A practical score for risk stratification of embolic stroke in hypertrophic cardiomyopathy

Abstract

Introduction: Embolic stroke (ES) is a major cause of morbidity in hypertrophic cardiomyopathy (HCM), often related to atrial fibrillation (AF). This study assessed predictors of ES in subjects with HCM in a long-term follow study in Brazil.Methods: In a prospective observational study, 172 consecutive HCM subjects (87 males; median 40 y.o.) were enrolled. HCM forms were: 135 septal asymmetric, 19 apical and 17 other. All were followed at scheduled outpatient visits. ECG and echocardiographic data were regularly collected. Medical management was at discretion of attending physician. Primary outcome was ES. Clinical variables included paroxysmal and permanent AF, CHADS2 score and heart failure. Variables assessed on echocardiogram included left atrial diameter (LAD), end diastolic (EDD) and systolic (ESD) midventricular diameters, and left ventricular outflow tract gradient (LVOTG). ROC curves optimized numerical thresholds. Logistic regression model assessed predictors of ES. A risk score was built by weighting independent predictors of ES with respective β coefficients rounded to nearest integer and summing up (α<0.05).Results: In a median follow-up of 12.3 years (2180 subject·year), 40 subjects had AF (incidence: 10‰/year; 16 paroxysmal and 24 permanent), 17 subjects had ES (4‰/year), and 37 subjects died (9‰/year; nine sudden death, four myocardial infarction, 13 end stage heart failure, five ES, six noncardiac causes). Predictors of ES were permanent AF (β=4.5; odds ratio [OR]=90.3; 95% CI[18.0-454] p<0.001), CHADS2>1 (β=2.0; OR=7.7 [2.7-22.3] p<0.001), LAD>4.5cm (β=2.4; OR=11.5 [3.9-34.2] p=0.001), either EDD>5.8cm or ESD>4.0cm (β=2.8; OR=16.3 [4.3-61.8] p<0.001), LVOTG>38mmHg (β=1.7; OR=5.5 [1.8-16.4] p=0.001), and heart failure (β=2.5; OR=12.4 [3.1-49.0] p<0.001). Only CHADS2>1 (β=2.3; OR=9.9 [1.4-67.7] p=0.02), LVOTG>38mmHg (β=2.5; OR=11.6 [1.5-90.0] p=0.02) and permanent AF (β=3.4; OR=29.5 [3.2-266] p=0.003) were independent predictors of ES. Risk score weighted 2 for CHADS2>1, 3 for LVOTG>38mmHg, 3 for permanent AF, and zero otherwise (AUC=0.94; 95% CI[0.89-0.97] p<0.001). The score ranged from zero to 8 and was split into three risk levels for ES: Low [score<3], Intermediate [score 3-5] and High [score>5] (respectively, 2%, 31%, 64% of ES; p trend<0.001). Taking Low level as reference, Intermediate and High were predictors of ES (Intermediate: OR=21 [4-99] p<0.001, High: OR=83 [17-403] p<0.001).Conclusions: In HCM, CHADS2>1, LVOT gradient>38mmHg and permanent AF are independent predictors of embolic stroke. A practical score conveniently assesses the risk of embolic stroke in this setting.