Pak-Hei Chan

Kissing balloon or sequential dilation of the side branch and main vessel for provisional stenting of bifurcations: lessons from micro-computed tomography and computational simulations

OBJECTIVES This study sought to evaluate post-dilation strategies in bifurcation stenting. BACKGROUND In bifurcation stenting practice, it is still controversial how post-dilation should be performed and whether the kissing balloon (KB) technique is mandatory when only the main vessel (MV) receives a stent. METHODS A series of drug-eluting stents (DES) (n = 26) were deployed in a coronary bifurcation model following a provisional approach. After the deployment of the stent in the MV, post-dilation with the KB technique was compared with a 2-step, sequential post-dilation of the side branch (SB) and MV without kissing. RESULTS The percentage of the SB lumen area free of stent struts was similar after KB (79.1 ± 8.7%) and after the 2-step sequence (74.4 ± 11.6%, p = 0.25), a considerable improvement compared with MV stenting only without dilation of the stent at the SB ostium (30.8 ± 7.8%, p < 0.0001). The rate of strut malapposition in the ostium was 21.3 ± 9.2% after KB and 24.9 ± 10.4% after the 2-step sequence, respectively, a significant reduction compared with a simple SB dilation (55.3 ± 16.8%, p < 0.0001) or MV stenting only (47.0 ± 8.5%, p < 0.0005). KB created a significant elliptical overexpansion of the MV lumen, inducing higher stress concentration proximal to the SB. KB also led to a higher risk of incomplete stent apposition at the proximal stent edge (30.7 ± 26.4% vs. 2.8 ± 9.6% for 2-step, p = 0.0016). CONCLUSIONS Sequential 2-step post-dilation of the SB and MV may offer a simpler and more efficient alternative to final KB technique for provisional stenting of bifurcations.

Ischemic Stroke and Intracranial Hemorrhage With Aspirin, Dabigatran, and Warfarin Impact of Quality of Anticoagulation Control

Background and Purpose— Little is known about the impact of quality of anticoagulation control, as reflected by time in therapeutic range (TTR), on the effectiveness and safety of warfarin therapy in Chinese patients with atrial fibrillation. We investigated the risks of ischemic stroke and intracranial hemorrhage (ICH) in relation to warfarin at various TTRs in a real-world cohort of Chinese patients with atrial fibrillation receiving warfarin and compared with those on dabigatran, aspirin, and no therapy. Methods— This is an observational study. Results— Of 8754 Chinese patients with atrial fibrillation and CHA2DS2-VASc ≥1 (79.5±9.2 years; CHA2DS2-VASc, 4.1±1.5; and Hypertension, Abnormal Renal/Liver Function, Stroke, Bleeding History or Predisposition, Labile International Normalized Ratio, Elderly (>65 years), Drugs/Alcohol Concomitantly [HAS-BLED], 2.2±0.9), 16.3% received warfarin, 41.1% aspirin, 4.5% dabigatran, and 38.1% received no therapy. The incidence of ischemic stroke was highest in patients with no therapy (10.38%/y), followed by patients on aspirin (7.95%/y). The incidence of stroke decreased progressively with increasing TTR quartiles (<17.9%, 17.9%–38.8%, 38.8%–56.2%, and >56.2%) from 7.34%/y (first quartile) to 3.10%/y (fourth quartile). Patients on dabigatran had the lowest incidence of stroke among all groups (2.24%/y). The incidence of ICH was lowest in patients on dabigatran (0.32%/y) compared with those on warfarin (0.90%/y), aspirin (0.80%/y), and no therapy (0.53%/y). ICH incidence decreased with increasing TTR from 1.37%/y (first quartile) to 0.74%/y (fourth quartile). Conclusions— In Chinese patients with atrial fibrillation, the benefits of warfarin therapy for stroke prevention and ICH risk are closely dependent on the quality of anticoagulation, as reflected by TTR. Even at the top TTR quartile, warfarin was associated with a higher stroke and ICH risk than dabigatran.

Optical coherence tomography for guidance of distal cell recrossing in bifurcation stenting: choosing the right cell matters

AIMS The aim of this study was to assess the ability of optical coherence tomography (OCT) to guide recrossing during percutaneous coronary interventions in bifurcations and to reduce strut malapposition. METHODS AND RESULTS Fifty-two patients undergoing elective treatment of bifurcation lesions using provisional stenting as default strategy were included in the study. Patients were divided into two groups: OCT-guided stent recrossing (group 1, n=12), and angiography-guided recrossing (group 2, n=40). Malapposition in the various bifurcation segments was compared in the two groups, using propensity score analysis to correct for confounders. In 4/12 patients (33%) of the OCT-guided group after the first attempt to recross the stent towards the SB the wire was found to have crossed in a proximal cell, requiring a second and in one case a third attempt to successfully cross through a distal cell. Patients who were treated using OCT-guided recrossing had a significantly lower number of malapposed stent struts, especially in the quadrants towards the SB ostium (9.5%[7.5-17.4%] vs 42.3%[31.2-54.7%] in the angiography-guided group, p<0.0001). CONCLUSIONS The rate of strut malapposition was significantly reduced when OCT was used to confirm that wire recrossing was performed in a distal cell of the SB ostium.

Optical coherence tomography: from research to practice

Optical coherence tomography (OCT) is a high-resolution imaging technique with great versatility of applications. In cardiology, OCT has remained hitherto as a research tool for characterization of vulnerable plaques and evaluation of neointimal healing after stenting. However, OCT is now successfully applied in different clinical scenarios, and the introduction of frequency domain analysis simplified its application to the point it can be considered a potential alternative to intravascular ultrasound for clinical decision-making in some cases. This article reviews the use of OCT for assessment of lesion severity, characterization of acute coronary syndromes, guidance of intracoronary stenting, and evaluation of long-term results.

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.

Frequency domain optical coherence tomography for guidance of coronary stenting

OBJECTIVE To evaluate the role of Frequency domain optical coherence tomography (FD-OCT) in guiding stent implantation procedures. METHODS Dragonfly-imaging catheter was used pre-intervention, after pre-dilatation or at various stages of stent deployment/post-dilatation to assess lesion severity, characteristics and guide stent expansion/apposition. RESULTS We performed 398 OCT pull-backs in 108 consecutive patients. The 371 pull-backs analysable, had an average length of 35 mm and encompassed 193 lesions (1.8 lesions per patient). Seventy-six percent of patient had AHA-ACC-class B-C lesions. In the pre-intervention group deferral of treatment was decided for 13/68 pullbacks (19.1%), whereas strategies different from conventional predilatation (e.g. thrombectomy, rotablator, cutting-balloon) were decided in 23 cases (33.8%). After full lesion dilatation 96 pullbacks (25.9%, pre-stenting group) were performed, 46 (47.9%) of which suggested proceeding directly with stenting while 50 (52.1%) suggesting further treatment. Out of the 207 pullbacks in post-stenting group, 29 (14%) suggested new stent implantation because of dissection or residual stenosis; 64 (30.9%) suggested further optimization with high pressure/larger-sized balloon. Average number of pull-backs per patient was 3.4 requiring 75.8 ± 19.3 ml of iopamidol. No major complications were observed. Five cases (4.6%) of contrast-induced nephropathy were reported. CONCLUSIONS Repeated examinations with FD-OCT can be safely used to guide stent selection and improve stent expansion and apposition.

Immediate Results of Bifurcational Stenting Assessed With Optical Coherence Tomography

Background: A tubular stent may adapt with difficulty to coronary bifurcation lesions (CBLs). Methods: Time domain or frequency domain (FD) optical coherence tomography (OCT) was performed to assess strut apposition immediately after stent implantation across four segments inside the bifurcation, in a consecutive series of patients. OCT pullbacks were performed in the main vessel (MV). Results: A total of 13,142 struts in 45 CBL in 41 patients were assessed. Strut malapposition was significantly more frequent in the half bifurcation facing the side‐branch (SB) ostium (42.9%) than in the proximal segment of the bifurcation 11.8%, half bifurcation opposite the SB 6.7%, or the distal segment 5.7% (all P < 0.0001). Lesions (n = 15) treated with stenting of both MV and SB had a total higher rate of malapposition than those (n = 30) treated with stenting of the MV only (17.6% vs. 9.5%; P = 0.0014). In latter group, lesions treated with FD‐OCT‐guided stent implantation (n = 13) presented a lower rate of malapposition than those treated with conventional angiographic‐guided stent implantation (n = 17) (7.1% vs. 17.5%; P = 0.005). Conclusions: In CBL, strut malapposition is particularly high at the SB ostium. However, a strategy of stenting MV only with adjunctive FD‐OCT guidance is associated with lower rates of malapposition.

Continuation of dabigatran therapy in "real-world" practice in Hong Kong

Background Dabigatran, an oral direct thrombin inhibitor, possesses several advantages over warfarin that can in principle simplify the management of stroke prevention in atrial fibrillation (AF). Nonetheless it remains unclear whether these advantages can translate to clinical practice and encourage long-term therapy. The objective was to describe long-term dabigatran therapy for stroke prevention in AF and to identify risk factors for discontinuation of therapy. Methods and Results We studied 467 consecutive Chinese patients (72±11 years, male: 53.8%) with a mean CHA2DS2-VASc score of 3.6 prescribed dabigatran for stroke prevention in AF from March 2010 to September 2013. Over a mean follow-up of 16 months, 101 patients (21.6%) permanently discontinued dabigatran. The mean time-to-discontinuation was 8 months. The most common reason for discontinuation was dyspepsia (30.7%), followed by other adverse events (17.8%) such as minor bleeding (8.9%), major gastrointestinal bleeding (7.9%), and intracranial hemorrhage (1%). Other reasons included dosing frequency (5.9%), fear of side effects (4.0%), lack of laboratory monitoring (1.0%), and cost (1.0%). Multivariable analysis revealed that low baseline estimated glomerular filtration rate (p = 0.02), absence of hypertension (p = 0.01), and prior use of a proton-pump inhibitor (p = 0.02) and H2-receptor blocker (p = 0.01) were independent predictors of drug discontinuation. In addition, there were altogether 9 ischemic strokes (1.5%/years), 3 intracranial hemorrhages (0.5%/year), and 24 major gastrointestinal bleedings (4.1%/year). Conclusion Dabigatran discontinuation is very common amongst Chinese AF patients. This reveals a management gap in the prevention of stroke in AF.

Transcatheter Aortic Valve Implantation in Degenerate Failing Aortic Homograft Root Replacements

To the Editor: As with all bioprosthetic aortic valve substitutes, homografts are prone to late degeneration characterized by dense calcification and valve dysfunction. Reoperation in patients with prior homograft aortic root replacement may carry a substantial risk, particularly in elderly

Stroke prevention using dabigatran in elderly Chinese patients with atrial fibrillation

BACKGROUND Little is known about the clinical benefit of a non-vitamin K antagonist oral anticoagulant compared with warfarin in elderly Chinese patients with atrial fibrillation (AF). OBJECTIVE The purpose of this study was to evaluate the clinical benefit of dabigatran in elderly (age ≥80 years) Chinese patients with nonvalvular AF with regard to the risk of ischemic stroke and intracranial hemorrhage (ICH). METHODS This was an observational study. RESULTS We studied 571 Chinese patients (mean age 84.8 ± 4.0 years; 58.1% women) with nonvalvular AF. The primary outcome was hospital admission for ischemic stroke, and the secondary outcome was admission for ICH. The mean CHA2DS2-VASc (congestive heart failure [1 point], hypertension [1 point], age 65-74 years [1 point] and age ≥75 years [2 points], diabetes mellitus [1 point], prior stroke or transient ischemic attack [2 points], vascular disease [1 point], sex category [female] [1 point]) and HAS-BLED (hypertension [1 point], abnormal renal/liver function [1 point], stroke [1 point], bleeding history [1 point] or predisposition [1 point], labile international normalized ratio [1 point], elderly [age >65 years] [1 point], drugs/alcohol concomitantly [1 point]) scores were 4.8 ± 1.6 and 2.4 ± 0.8, respectively. Of 571 patients, 129 (22.6%) were taking dabigatran 110 mg twice daily and the remaining were on warfarin. After a mean follow-up of 2.6 years (a total of 1471 patient-years), ischemic stroke occurred in 83 patients on warfarin (6.9% per year) compared with 4 patients on dabigatran (1.4% per year) (hazard ratio 0.22; 95% confidence interval 0.23-0.67). There were 8 incidences of ICH: 7 in patients on warfarin (0.59% per year) and 1 patient on dabigatran (0.35% per year). Dabigatran was associated with a substantially lower ischemic stroke risk (1.4% per year vs 5.4% per year) and similar ICH risk (0.35% per year vs 0.36% per year) as compared with warfarin with time in therapeutic range (TTR) ≥55%. CONCLUSION In elderly Chinese patients with AF, this study suggested that dabigatran achieved superior stroke risk reduction and similar risk of ICH compared with warfarin with TTR ≥55%. Dabigatran may be preferable to warfarin in elderly patients with AF for stroke prevention, particularly in those with poor TTR.