Atrial septal defect in adults ≥40 years old: negative impact of low arterial oxygen saturation

Background: Although good prognosis and clinical long-term outcome have been commonly reported in minimally symptomatic adult patients with ASD, this information has been based on studies with a relatively small number of adult patients. We studied unoperated patients aged over 40 years to define the patterns of presentation, anatomical characteristics, outcome and predictive factors for free-event survival of major cardiovascular and pulmonary events. Methods and results: Two-hundred survivors of atrial septal defect aged over 40-yr attended from 1985 to 1998 were reviewed and followed-up from 1.6 to 22 years. Patients were classified in three groups according to age at entry: Group 1, between 40 and 49; Group 2; 50 and 59; and Group 3, ≥60 years old. The mean age at presentation was 48.8±9.2 years, and the most common clinical presentations were arrhythmia and dyspnea (51.4%). There were 37 (18.5%) events: 7 heart failure-related, 5 sudden death, 13 severe pulmonary infections, 5 embolisms, and 4 strokes. According to Cox’s regression analysis, predictors of primary end point included age group at presentation (hazard ratio 1.71, 95% confidence limits 1.16 to 2.54), and either pulmonary hypertension (mean pulmonary pressure >35 mmHg; hazard RATIO=0.65 (4.6, confidence limits 2.2 to 9.5) or, arterial oxygen saturation <80% (hazard ratio 1.71, 95% confidence limits 1.16 to 2.54). Conclusions: This study supports that long term outcome of patients aged >40 years with unoperated ASD is importantly determined by the mPAP (>35 mmHg), SaO2% (_80) and the age at diagnosis. Nevertheless we identified an inverse association between the mPAP level and SaO2% (interaction). The event-free survival expectancy may be estimated using the age at diagnosis and either SaO2% or mPAP. This prognostic stratification based on pathophysiological principles, may help in making decisions for therapeutic interventions. SaO2% should always be measured as a part of the initial clinical approach of those patients with atrial septal defect aged over 40 years.