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Atrial fibrillation in patients with idiopathic hypertrophic subaortic stenosis
Insights
Atrial fibrillation significantly worsens outcomes for patients with idiopathic hypertrophic subaortic stenosis, causing severe deterioration and low cardiac output. Early intervention is crucial for managing this arrhythmia and its complications.
Area of Science:
- Cardiology
- Internal Medicine
Background:
- Idiopathic hypertrophic subaortic stenosis (IHSS) is a significant cardiovascular condition.
- Atrial fibrillation (AF) is a known complication, but its impact on IHSS patients requires further elucidation.
Purpose of the Study:
- To investigate the clinical and hemodynamic consequences of atrial fibrillation in patients with idiopathic hypertrophic subaortic stenosis.
- To assess the impact of AF on cardiac output and patient outcomes.
Main Methods:
- Retrospective analysis of 167 patients with IHSS, focusing on 16 who developed atrial fibrillation.
- Clinical assessment, hemodynamic measurements (cardiac output), and follow-up data collection.
Main Results:
- Atrial fibrillation occurred in 10% of IHSS patients, typically late in the disease course.
- AF onset was associated with severe clinical deterioration, low cardiac output (1.9 L/min/m²), and often recurrence after cardioversion.
- Outcomes included high rates of heart disease-related death (3/16) and cerebral emboli (4/16).
Conclusions:
- Atrial fibrillation precipitates severe clinical decline in IHSS patients due to impaired ventricular filling and irregular rhythm affecting outflow obstruction.
- Management with digitalis showed improvement, but electrical cardioversion often failed long-term.
- AF significantly worsens prognosis in IHSS, highlighting the need for careful monitoring and management.
Abstract:
Atrial fibrillation occurred in 16 (10%) of 167 patients with idiopathic hypertrophic subaortic stenosis. The clinical and haemodynamic findings in these 16 patients are presented. Atrial fibrillation appeared late in the course of the disease, and its occurrence did not seem to be related to the severity of left ventricular outflow obstruction or to the amount of associated mitral regurgitation. In each patient the onset of the arrhythmia was accompanied by severe clinical deterioration, which often necessitated urgent medical treatment. Digitalis was administered to all 16 patients with subsequent clinical improvement in 15. Electrical cardioversion was uniformly successful in restoring sinus rhythm, but atrial fibrillation usually recurred. In each of 8 patients catheterized during atrial fibrillation, cardiac output was strikingly low (average, 1.9 l./min./m.(2)), whereas it was normal in 10 of 13 patients studied in sinus rhythm. The duration of follow-up from the onset of atrial fibrillation has averaged 5 years, and 3 of the 16 patients have died of causes related to their heart disease. Four have suffered cerebral emboli. Only 5 patients are now in stable sinus rhythm; in general, they are less symptomatic than the patients in whom atrial fibrillation has recurred.The unusually severe clinical deterioration at the onset of atrial fibrillation and the low cardiac output measured during catheterization are thought to be related to the loss of the important contribution to ventricular filling of atrial systole in patients with poorly compliant ventricles, and to the effect of an irregular ventricular rhythm on the variable nature of the outflow obstruction.