94 ± 13/5 and 132/92 ± 12/6, respectively, with low salt diet addded to captopril 140/91 ± 12/6 and 128/89 ± 11/6 and with hydrochlorothiazide and captopril 133/86 ± 12/7 and 120/84 ± 11/7 mmHg supine and erect, respectively. It is concluded that moderate dietary salt reduction, which is easily advised, will significantly potentiate the blood pressure fall following captopril treatment in moderate arterial hypertension.