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Natural history of chronic second-degree atrioventricular nodal block
Insights
Chronic second-degree atrioventricular (AV) nodal block is generally benign in patients without heart disease. However, in those with underlying organic heart disease, the prognosis is poor, often linked to the severity of their condition.
Area of Science:
- Cardiology
- Electrophysiology
- Internal Medicine
Background:
- Chronic second-degree atrioventricular (AV) nodal block, specifically proximal to His (H), is a condition affecting cardiac rhythm.
- Understanding the prognosis and management of this block is crucial for patient outcomes.
Purpose of the Study:
- To evaluate the clinical course and outcomes of patients with documented chronic second-degree AV nodal block.
- To compare prognosis between patients with and without underlying organic heart disease.
Main Methods:
- Retrospective analysis of 56 patients with chronic second-degree AV nodal block (Type I or 2:1 block).
- Prospective follow-up assessing symptoms, need for pacing, and mortality.
- Stratification of patients based on the presence or absence of organic heart disease.
Main Results:
- In patients without organic heart disease (n=19), the course was generally benign, with one requiring pacing for bradyarrhythmic symptoms.
- In patients with organic heart disease (n=37), prognosis was poor, with 10 requiring pacemakers and 16 deaths (including sudden cardiac death and congestive heart failure).
- Outcomes were strongly correlated with the severity of the underlying organic heart disease.
Conclusions:
- Chronic second-degree AV nodal block without organic heart disease typically follows a benign clinical course.
- The presence of organic heart disease significantly worsens the prognosis for patients with chronic second-degree AV nodal block.
- Management strategies should consider the underlying cardiac status to guide treatment and predict outcomes.
Abstract:
This report details our experience with documented chronic second-degree atrioventricular (AV) nodal block (proximal to His [H]) in 56 patients. Forty-six men (82%) and 10 women (18%), ages 18-87 years, were studied. Nineteen of the patients (34%) had no organic heart disease (including seven trained athletes) and 37 (66%) had organic heart disease. ECGs in all patients demonstrated episodes of type I second-degree block; five patients also had periods of 2:1 block. Prospective follow-up patients with no organic heart disease (157-2280 days, mean 1395 +/- 636 days) revealed one patient with clear indication for permanent pacing because of bradyarrhythmic symptoms (permanently placed on day 220 of follow-up). Two patients died nonsuddenly. In patients with organic heart disease (prospective follow-up of 60-2950 days, mean 1347 +/- 825 days), pacemakers were implanted in 10 patients, primarily for treatment of congestive heart failure in eight and syncope in two. Sixteen patients died -- three suddenly, seven with congestive heart failure, two of an acute myocardial infarction and four of causes unrelated to cardiac disease. In summary, chronic second-degree AV nodal block has a relatively benign course in patients without organic heart disease. In patients with organic heart disease, prognosis is poor and related to the severity of underlying heart disease.