Jack Wei Chieh Tan

Infected Coronary Artery Pseudoaneurysm After Repeated Percutaneous Coronary Intervention

Coronary stent infection is exceedingly rare, with only 23 reported cases. We present a patient with an everolimus-coated stent infection that led to an infected pseudoaneurysm in the left anterior descending artery. Medical therapy failed and the patient underwent emergent surgical intervention; however, he died of multiorgan failure after the operation.

Simplified Models of Non-Invasive Fractional Flow Reserve Based on CT Images.

Invasive fractional flow reserve (FFR) is the gold standard to assess the functional coronary stenosis. The non-invasive assessment of diameter stenosis (DS) using coronary computed tomography angiography (CTA) has high false positive rate in contrast to FFR. Combining CTA with computational fluid dynamics (CFD), recent studies have shown promising predictions of FFRCT for superior assessment of lesion severity over CTA alone. The CFD models tend to be computationally expensive, however, and require several hours for completing analysis. Here, we introduce simplified models to predict noninvasive FFR at substantially less computational time. In this retrospective pilot study, 21 patients received coronary CTA. Subsequently a total of 32 vessels underwent invasive FFR measurement. For each vessel, FFR based on steady-state and analytical models (FFRSS and FFRAM, respectively) were calculated non-invasively based on CTA and compared with FFR. The accuracy, sensitivity, specificity, positive predictive value and negative predictive value were 90.6% (87.5%), 80.0% (80.0%), 95.5% (90.9%), 88.9% (80.0%) and 91.3% (90.9%) respectively for FFRSS (and FFRAM) on a per-vessel basis, and were 75.0%, 50.0%, 86.4%, 62.5% and 79.2% respectively for DS. The area under the receiver operating characteristic curve (AUC) was 0.963, 0.954 and 0.741 for FFRSS, FFRAM and DS respectively, on a per-patient level. The results suggest that the CTA-derived FFRSS performed well in contrast to invasive FFR and they had better diagnostic performance than DS from CTA in the identification of functionally significant lesions. In contrast to FFRCT, FFRSS requires much less computational time.

Invasive Assessment of the Coronary Microcirculation in Reperfused ST-Segment–Elevation Myocardial Infarction Patients: Where Do We Stand?

For patients presenting with an acute ST-segment–elevation myocardial infarction, the most effective therapy for reducing myocardial infarct size and preserving left ventricular systolic function is primary percutaneous coronary intervention (PPCI). However, mortality and morbidity remain significant. This is partly attributed to the development of microvascular obstruction, which occurs in around 50% of ST-segment–elevation myocardial infarction patients post-PPCI, and it is associated with adverse left ventricular remodeling and worse clinical outcomes. Although microvascular obstruction can be detected by cardiac imaging techniques several hours post-PPCI, it may be too late to intervene at that time. Therefore, being able to predict the development of microvascular obstruction at the time of PPCI may identify high-risk patients who might benefit from further adjuvant intracoronary therapies, such as thrombolysis, vasodilators, glycoprotein IIb/IIIa inhibitors, and anti-inflammatory agents that may reduce microvascular obstruction. Recent studies have shown that invasive coronary physiology measurements performed during PPCI can be used to assess the coronary microcirculation. In this article, we provide an overview of the various invasive methods currently available to assess the coronary microcirculation in the setting of ST-segment–elevation myocardial infarction, and how they could potentially be used in the future for tailoring therapies to those most at risk.

Index of Microvascular Resistance and Microvascular Obstruction in Patients With Acute Myocardial Infarction

Despite timely reperfusion by primary percutaneous coronary intervention (PPCI), microvascular obstruction (MVO) occurs in up to 50% of patients with ST-segment elevation myocardial infarction (STEMI) [(1)][1]. Its presence is associated with adverse left ventricular remodeling and worse clinical

Long-term outcomes after coronary bare-metal-stent and drug-eluting-stent implantations: a 'real-world' comparison among patients with diabetes with diffuse small vessel coronary artery disease.

Background and aimDrug-eluting stents (DESs) have been reported to be more efficacious compared with bare-metal stents (BMSs) in reducing the need for target vessel revascularization (TVR). However, the long-term benefits for patients with diabetes with small vessel disease are less certain. We aim to determine the clinical outcome of patients with diabetes with diffuse small vessel coronary artery disease who undergo percutaneous coronary intervention. MethodsThis is a single-center prospective registry of all patients with diabetes with target lesions implanted with stents that were 2.25 mm or less in diameter and approximately 20 mm in total stent length between January 2002 and October 2008. Primary outcome was combined major adverse cardiovascular events: death, nonfatal myocardial infarction and TVR up to 5 years. Outcomes were adjusted for age, sex and cardiovascular risk factors. ResultsThere were 544 patients (63% males, mean age 62±10 years) with 1010 lesions that were followed up for a mean duration of 3±2 years. Two hundred and thirty-nine patients (439 lesions) received BMS whereas 305 (571 lesions) received DES. DES lesions were longer (mean length 23.3±6.96 vs. 17.8±5.02 mm, P<0.001) than BMS lesions. Procedural success was similar for BMS and DES patients (86.2 vs. 86.6%, P=0.90). DES patients had less TVR at 6 months [3.9 vs. 9.2%, odds ratio (OR): 4.90, 95% confidence interval (CI): 1.53–15.65, P=0.007], 1 year (1 vs. 3.8%, OR: 8.01, 95% CI: 1.25–51.10, P=0.028) and3 years (13.8 vs. 18.0%, OR: 5.50, 95% CI: 3.74–8.13, P=0.043). By 5 years, the primary outcome was lower in DES patients (21.6 vs. 28%, OR: 1.79, 95% CI: 1.14–2.80, P=0.011). Independent predictors of TVR at 6 months were above or equal to 59 years of age (OR: 0.95, 95% CI: 0.90–1.00, P=0.032) and use of glycoprotein-IIbIIIa inhibitors (OR: 0.02, 95% CI: 0.001–0.50, P=0.018). Stent length was not a significant predictor of TVR. ConclusionOur observational analysis suggests that DES seems to have short-term and mid-term advantages over BMS in reducing TVR and overall major adverse cardiovascular events. Percutaneous coronary intervention with DES may be considered as an option in these patients with limited revascularization options.

Percutaneous coronary intervention in asians- are there differences in clinical outcome?

BackgroundEthnic differences in clinical outcome after percutaneous coronary intervention (PCI) have been reported. Data within different Asian subpopulations is scarce. We aim to explore the differences in clinical profile and outcome between Chinese, Malay and Indian Asian patients who undergo PCI for coronary artery disease (CAD).MethodsA prospective registry of consecutive patients undergoing PCI from January 2002 to December 2007 at a tertiary care center was analyzed. Primary endpoint was major adverse cardiovascular events (MACE) of myocardial infarction (MI), repeat revascularization and all-cause death at six months.Results7889 patients underwent PCI; 7544 (96%) patients completed follow-up and were included in the analysis (79% males with mean age of 59 years ± 11). There were 5130 (68%) Chinese, 1056 (14%) Malays and 1001 (13.3%) Indian patients. The remaining 357 (4.7%) patients from other minority ethnic groups were excluded from the analysis. The primary end-point occurred in 684 (9.1%) patients at six months. Indians had the highest rates of six month MACE compared to Chinese and Malays (Indians 12% vs. Chinese 8.2% vs. Malays 10.7%; OR 1.55 95%CI 1.24-1.93, p < 0.001). This was contributed by increased rates of MI (Indians 1.9% vs. Chinese 0.9% vs. Malays 1.3%; OR 4.49 95%CI 1.91-10.56 p = 0.001), repeat revascularization (Indians 6.5% vs. Chinese 4.1% vs. Malays 5.1%; OR 1.64 95%CI 1.22-2.21 p = 0.0012) and death (Indians 11.4% vs. Chinese 7.6% vs. Malays 9.9%; OR 1.65 95%CI 1.23-2.20 p = 0.001) amongst Indian patients.ConclusionThese data indicate that ethnic variations in clinical outcome exist following PCI. In particular, Indian patients have higher six month event rates compared to Chinese and Malays. Future studies are warranted to elucidate the underlying mechanisms behind these variations.

Comparing the use of cobalt chromium stents to stainless steel stents in primary percutaneous coronary intervention for acute myocardial infarction: A prospective registry

Objectives: To determine clinical outcome and rates of target vessel revascularization (TVR) in patients undergoing primary percutaneous coronary intervention (PCI) for STEMI who were treated with cobalt-chromium stents compared to stainless steel bare metal stents (BMS). Background: The newer generation cobalt chromium stents were reported to achieve lower rates of TVR compared with conventional BMS. Methods: Consecutive STEMI cases admitted within 12 h of symptom onset and undergoing primary angioplasty and bare metal stent implantation 1 January 2002 and 31 December 2008 were identified. Primary outcomes were rates of clinically-driven TVR at six months as well as occurrence of major adverse cardiovascular events (MACE) either of all-cause death, repeat myocardial infarction or TVR at six months. Results: 1030 cases with 1175 lesions (84% males) and median age of 58 years underwent primary PCI for STEMI in our registry. Overall procedural success rate was 98%. Stainless steel stents were inserted in 65% of the culprit lesions (stainless steel, n = 766 versus cobalt chromium, n = 264). Primary outcomes of TVR (3.5% in the stainless steel group and 3.4% in the cobalt chromium group, P = 0.93) and MACE (8.4% in the stainless steel group and 5.3% in the cobalt chromium group, P = 0.11) after six months were no different between the two groups. However, there were more deaths at 30 days in the stainless steel group compared to the cobalt chromium group (3.5% versus 0.4%, HR 4.04 (1.03–3.88), P = 0.04). Conclusion: Both cobalt-chromium and stainless steel coronary stents were associated with similar and low risk of clinically-driven TVR.

Advanced analyses of computed tomography coronary angiography can help discriminate ischemic lesions

BACKGROUND Computed tomography coronary angiography (CTCA) image analysis enables plaque characterization and non-invasive fractional flow reserve (FFR) calculation. We analyzed various parameters derived from CTCA images and evaluated their associations with ischemia. METHODS 49 (61 lesions) patients underwent CTCA and invasive FFR. Lesions with diameter stenosis (DS) ≥ 50% were considered obstructive. CTCA image processing incorporating analytical and numerical methods were used to quantify anatomical parameters of lesion length (LL) and minimum lumen area (MLA); plaque characteristic parameters of plaque volume, low attenuation plaque (LAP) volume, dense calcium volume (DCV), normalized plaque volume (NP Vol), plaque burden, eccentricity index and napkin-ring (NR) sign; and hemodynamic parameters of resistance index, stenosis flow reserve (SFR) and FFRB. Ischemia was defined as FFR ≤ 0.8. RESULTS Plaque burden and plaque volume were inversely related to FFR. Multivariable logistic regression analysis identified the best anatomical, plaque and hemodynamic predictors, respectively, as DS (≥50% vs <50%; OR: 8.0; 95% CI: 1.6-39.4), normalized plaque volume (NP Vol) (≥4.3 vs <4.3; OR: 3.9; 95% CI: 1.1-14.0) and NR Sign (0 vs 1; OR: 13.6; 95% CI: 1.3-146.1), and FFRB (≤0.8 vs >0.8; OR: 44.4; 95% CI: 8.8-224.8). AUC increased from 0.70 with DS as the sole predictor to 0.81 after adding NP Vol and NR Sign; further addition of FFRB increased AUC to 0.93. CONCLUSION Normalized plaque volume, napkin-ring derived from plaque analysis, and FFRB from numerical simulations on CTCA images substantially improved discrimination of ischemic lesions, compared to assessment by DS alone.

Review of the Clinical Evidence and Controversies in Therapeutic Hypothermia for Survivors of Sudden Cardiac Death

Sudden cardiac arrest constitutes a major public health burden in both developed and developing countries. In those successfully resuscitated from cardiac arrest, subsequent mortality is still high (∼75%) and is due to a combination of ischaemia and reperfusion injury. The purpose of this review is to describe the experimental and clinical evidence supporting therapeutic hypothermia in survivors of sudden cardiac arrest. We also discuss controversies and unresolved issues in therapeutic hypothermia, including the optimum target temperature for therapeutic hypothermia, and the role of pre-hospital induction of hypothermia. We conclude with a perspective on therapeutic hypothermia as it applies to the Singapore context.

Trans-pleural pericardiocentesis: revisiting an old technique.

Percutaneous access to the pericardial space serves both diagnostic and therapeutic purposes. Multiple approaches have been described, which include the apical, sub‐xiphoid, trans‐atrial, and trans‐bronchial techniques. Occasionally, in the presence of both left pleural effusion and posterior pericardial effusion, echocardiographically guided pleuropericardial drainage can be carried out using the left axillary approach. Here we revisit the use of this technique in a patient. Future development of this technique, using a noncompliant balloon to expand the pleuropericardial interface, may avoid the need for a pericardial window in oncology and rheumatology patients with recurrent pericardial effusions.