Chun-Ka Wong

Diagnostic Performance of a Smartphone-Based Photoplethysmographic Application for Atrial Fibrillation Screening in a Primary Care Setting.

Background Diagnosing atrial fibrillation (AF) before ischemic stroke occurs is a priority for stroke prevention in AF. Smartphone camera–based photoplethysmographic (PPG) pulse waveform measurement discriminates between different heart rhythms, but its ability to diagnose AF in real‐world situations has not been adequately investigated. We sought to assess the diagnostic performance of a standalone smartphone PPG application, Cardiio Rhythm, for AF screening in primary care setting. Methods and Results Patients with hypertension, with diabetes mellitus, and/or aged ≥65 years were recruited. A single‐lead ECG was recorded by using the AliveCor heart monitor with tracings reviewed subsequently by 2 cardiologists to provide the reference standard. PPG measurements were performed by using the Cardiio Rhythm smartphone application. AF was diagnosed in 28 (2.76%) of 1013 participants. The diagnostic sensitivity of the Cardiio Rhythm for AF detection was 92.9% (95% CI] 77–99%) and was higher than that of the AliveCor automated algorithm (71.4% [95% CI 51–87%]). The specificities of Cardiio Rhythm and the AliveCor automated algorithm were comparable (97.7% [95% CI: 97–99%] versus 99.4% [95% CI 99–100%]). The positive predictive value of the Cardiio Rhythm was lower than that of the AliveCor automated algorithm (53.1% [95% CI 38–67%] versus 76.9% [95% CI 56–91%]); both had a very high negative predictive value (99.8% [95% CI 99–100%] versus 99.2% [95% CI 98–100%]). Conclusions The Cardiio Rhythm smartphone PPG application provides an accurate and reliable means to detect AF in patients at risk of developing AF and has the potential to enable population‐based screening for AF.

Head-to-Head Comparison of the AliveCor Heart Monitor and Microlife WatchBP Office AFIB for Atrial Fibrillation Screening in a Primary Care Setting

The diagnosis of atrial fibrillation (AF) before stroke is a priority in successful stroke prevention. Despite guidelines that advocate pulse palpation for AF screening, it is not performed routinely in clinical practice. Various handheld or smartphone devices designed to specifically detect AF have gained much popularity. Of these state-of-the-art devices, the AliveCor Heart Monitor, a smartphone-based heart monitor that incorporates dry electrodes mounted on a smartphone case capable of recording a single-lead ECG, has already been US Food and Drug Administration-cleared and Conformite Europeene-marked. In Europe, an automatic oscillometric blood pressure device that incorporates a specific algorithm to detect AF (Microlife WatchBP Office AFIB, Microlife AG) has been recommended by the UK National Institute for Health and Care Excellence to screen for AF during office blood pressure measurement in patients ≥65 years of age. These new devices have typically been evaluated in relatively small populations and not compared head to head. Their general use for widespread AF screening in a primary healthcare setting remains questionable. We report the findings of a prospective AF screening study coordinated by the University of Hong Kong and the Department of …

Prevalence, Predictors and Clinical Outcome of Residual Pulmonary Hypertension Following Tricuspid Annuloplasty.

Background Tricuspid annuloplasty is increasingly performed during left heart valve surgery, but the long‐term clinical outcome postoperatively is not satisfactory. The aim of this study was to determine whether residual pulmonary hypertension (PHT) contributes to the adverse outcome. Methods and Results One‐hundred thirty‐seven patients (age 61±11 years; men, 30%) who underwent tricuspid annuloplasty during left‐side valve surgery were enrolled. The mean pulmonary artery systolic pressure before surgery was 49±13 mm Hg and 32±15 mm Hg following surgery. Patients were divided into 3 groups according to postoperative pulmonary artery systolic pressure: no residual PHT (n=78, 57%), mild residual PHT (n=43, 31%), or significant residual PHT (n=16, 12%). A preoperative larger right ventricular (RV) geometry and tricuspid valve tethering area were associated with mild or significant residual PHT. A total of 24 adverse events (20 heart failures and 4 cardiovascular deaths) occurred during a median follow‐up of 25 months. Kaplan–Meier survival curve demonstrated that patients with significant residual PHT had the highest percentage of adverse events followed by those with mild residual PHT. Patients with no residual PHT had a very low risk of adverse events. Multivariable Cox regression analysis revealed that both mild (hazard ratio=4.94; 95% CI =1.34–18.16; P=0.02) and significant residual PHT (hazard ratio=8.67; 95% CI =2.43–30.98; P<0.01) were independent factors associated with adverse events. Conclusions The present study demonstrated that 43% of patients who underwent tricuspid annuloplasty had residual PHT. The presence of mild or significant residual PHT was associated with adverse events in these patients.

The effects of hyperuricaemia on flow-mediated and nitroglycerin-mediated dilatation in high-risk patients

BACKGROUND AND AIMS Uric acid is emerging as one of the newer risk markers to consider in the cardiovascular risk assessment because it is demonstrated to be associated with adverse cardiovascular outcomes, particularly in high cardiovascular risk patients. One of the proposed mechanisms involving hyperuricaemia is the development of vascular damage. The aim of this study is to examine the role of hyperuricaemia on vascular function in patients with high cardiovascular risk. METHODS AND RESULTS We examined the clinical significance of hyperuricaemia in relation to vasomotor response of the brachial artery by using high-resolution ultrasound in 304 subjects with coronary artery disease and/or diabetes. Nitroglycerin-mediated dilatation (NMD) was significantly lower in the hyperuricaemic group compared with the normouricaemic group (12.8 ± 6.9% vs. 16.2 ± 7.7%, p < 0.001), but no significant difference was observed in flow-mediated dilatation (FMD) between the two groups [3.78 (95% CR: 1.5-9.9) vs. 3.88 (95% CR: -2.6 to 9.9), p = 0.78]. Multivariate analysis demonstrated that smoking was the strongest predictor of FMD (b = -0.81, p = 0.02); and that smoking (b = -2.62, p = 0.003), SBP (b = -0.11, p = 0.001), hyperuricaemia (b = -2.11, p = 0.02) and use of nitrates (b = -3.30, p = 0.001) were independent predictors of NMD. CONCLUSION High cardiovascular risk patients with hyperuricaemia had a lower NMD than those with normouricaemia. Importantly, hyperuricaemia was independently associated with NMD after multivariable adjustments. To further understand the pathophysiological mechanisms involving hyperuricaemia, particularly in the context of impaired NMD, further experimental and clinical studies are needed.

Diagnostic assessment of a deep learning system for detecting atrial fibrillation in pulse waveforms

Objective To evaluate the diagnostic performance of a deep learning system for automated detection of atrial fibrillation (AF) in photoplethysmographic (PPG) pulse waveforms. Methods We trained a deep convolutional neural network (DCNN) to detect AF in 17 s PPG waveforms using a training data set of 149 048 PPG waveforms constructed from several publicly available PPG databases. The DCNN was validated using an independent test data set of 3039 smartphone-acquired PPG waveforms from adults at high risk of AF at a general outpatient clinic against ECG tracings reviewed by two cardiologists. Six established AF detectors based on handcrafted features were evaluated on the same test data set for performance comparison. Results In the validation data set (3039 PPG waveforms) consisting of three sequential PPG waveforms from 1013 participants (mean (SD) age, 68.4 (12.2) years; 46.8% men), the prevalence of AF was 2.8%. The area under the receiver operating characteristic curve (AUC) of the DCNN for AF detection was 0.997 (95% CI 0.996 to 0.999) and was significantly higher than all the other AF detectors (AUC range: 0.924–0.985). The sensitivity of the DCNN was 95.2% (95% CI 88.3% to 98.7%), specificity was 99.0% (95% CI 98.6% to 99.3%), positive predictive value (PPV) was 72.7% (95% CI 65.1% to 79.3%) and negative predictive value (NPV) was 99.9% (95% CI 99.7% to 100%) using a single 17 s PPG waveform. Using the three sequential PPG waveforms in combination (<1 min in total), the sensitivity was 100.0% (95% CI 87.7% to 100%), specificity was 99.6% (95% CI 99.0% to 99.9%), PPV was 87.5% (95% CI 72.5% to 94.9%) and NPV was 100% (95% CI 99.4% to 100%). Conclusions In this evaluation of PPG waveforms from adults screened for AF in a real-world primary care setting, the DCNN had high sensitivity, specificity, PPV and NPV for detecting AF, outperforming other state-of-the-art methods based on handcrafted features.

Impact of provision of time in therapeutic range value on anticoagulation management in atrial fibrillation patients on warfarin

Introduction The importance of time in therapeutic range (TTR) in patients prescribed warfarin therapy for stroke prevention in atrial fibrillation (AF) cannot be overemphasised. Aim To evaluate the impact of provision of TTR results during clinic visits on anticoagulation management. Design Single-centred, randomised controlled study. Setting Fifteen arrhythmia clinics in Hong Kong. Patients AF patients prescribed warfarin. Interventions Provision of TTR or no provision of TTR. Main outcome measures A documented discussion between doctors and patients about switching warfarin to a non-vitamin K oral anticoagulant (NOAC). Results Four hundred and eighty one patients with AF prescribed warfarin were randomly assigned to (1) a TTR provision group or (2) control. Their mean age was 73.6±12.0 years and 60.7% were men. The mean CHA2DS2-VASc score was 3.2±1.6 and the mean HASBLED score was 1.7±1.2. The mean TTR was 63.9%±29.9%. At the index clinic visit, 71 of 481 patients (14.8%) had a documented discussion about switching warfarin to a NOAC. Patients with provision of TTR results were more likely to discuss switching warfarin to a NOAC than controls (19.1% vs 10.6%, P=0.03), especially those with a TTR <65% (35.2% vs 10.6%, P<0.001). A higher proportion of patients with provision of TTR results switched to a NOAC (5.9% vs 4.1%, P=0.49). Conclusions The provision of TTR among patients on warfarin was associated with a discussion about switching from warfarin to a NOAC in those with TTR <65%, but did not result in actual switching to a NOAC, suggesting additional barriers.

Letter by Wong et al Regarding Article, “Pregnancy and the Risk of Aortic Dissection or Rupture: A Cohort-Crossover Analysis”

We congratulate Kamel and colleagues1 on their article in Circulation which demonstrated an elevated risk of aortic dissection or rupture during pregnancy in a large cohort of pregnant women. Out of 6 566 826 pregnancies in 4 933 697 women, 36 aortic complications occurred during pregnancy or the postpartum period, with a reassuringly low absolute risk of 5.5 per million patients. Nonetheless, certain aspects warrant further discussion. As expected, in this study, patients with an underlying connective tissue disease, such as Marfan, Ehler-Danlos, or Turner syndrome, had a 1000-time higher risk of pregnancy-related aortic complications than those without. …