Structural heart disease as the cause of syncope

We described the clinical evolution of patients with structural heart disease presenting at the emergency room with syncope. Patients were stratified according to their syncope etiology and available scores for syncope prognostication. Cox proportional hazard models were used to investigate the relationship between etiology of the syncope and event-free survival. Of the 82,678 emergency visits during the study period, 160 (0.16%) patients were there due to syncope, having a previous diagnosis of structural heart disease. During the median follow-up of 33.8±13.8 months, mean age at the qualifying syncope event was 68.3 years and 40.6% of patients were male. Syncope was vasovagal in 32%, cardiogenic in 57%, orthostatic hypotension in 6%, and of unknown causes in 5% of patients. The primary composite endpoint death, readmission, and emergency visit in 30 days was 39.4% in vasovagal syncope and 60.6% cardiogenic syncope (P<0.001). Primary endpoint-free survival was lower for patients with cardiogenic syncope (HR=2.97, 95%CI=1.94-4.55; P<0.001). The scores were analyzed for diagnostic performance with area under the curve (AUC) and did not help differentiate patients with an increased risk of adverse events. The differential diagnosis of syncope causes in patients with structural heart disease is important, because vasovagal and postural hypotension have better survival and less probability of emergency room or hospital readmission. The available scores are not reliable tools for prognosis in this specific patient population.

本研究描述了因晕厥（syncope）就诊于急诊（emergency room）的结构性心脏病（structural heart disease）患者的临床转归。研究人员根据患者的晕厥病因（etiology）及可用的晕厥预后评分系统对其进行分层。采用Cox比例风险模型（Cox proportional hazard models）探究晕厥病因与无事件生存期（event-free survival）之间的关联。研究期间共计82678例急诊就诊病例，其中160例（占比0.16%）患者因晕厥就诊，且既往确诊结构性心脏病。中位随访时长为33.8±13.8个月，本次纳入研究的晕厥发作时患者的平均年龄为68.3岁，其中男性占比40.6%。患者中，32%为血管迷走性晕厥（vasovagal syncope），57%为心源性晕厥（cardiogenic syncope），6%为体位性低血压（orthostatic hypotension）相关性晕厥，另有5%病因不明。以30天内死亡、再入院及急诊就诊为主要复合终点（composite endpoint），血管迷走性晕厥患者的复合终点发生率为39.4%，心源性晕厥患者则为60.6%（P<0.001）。心源性晕厥患者的无主要终点生存率更低（风险比HR=2.97，95%置信区间95%CI=1.94-4.55；P<0.001）。采用曲线下面积（AUC, area under the curve）分析各评分系统的诊断效能，结果显示其无法有效区分不良事件风险升高的患者。对于结构性心脏病患者而言，明确晕厥病因的鉴别诊断至关重要，因为血管迷走性晕厥与体位性低血压相关性晕厥患者的生存率更高，急诊就诊及住院再入院的概率更低。现有评分系统并不适用于该特定患者群体的预后评估。