Swee-Guan Teo

Obstructive Sleep Apnea in Patients Admitted for Acute Myocardial Infarction: Prevalence, Predictors, and Effect on Microvascular Perfusion

BACKGROUND We investigated the prevalence and predictors of obstructive sleep apnea (OSA) in patients admitted to the hospital for acute myocardial infarction and whether OSA has any association with microvascular perfusion after primary percutaneous coronary intervention (PCI). METHODS Recruited patients were scheduled to undergo an overnight sleep study between 2 and 5 days after primary PCI. An apnea-hypopnea index (AHI) of > or = 15 was considered diagnostic of OSA. Impaired microvascular perfusion after primary PCI was defined as an ST-segment resolution of < or = 70%, myocardial blush grade 0 or 1, or a corrected Thrombolysis in Myocardial Infarction (TIMI) [antegrade flow scale] frame count > 28. RESULTS Sleep study was performed in 120 patients and completed in 105 patients (study cohort, mean age 53 +/- 10 years, male 98%) with uncomplicated myocardial infarction. An AHI was > or = 15 in 69 patients (OSA-positive), giving a prevalence of 65.7%. Diabetes mellitus was found to be a significant risk factor for OSA (odds ratio, 2.86; 95% confidence interval, 1.06 to 8.24; p = 0.033). There were no differences between OSA-positive and OSA-negative groups with regard to the percentage of patients with < or = 70% ST-segment resolution (73% vs 64%, respectively; p = 0.411), myocardial blush grade 0 or 1 (39.1% vs 38.9%, respectively; p = 1.000), or corrected TIMI frame count > 28 (21.7% vs 25.0%, respectively; p = 0.807). CONCLUSIONS We found a high prevalence of previously undiagnosed OSA in patients admitted with acute myocardial infarction. Diabetes mellitus was independently associated with OSA. No evidence indicated that OSA is associated with impaired microvascular perfusion after primary PCI.

New Set of Intravascular Ultrasound-Derived Anatomic Criteria for Defining Functionally Significant Stenoses in Small Coronary Arteries (Results from Intravascular Ultrasound Diagnostic Evaluation of Atherosclerosis in Singapore (IDEAS) Study)

We sought to determine the intravascular ultrasound-derived anatomic criteria for functionally significant lesions in small coronary arteries with a reference segment diameter <3 mm. A fractional flow reserve (FFR) of <0.75, as determined by pressure wire using high-dose (100 to 150 microg) intracoronary adenosine, was used as the reference standard for functional significance. For the 94 patients/lesions involved in the present study, the average reference vessel diameter was 2.72 mm. The FFR was <0.75 in 38 patients (40.4%) and > or =0.75 in 56 patients (59.6%). Logistic regression analysis identified the minimal lumen area, plaque burden, and lesion length as the 3 most important determinants of the FFR. Using classification and regression tree analysis, the best cutoff values for these determinants to discriminate a FFR of <0.75 versus > or =0.75 were a minimal lumen area of < or =2.0 mm(2) (sensitivity 82.35%, specificity 80.77%), plaque burden of > or =80% (sensitivity 87.9%, specificity 78.9%), and lesion length of > or =20 mm (sensitivity 63.6%, specificity 78.9%). A significant increase was found in the area under the receiver operating characteristic curve of the combined parameters (minimal lumen area plus plaque burden plus lesion length) compared to the plaque burden (p = 0.014) and other individual parameters (p <0.001). In conclusion, we found that intravascular ultrasound-derived anatomic criteria are able to predict the functional significance of intermediate lesions in small coronary arteries. A minimal lumen area of < or =2.0 mm(2), plaque burden of > or =80%, and lesion length of > or =20 mm predicted a FFR of <0.75 with good sensitivity and specificity.

The long-term predictive value of the neutrophil-to- lymphocyte ratio in Type 2 diabetic patients presenting with acute myocardial infarction

BACKGROUND Patients with diabetes mellitus have worse long-term outcomes after acute myocardial infarction (AMI) than non-diabetics. This may be related to differential contribution of neutrophil and lymphocyte to inflammation during AMI in diabetics vs. non-diabetics. We aim to determine the predictive value of neutrophil-to-lymphocyte ratio (NLR) for major adverse events post-AMI in Type 2 diabetics vs. non-diabetics. METHODS AND RESULTS A total of 2559 consecutive patients admitted for AMI (61 ± 14 years, 73% male and 43% diabetic) were analyzed. A complete blood count was obtained and the NLR computed for each patient on admission. Across the cohort, the 1-year reinfarction rate was 8.4% (n = 214) and 1-year mortality was 14.5% (n = 370). Univariate determinants of the composite endpoint included age, hypertension, hyperlipidemia, smoking, revascularization and NLR (P < 0.001 for all). The cohort was divided into NLR quartiles. Admission NLR was significantly higher in the diabetic group, 5.2 ± 5.8 vs. 4.6 ± 5.4 (P = 0.007). A step-wise increase in the incidence of the composite endpoint was noted across NLR quartiles for diabetic subjects; hazard ratio (HR) was 2.41 for fourth vs. first quartile (95% confidence interval = 1.63-3.53, P < 0.001). Multivariate analysis of the diabetic group showed that NLR remains as an independent predictor of the composite endpoint (adjusted HR = 1.53, 95% confidence interval = 1.00-2.33, P = 0.048). However, in non-diabetics, HR for NLR was not significant (P = 0.35). CONCLUSION Increased NLR post-AMI is an independent predictor of major adverse cardiac events in diabetics. Monitoring this easily obtainable new index allows prognostication and risk stratification.

Two‐Year Clinical Registry Follow‐up of Endothelial Progenitor Cell Capture Stent Versus Sirolimus‐Eluting Bioabsorbable Polymer‐Coated Stent Versus Bare Metal Stents in Patients Undergoing Primary Percutaneous Coronary Intervention for ST Elevation Myocardial Infarction

BACKGROUND Endothelial progenitor cell (EPC) capture stent is designed to promote rapid endothelization and healing and is potentially useful in patients undergoing primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI). We studied the intermediate-term efficacy and safety of EPC stent and compared that with sirolimus-eluting bioabsorbable polymer stent (CURA) and bare metal stent (BMS) in AMI patients. METHODOLOGY Patients presenting with AMI who underwent primary PCI with the respective stents between January 2004 and June 2006 were enrolled in the single-center clinical registry. The study end-points were major adverse cardiac events (MACE) and stent thrombosis. RESULTS A total of 366 patients (EPC = 95, CURA = 53, BMS 218) were enrolled. Baseline demographics including age, gender, diabetes, renal impairment, predischarge left ventricular ejection fraction, and creatinine kinase level were comparable among the groups. Procedural success rate was 99.5%. Post-procedural thrombolysis in myocardial infarction (TIMI) 3 flow was achieved in EPC 91.6%, CURA 96.2%, and BMS 88.5% (P = 0.209). At 2 years, the MACE rate was EPC 13.7%, CURA 15.1%, and BMS 19.7% (P = 0.383). Target vessel revascularizations (TVR) were EPC 4.2%, CURA 9.4%, and BMS 6.0% (P = 0.439). Nonfatal myocardial infarctions were EPC 1.1%, CURA 3.8%, and BMS 4.1% (P = 0.364). One patient in the EPC group had acute stent thrombosis. There was no late stent thrombosis in the EPC group. CONCLUSION EPC stent appeared to be safe and had comparable clinical efficacy with a BMS when used in the AMI setting. At 2-year follow-up, the EPC group showed favorable, single-digit TVR rate and stent thrombosis remained a low-event occurrence.

Shortening of Median Door‐to‐Balloon Time in Primary Percutaneous Coronary Intervention in Singapore by Simple and Inexpensive Operational Measures: Clinical Practice Improvement Program

BACKGROUND Primary percutaneous coronary intervention is the standard reperfusion strategy for ST-segment elevation myocardial infarction in our center. We aimed to shorten the median door-to-balloon time from over 100 minutes to 90 minutes or less. METHODS We have been using three strategies since March 2007 to shorten the door-to-balloon time: (1) the intervention team is now activated by emergency department physicians (where previously it had been activated by coronary care unit); (2) all members of the intervention team have converted from using pagers to using cell phones; and (3) as soon as the intervention team is activated, patients are transferred immediately to the cardiac catheterization laboratory (where previously they had waited in the emergency department for the intervention team to arrive). An in-house physician and a nurse would stay with the patients before arrival of the intervention team. RESULTS During 12 months, 285 nontransfer patients (analyzed, n = 270) underwent primary PCI. The shortest monthly median door-to-balloon time was 59 minutes; the longest monthly median door-to-balloon time was 111 minutes. The overall median door-to-balloon time for the entire 12 months was 72 minutes. On a per-month basis, the median door-to-balloon time was 90 minutes or less in 10 of 12 months. On a per-patient basis, the median door-to-balloon time was 90 minutes or less in 182 patients (67.4%). There was 1 case (0.4%) of inappropriate activation by the emergency department. While waiting for the intervention team to convene, 1 patient (0.4%) deteriorated and had to be resuscitated in the cardiac catheterization laboratory. CONCLUSIONS Improved health care delivery can be achieved by changing simple and inexpensive operational processes.

Effectiveness and Safety of the Genous Endothelial Progenitor Cell-Capture Stent in Acute ST-Elevation Myocardial Infarction

The endothelial progenitor cell (EPC)-capture stent promotes endothelialization and preliminary studies have suggested its safety and feasibility in ST-elevation myocardial infarction (STEMI). Detailed late clinical follow-up and angiographic analyses are, however, limited. We sought to determine late angiographic and clinical outcomes of the Genous EPC-capture stent in primary angioplasty. EPC-capture stents were implanted during primary angioplasty in 489 consecutive patients presenting with STEMI from 2004 through 2008. The first 100 consenting patients undergoing successful stent implantation scheduled to undergo relook coronary angiography at 6 to 12 months were enrolled. Ninety-five patients with 96 lesions were analyzed independently. Mean duration of follow-up coronary angiography was 245 days. In-stent late luminal loss measured 0.87 ± 0.67 mm. Binary restenosis (defined as >50% diameter stenosis) was 28%, with diffuse in-stent restenosis (Mehran class II) as the predominant pattern. Of 27 patients with binary restenosis, 14 (52%) were symptomatic, with 10 patients undergoing target lesion revascularization. Asymptomatic patients had significantly larger reference vessel and in-stent minimal luminal diameters (2.77 ± 0.39 vs 2.54 ± 0.44 mm, p = 0.040; 2.74 ± 0.34 vs 2.31 ± 0.72 mm, p = 0.004, respectively). Follow-up late loss and diameter stenoses were also in favor of the asymptomatic group. Major adverse cardiac event rate was 16% at a mean follow-up of 34 months. There were no cases of Academic Research Consortium-defined stent thrombosis. In conclusion, implantation of the EPC-capture stent during primary angioplasty is associated with a favorable late clinical outcome but with higher than anticipated angiographic late loss.

Initial experience in the clinical use of everolimus-eluting bioresorbable vascular scaffold (BVS) in a single institution

We read with great interest the recent review article on bioresorbable vascular scaffolds by Bourantas et al. and wish to share our institutions experience with the use of the ABSORB bioresorbable vascular scaffold (BVS; Abbott Vascular, Santa Clara, California) [1]. There is currently limited published data on the use of BVS in routine clinical practice andwehaveundertaken a prospective evaluation of this novel device in our institution. All consecutive patients who underwent percutaneous coronary intervention (PCI) with intent for BVS implantation between July 2011 and September 2012were included in the analysis. All patients received dual anti-platelet therapyprior to PCI and this therapywascontinued for at least a year after implantation. This study fulfilled local ethical requirements and written informed consent was obtained from all patients. The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology. Once a suitable lesion was identified, the pre-procedural reference vessel diameter (RVD) was assessed by quantitative coronary analysis (QCA) using the Pie Medical CAAS QCA (quantitative coronary analysis) package in our Xcelera Workstations (Philips Medical Systems, Veenpluis, The Netherlands). Alternative vessel sizing was via the use of commercially available intravascular ultrasound (IVUS) or optical coherence tomography (OCT). A RVD of 2.0 to 3.8 mm and a lesion length of less than 28 mm were considered suitable for BVS (single or overlapping). The availableABSORBBVSwere2.5×18 mm,2.5×28 mm, 3.0×18 mm, 3.0×28 mm, 3.5×12 mm, 3.5×18 mm, or 3.5×28 mm in size. 6 Fr vascular access was used in all patients with a predominant radial access (77.1%). Mandatory predilation with balloon angioplasty using a balloon with a diameter of 0.5 mm smaller or equivalent to the intended BVS size was performed prior to BVS implantation. Device deployment was performed at a rate of ≤2 atm per 5 s up to 16 atm (rated burst pressure). Postdilation was with a non-compliant balloon with diameter≤0.25 mm beyond the implanted BVS if necessary to avoid scaffold damage. For longer lesions or edge dissections, overlapping scaffolds were used. A total of 35 consecutive patients with 41 lesions underwent attempted ABSORB BVS implantation during the study period. Baseline emographics, indications, procedure and quantitative coronary angiography details are summarized in Table 1. The mean age is 54.7± 11.2 years (range 36–86 years) and 85.7% of the patients (n=30) were male. Diabetes mellitus (type I or II) was present in 17.1% (n=6) of the study population. 51.4% of patients presented with an acute coronary syndrome including unstable angina, non-ST elevation myocardial infarction (NSTEMI), and ST elevation myocardial infarction (STEMI). Overall, 45 BVS were successfully implanted in 33 (93.3%) patients (1.4 BVS/patient). Of the 41 lesions treated, the success rate was 100% (22/22) for the left anterior descending artery (LAD), 100% (11/11) for the right coronary artery (RCA), and 75% (6/8) for the left circumflex artery (LCX). Two patients had circumflex (LCX) stenosis not crossable by the BVS despite aggressive lesion preparation with multiple balloon predilations. An equivalent metallic drug eluting stent crossed without difficulty in both cases. The majority, 31 (75.6%), of lesions treated were complex (B2 or C). Pre-procedure RVD was assessed by QCA in 28 patients (80.0%), IVUS in 4 patients (11.4%), andOCT in 3 patients (8.6%). Themeanpre-procedural RVDwas 2.7±0.4 mm, diameter stenosiswas 77.7±13.0%, and lesion lengthwas 17.2±6.7 mm. Post-procedural RVD was 3.0±0.3 mmwith residual diameter stenosis of 2.4±2.0%.

Prevalence and predictors of premature discontinuation of dual antiplatelet therapy after drug-eluting stent implantation: importance of social factors in Asian patients

Aim:  Premature discontinuation of antiplatelet therapy is an independent predictor of late stent thrombosis. We sought to determine the prevalence and predictors of premature discontinuation of antiplatelet therapy after drug‐eluting stent implantation among patients in Asia.

Relation between door-to-balloon time and microvascular perfusion as evaluated by myocardial blush grade, corrected TIMI frame count, and ST-segment resolution in treatment of acute myocardial infarction.

BACKGROUND The role of microvascular perfusion in relation to door-to-balloon time and mortality remains unknown. We sought to compare microvascular perfusion in patients who had undergone primary percutaneous coronary intervention with door-to-balloon time < or =90 minute versus >90 minutes. METHODS Using myocardial blush grade (MBG), corrected TIMI frame count (CTFC), and ST-segment resolution, microvascular perfusion was assessed in 297 patients who underwent successful primary percutaneous coronary intervention between January 2007 and April 2008. RESULTS Door-to-balloon time was < or =90 minutes in 199 (67%) patients and >90 minutes in 98 (33%) patients. Univariate analysis showed that door-to-treatment >90 minutes was associated with MBG 0/1 and CTFC >28. However, it was not associated with ST-segment resolution < or =70%. After adjustment for baseline confounding factors, door-to-balloon time >90 minutes was still associated with MBG 0/1 (adjusted OR 3.20, 95% CI 1.87 to 5.49, P < 0.001) and CTFC >28 (adjusted OR 6.30, 95% CI 3.56 to 11.17, P < 0.001). Thirty-day mortality was higher in patients with longer door-to-balloon time (adjusted OR 2.87, 95% CI 0.94 to 8.77, P = 0.064). CONCLUSION We found that door-to-balloon time >90 minutes, compared with < or =90 minutes, was independently associated with MBG 01/2 and CTFC >28, both suggesting microvascular obstruction. However, such association was not found in ST-segment resolution. Patients with door-to-balloon time >90 minutes also had higher 30-day mortality.

Utilisation of emergency medical service among Singapore patients presenting with ST-segment elevation myocardial infarction: prevalence and impact on ischaemic time.

Background:  Previous studies in Western countries found that the emergency medical service (EMS) was under‐used in patients with myocardial infarction.