Impact Of Left Atrial Volume Index On Syncope In Patients With Hypertrophic Cardiomyopathy

Abstract

Introduction Syncope commonly occurs in hypertrophic cardiomyopathy patients (HCM), usually without warning or prodrome and is associated with high risk for sudden death. Moreover, the exact mechanism of syncope cannot be identified making it difficult to predict which patients are at greatest risk for syncope. Prior studies have shown left atrial size to be associated with sudden death with markers of left atrial (LA) remodeling seen in advanced stages of HCM. However, it is unclear if LA structural changes correlate with incidence of syncope. Our aim was to evaluate if there is a correlation between left atrial volume index (LAVI) and occurrence of syncope in HCM patients. Methods This was a retrospective study of 123 HCM patients identified at our institution from 2016-2019. Diagnosis of syncope was identified by chart review. Left atrial volume index was determined by tracing the LA endocardial border in both the apical and four and two chamber view by two-dimensional echocardiography. HCM subtypes were defined as obstructive (presence of systolic anterior motion of the mitral valve—SAM), and non-obstructive (apical variant). Results Of 123 patients, 29 (23.6%) had syncope: 25 of the 100 SAM subjects and 4 of the 23 non-obstructive subjects. No difference in age, gender, or BMI was found between those with syncope and without syncope. LAVI showed a correlation with syncope in HCM patients (p< 0.05). In patients with a diagnosis of syncope, mean LAVI was larger compared to those without history of syncope (43.8±12.6 mL/m2 vs. 37.7±14.3 mL/m2). Each 1 mL/m2 increase in LAVI corresponded to a 1.03 OR risk for syncope. ROC analysis showed a LAVI threshold of 31.8mL/m2 for predicting syncope in all HCM (sensitivity 89.7%, specificity 40.4%) (Figure 1). Conclusion Syncope showed a strong correlation in those with larger LAVI with incremental risk of syncope for each 1 mL/m2 added to LAVI size. Our findings suggest LAVI may have utility as a marker to stratify HCM patients at risk for syncope. Further studies in HCM patients are needed to assess the impact of changes in LAVI size over time on cardiovascular outcomes. Syncope commonly occurs in hypertrophic cardiomyopathy patients (HCM), usually without warning or prodrome and is associated with high risk for sudden death. Moreover, the exact mechanism of syncope cannot be identified making it difficult to predict which patients are at greatest risk for syncope. Prior studies have shown left atrial size to be associated with sudden death with markers of left atrial (LA) remodeling seen in advanced stages of HCM. However, it is unclear if LA structural changes correlate with incidence of syncope. Our aim was to evaluate if there is a correlation between left atrial volume index (LAVI) and occurrence of syncope in HCM patients. This was a retrospective study of 123 HCM patients identified at our institution from 2016-2019. Diagnosis of syncope was identified by chart review. Left atrial volume index was determined by tracing the LA endocardial border in both the apical and four and two chamber view by two-dimensional echocardiography. HCM subtypes were defined as obstructive (presence of systolic anterior motion of the mitral valve—SAM), and non-obstructive (apical variant). Of 123 patients, 29 (23.6%) had syncope: 25 of the 100 SAM subjects and 4 of the 23 non-obstructive subjects. No difference in age, gender, or BMI was found between those with syncope and without syncope. LAVI showed a correlation with syncope in HCM patients (p< 0.05). In patients with a diagnosis of syncope, mean LAVI was larger compared to those without history of syncope (43.8±12.6 mL/m2 vs. 37.7±14.3 mL/m2). Each 1 mL/m2 increase in LAVI corresponded to a 1.03 OR risk for syncope. ROC analysis showed a LAVI threshold of 31.8mL/m2 for predicting syncope in all HCM (sensitivity 89.7%, specificity 40.4%) (Figure 1). Syncope showed a strong correlation in those with larger LAVI with incremental risk of syncope for each 1 mL/m2 added to LAVI size. Our findings suggest LAVI may have utility as a marker to stratify HCM patients at risk for syncope. Further studies in HCM patients are needed to assess the impact of changes in LAVI size over time on cardiovascular outcomes.