Boon-Hor Chong

Queen Mary Hospital, Hong Kong, Hong Kong

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Publications (5)16.4 Total impact

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    ABSTRACT: Background Early identification of individuals who are at risk of developing atrial fibrillation (AF) and ischemic stroke may enable a closer surveillance and thus prompt initiation of oral anticoagulation for stroke prevention. Objective This study sought to investigate whether congestive heart failure, hypertension, age ≥ 75 years, diabetes, previous stroke (CHADS2) and CHA2DS2–vascular disease, age 65–74 years, sex category (CHA2DS2–VASc) scores can predict new-onset AF and/or ischemic stroke in patients presenting with arrhythmic symptoms. Methods and results We prospectively followed up 528 patients (68.5 ± 10.6 years, male 46.2 %) presented for assessment of arrhythmic symptoms but without any documented arrhythmia, including AF for development of new-onset AF and/or ischemic stroke. Their mean CHADS2 and CHA2DS2–VASc scores on presentation were 1.3 ± 1.3 and 2.3 ± 1.5, respectively. After 6.1 years, 89 patients (16.8 %, 2.77 per 100 patient-years) had documented AF, and 65 patients (12.3 %, 2.0 per 100 patient-years) suffered stroke. Both the CHADS2 (C statistic 0.63, 95 % confidence interval (CI) 0.58–0.67, P < 0.0001, optimal cutoff at 1) and CHA2DS2–VASc (C statistic 0.63, 95 % CI 0.59–0.67, P < 0.0001, optimal cutoff at 2) scores provided similar prediction for the new-onset AF. Similarly, CHADS2 (C statistic 0.69, 95 % CI 0.65–0.73, P < 0.0001, optimal cutoff at 2) and CHA2DS2–VASc (C statistic 0.69, 95 % CI 0.65–0.73, P < 0.0001, optimal cutoff at 2) have compatible efficacy for stroke prediction in this Chinese population. Conclusion The CHADS2 and CHA2DS2–VASc scores can be used in patients who presented with arrhythmic symptoms to identify those who are at risk with developing new-onset clinical AF and ischemic stroke for close clinical surveillance and early intervention.
    No preview · Article · Jun 2013 · Journal of Interventional Cardiac Electrophysiology
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    ABSTRACT: Cerebellar hemorrhage is the least common type of intracranial hemorrhage (ICH) encountered in clinical practice, and clinical data concerning the long-term outcomes are limited. This study aimed to investigate the long-term outcomes following spontaneous cerebellar hemorrhage in a cohort of Chinese patients. This single-center observational study was carried out between 1996 and 2010 and included 72 consecutive Chinese patients with a first spontaneous cerebellar hemorrhage. Of 440 patients with primary ICH, 72 (16.4%) had primary cerebellar hemorrhage. The mean age was 67.5 ± 12.3 years and patients were predominantly male (54%). The 30-day mortality was 16.7% with Glasgow coma scale ≤8 as the only predictor. At 6 months, 56.7% of patients who survived the first 30 days had a persistently poor functional status with modified Rankin scale score >2. After a mean follow-up of 4.7 years, 3.3% of patients had recurrent ICH, a recurrence rate of 7.3 per 1,000 patient-years. Ischemic stroke occurred in 12% of patients, an incidence of 25.5 per 1,000 patient-years. This study provided data on the long-term outcome of post-cerebellar hemorrhage in Chinese patients.
    No preview · Article · Mar 2012 · The Cerebellum
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    ABSTRACT: Intracranial haemorrhage (ICH) accounts for ~35% of all strokes in Chinese. Anti-platelet agent is often avoided after an index event due to the possibility of recurrent ICH. This single-centered observational study included 440 consecutive Chinese patients with a first spontaneous ICH surviving the first month performed during 1996-2010. The subjects were identified, and their clinical characteristics, anti-platelet therapy after ICH, and outcomes including recurrent ICH, ischaemic stroke, and acute coronary syndrome were checked from hospital records. Of these 440 patients, 56 patients (12.7%) were prescribed aspirin (312 patient-aspirin years). After a follow-up of 62.2 ± 1.8 months, 47 patients had recurrent ICH (10.7%, 20.6 per 1,000 patient years). Patients prescribed aspirin did not have a higher risk of recurrent ICH compared with those not prescribed aspirin (22.7 per 1,000 patient-aspirin years vs. 22.4 per 1,000 patient years, p=0.70). Multivariate analysis identified age > 60 years (hazard ratio [HR]: 2.0, 95% confidence interval [CI]: 1.07-3.85, p=0.03) and hypertension (HR: 2.0, 95% CI: 1.06-3.75, p=0.03) as independent predictors for recurrent ICH. In a subgroup analysis including 127 patients with standard indications for aspirin of whom 56 were prescribed aspirin, the incidence of combined vascular events including recurrent ICH, ischaemic stroke, and acute coronary syndrome was statistically lower in patients prescribed aspirin than those not prescribed aspirin (52.4 per 1,000 patient-aspirin years, vs. 112.8 per 1,000 patient-years, p=0.04). In conclusion, we observed in a cohort of Chinese post-ICH patients that aspirin use was not associated with an increased risk for a recurrent ICH.
    No preview · Article · Dec 2011 · Thrombosis and Haemostasis
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    ABSTRACT: To investigate the relation between baseline frequency of premature atrial complexes (PACs) and new atrial fibrillation (AF) and adverse cardiovascular events. Four hundred and twenty-eight patients without AF or structural heart disease undergoing 24 h electrocardiography monitoring for palpitations, dizziness, or syncope were recruited. One hundred and seven patients with number of PACs at the top quartile (i.e. > 100PACs/day) were defined to have frequent PACs. After 6.1-year follow-up, 31 patients (29%) with frequent PACs developed AF compared with 29 patients (9%) with PACs ≤ 100/day (P< 0.01). Cox regression analysis revealed that frequent PACs [hazard ratio (HR): 3.22 (95% confidence interval (CI): 1.9-5.5; P< 0.001)], age >75 years (HR: 2.3; 95% CI: 1.3-3.9; P= 0.004), and coronary artery disease (HR: 2.5; 95% CI: 1.4-4.4; P= 0.002) were independent predictors for new AF. Concerning the composite endpoint (ischaemic stroke, heart failure, and death), patients with frequent PACs were more at risk than those without (34.5 vs. 19.3%) (HR: 1.95; 95% CI: 1.37-3.50; P= 0.001). Cox regression analysis showed that age >75 years (HR: 2.2; 95% CI: 1.47-3.41; P< 0.001), coronary artery disease (HR: 2.2, 95% CI: 1.42-3.44, P< 0.001), and frequent PACs (HR: 1.6; 95% CI: 1.04-2.44; P= 0.03) were independent predictors for the secondary composite endpoint. Frequent PACs predict new AF and adverse cardiovascular events.
    No preview · Article · Dec 2011 · Europace
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    ABSTRACT: Heart failure occurs in 6% of hyperthyroid patients. Nonetheless, only half of those with hyperthyroidism-related heart failure have impaired left ventricular (LV) systolic function. Thus, diastolic dysfunction may play an important role in the pathogenesis. We performed serial echocardiographic examinations in 70 consecutive patients with hyperthyroidism (39 ± 2 years, 47 women) to determine their diastolic function and repeated the examinations 6 months after achieving a euthyroid state. All patients had normal LV systolic function, but diastolic dysfunction was detected in 22 cases (mild: 3, moderate: 15 and severe: 4). The prevalence of diastolic dysfunction increased with age from 17·9 % in patients <40 years to 100% in those >60 years. Increasing age was the only independent predictor for diastolic dysfunction in hyperthyroid patients. After achievement of a euthyroid state, most patients (16/22, 72%) had completely normalized diastolic function: 100% of patients <40 years, 33·3 % of those ≥ 60 years. Further analyses revealed significant age-related differences in the cardiovascular response to hyperthyroidism. Among patients <40 years, hyperthyroidism resulted in a marked reduction in total peripheral vascular resistance, increased cardiac output and enhanced diastolic function as determined by E'. No such significant change in total peripheral vascular resistance or cardiac output was observed in hyperthyroid patients ≥ 40 years. In addition, hyperthyroidism was associated with reduced E', signifying diastolic dysfunction in older hyperthyroid patients. Hyperthyroidism is associated with diastolic dysfunction, particularly in older patients. It is partly reversible following achievement of a euthyroid state.
    No preview · Article · May 2011 · Clinical Endocrinology