Related Experiment Videos
Significance of left axis deviation in patients with chronic left bundle branch block
Insights
Patients with left bundle branch block and left axis deviation show increased risks of heart disease, conduction problems, and higher cardiovascular mortality compared to those with a normal axis.
Area of Science:
- Cardiology
- Electrophysiology
Background:
- Left bundle branch block (LBBB) is a common cardiac condition.
- Axis deviation in LBBB can indicate underlying pathology.
Purpose of the Study:
- To compare clinical characteristics and outcomes of LBBB patients with normal axis versus left axis deviation.
- To investigate the prognostic significance of left axis deviation in LBBB.
Main Methods:
- Retrospective comparison of 49 LBBB patients with normal axis and 53 with left axis deviation.
- Analysis of clinical variables, electrocardiographic intervals, and long-term follow-up data.
- Assessment of atrioventricular (A-V) block development and cardiovascular mortality.
Main Results:
- Left axis deviation was associated with older age, exertional angina, heart failure, cardiomegaly, and coronary artery disease.
- Patients with left axis deviation exhibited prolonged P-R, A-H, H-V intervals, and refractory periods.
- Higher incidence of A-V block and increased cardiovascular mortality were observed in the left axis deviation group.
Conclusions:
- Left axis deviation in LBBB signifies greater myocardial dysfunction and advanced conduction disease.
- Left axis deviation is a marker for poorer prognosis and increased cardiovascular mortality in LBBB patients.
Abstract:
Forty-nine patients with chronic left bundle branch block and a normal frontal axis were compared with 53 patients with left bundle branch block and left axis deviation. The following clinical variables were more frequent (P less than 0.05) in patients with left axis deviation: greater age, exertional angina, congestive heart failure, cardiomegaly, cardiac functional class II to IV, coronary artery disease and presence of organic heart disease. Absence of organic heart disease (primary conduction disease) was seen only in patients with a normal axis. Patients with left axis deviation had longer (P less than 0.05) mean P-R, A-H and H-V intervals and atrial and atrioventricular (A-V) nodal effective refractory periods. All patients were prospectifely followed up for 30 to 2,271 days with a mean +/- standard error of the mean follo-up period of 538 +/- 72 for the group with a normal axis and 604 +/- 72 days for the group with left axis deviation (difference not significant). A-V block developed in three patients (6 percent) with left axis deviation and in none of those with a normal axis. The cumulative 4 year mortality rate for the entire group approached 75 percent. The patients with left axis deviation had greater cardiovascular mortality (P less than 0.05). In conclusion, among patients with left bundle branch block, those with left axis deviation have a greater incidence of myocardial dysfunction, more advanced conduction desease and greater cardiovascular mortality than those with a normal axis.