Yeo's index: A novel index that combines anatomic and haemodynamic assessment of the severity of mitral stenosis.

BACKGROUND: A mitral leaflet separation index (MLSI), measuring the anatomical separation of the mitral valve (MV) leaflet tips in diastole, was previously described as an accurate method of assessing mitral stenosis (MS). We propose a novel modification of the MLSI by including a hemodynamic assessment which we term Yeo's index that may improve its diagnostic performance. METHODS AND RESULTS: We retrospectively studied 174 patients with varying severity of MS without significant mitral regurgitation, aortic valve disease or ventricular septal defect. MLSI was measured in 2 orthogonal views on transthoracic echocardiography as previously described. MV dimensionless index (DI) was calculated by dividing the left ventricular outflow tract pulsed-wave Doppler time velocity integral (TVI) by the MV continuous-wave Doppler TVI. We defined Yeo's index as the product of MLSI and DI. With linear correlation, Yeo's index demonstrated good correlation against MVA by planimetry (r = 0.728), pressure half-time (r = 0.677), and continuity equation (r = 0.829), with improved performance over the MLSI. Using ROC analysis, Yeo's index demonstrated good ability to correctly classify MS as severe (MVA ≤1.5cm2) (AUC 0.874, 95% CI 0.816-0.920). Yeo's index ≤0.260 cm correctly classified severe MS with sensitivity of 82% and specificity of 80%. Presence of AF did not affect the performance of Yeo's index. Yeo's index ≤0.147 cm also identified very severe MS (MVA ≤ 1.0 cm2) with specificity of 94% and sensitivity of 78%. CONCLUSION: Yeo's index performed well in identifying severe MS and may be a useful adjunct to existing measures of MS severity.

Cost-Effectiveness of Transcatheter Aortic Valve Implantation in Intermediate and Low Risk Severe Aortic Stenosis Patients in Singapore.

INTRODUCTION: Singapore has the world's second most efficient healthcare system while costing less than 5% GDP. It remains unclear whether transcatheter aortic valve implantation (TAVI) is cost-effective for treating intermediate-low risk severe aortic stenosis (AS) patients in a highly efficient healthcare system. MATERIALS AND METHODS: A two-phase economic model combining decision tree and Markov model was developed to assess the costs, effectiveness, and the incremental cost-effectiveness ratio (ICER) of transfemoral (TF) TAVI versus surgical aortic valve replacement (SAVR) in intermediate-low risk patients over an 8-year time horizon. Mortality and complications rates were based on PARTNER 2 trial cohort A and Singapore life table. Costs were mainly retrieved from Singapore National University Health System database. Health utility data were obtained from Singapore population based on the EuroQol-5D (EQ-5D). A variety of sensitivity analyses were conducted. RESULTS: In base case scenario, the incremental effectiveness of TF-TAVI versus SAVR was 0.19 QALYs. The ICER of TF-TAVI was S$33,833/QALY. When time horizon was reduced to 5 years, the ICER was S$60,825/QALY; when event rates from the propensity analysis was used, the ICER was S$21,732/QALY and S$44,598/QALY over 8-year and 5-year time horizons, respectively. At a willingness to pay threshold of S$73,167/QALY, TF-TAVI had a 98.19% probability of being cost-effective after 100,000 simulations. The model was the most sensitive to the costs of TF-TAVI procedure. CONCLUSION: TF-TAVI is a highly cost-effective option compared to SAVR for intermediate-low risk severe AS patients from a Singapore healthcare system perspective. Increased procedure experience, reduction in device cost, and technology advance may have further increased the cost-effectiveness of TF-TAVI per scenario analysis.

Cost-effectiveness analysis of biodegradable polymer versus durable polymer drug-eluting stents incorporating real-world evidence.

AIM: Compared with second-generation durable polymer drug-eluting stents (DP-DES), the cost-effectiveness of biodegradable polymer drug-eluting stents (BP-DES) remains unclear in the real-world setting. We assessed the cost-effectiveness of BP-DES in patients with coronary artery disease undergoing percutaneous coronary intervention (PCI). METHODS: We developed a decision-analytic model to compare the cost-effectiveness of BP-DES to DP-DES over 1 year and 5 years from healthcare payer perspective. Relative treatment effects during the first year post-PCI were obtained from a real-world population analysis while clinical event risks in the subsequent 4 years were derived from a meta-analysis of published studies. RESULTS: At 1 year, based on the clinical data analysis of 497 propensity-score matched pairs of patients, BP-DES were associated with an incremental cost-effectiveness ratio (ICER) of USD20 503 per quality-adjusted life-year (QALY) gained. At 5 years, BP-DES yielded an ICER of USD4062 per QALY gained. At the willingness-to-pay threshold of USD50 400 (one gross domestic product per capita in Singapore in 2015), BP-DES were cost-effective. Sensitivity analysis showed that the cost of stents had a significant impact on the cost-effectiveness of BP-DES. Threshold analysis demonstrated that if the cost difference between BP-DES and DP-DES exceeded USD493, BP-DES would not be cost-effective in patients with 1 year of follow-up. CONCLUSIONS: Biodegradable polymer drug-eluting stents were cost-effective compared with DP-DES in patients with coronary artery disease at 1 year and 5 years after PCI. It is worth noting that the cost of stents had a significant impact on the findings.

Assessment of left atrial appendage function by transthoracic pulsed Doppler echocardiography: Comparing against transesophageal interrogation and predicting echocardiographic risk factors for stroke.

AIMS: Transesophageal echocardiographic (TEE) findings of left atrial appendage (LAA) thrombus, spontaneous echo contrast (SEC), and LAA dysfunction are established risk factors of cardioembolic stroke. The semi-invasive nature of TEE limits its utility as a routine risk stratification tool. We aim to correlate TEE and transthoracic echocardiography (TTE) pulsed Doppler measurements of LAA flow velocities and use TTE measurements to predict TEE findings. METHODS AND RESULTS: We prospectively measured pulsed Doppler LAA flow velocities in 103 consecutive patients on TEE and TTE. There was a strong correlation between TEE and TTE LAA emptying velocity (LAA E) (r = .88, P < .001) and a moderate correlation between LAA filling velocities (r = .50, P < .001). TTE LAA E predicted the presence of thrombus or SEC independent of atrial fibrillation (AF). To predict the presence of thrombus or SEC, the optimal TTE LAA E cutoff was ≤30 cm/s in all patients (75% sensitive, 90% specific) and ≤31 cm/s in AF patients (80% sensitive, 79% specific). To predict LAA dysfunction (TEE E ≤ 20 cm/s), the optimal TTE LAA E cutoff was ≤27 cm/s (100% sensitive, 89% specific in all patients and 100% sensitive, 74% specific in AF patients). CONCLUSIONS: TTE assessment of LAA function is feasible and correlates well with the more invasive TEE method. It predicts the presence of thrombus, SEC, and LAA dysfunction on TEE. TTE LAA assessment has incremental value in thromboembolic risk stratification and should be utilized more frequently.

Sex Differences in Phenotypes of Bicuspid Aortic Valve and Aortopathy: Insights From a Large Multicenter, International Registry.

BACKGROUND: This large multicenter, international bicuspid aortic valve (BAV) registry aimed to define the sex differences in prevalence, valve morphology, dysfunction (aortic stenosis/regurgitation), aortopathy, and complications (endocarditis and aortic dissection). METHODS AND RESULTS: Demographic, clinical, and echocardiographic data at first presentation of 1992 patients with BAV (71.5% men) were retrospectively analyzed. BAV morphology and valve function were assessed; aortopathy configuration was defined as isolated dilatation of the sinus of Valsalva or sinotubular junction, isolated dilatation of the ascending aorta distal to the sinotubular junction, or diffuse dilatation of the aortic root and ascending aorta. New cases of endocarditis and aortic dissection were recorded. There were no significant sex differences regarding BAV morphology and frequency of normal valve function. When presenting with moderate/severe aortic valve dysfunction, men had more frequent aortic regurgitation than women (33.8% versus 22.2%, P<0.001), whereas women were more likely to have aortic stenosis (34.5% versus 44.1%, P<0.001). Men had more frequently isolated dilatation of the sinus of Valsalva or sinotubular junction (14.2% versus 6.7%, P<0.001) and diffuse dilatation of the aortic root and ascending aorta (16.2% versus 7.3%, P<0.001) than women. Endocarditis (4.5% versus 2.5%, P=0.037) and aortic dissections (0.5% versus 0%, P<0.001) occurred more frequently in men. CONCLUSIONS: Although there is a male predominance among patients with BAV, men with BAV had more frequently moderate/severe aortic regurgitation at first presentation compared with women, whereas women presented more often with moderate/severe aortic stenosis compared with men. Furthermore, men had more frequent aortopathy than women.

Long-term Cost-effectiveness of Statin Treatment for Primary Prevention of Cardiovascular Disease in the Elderly.

PURPOSE: This study aimed to evaluate the cost-effectiveness of statins for primary prevention of stroke and myocardial infarction (MI) in the elderly in Singapore. METHODS: A Markov model was developed to investigate the lifetime costs, quality-adjusted life years (QALYs) and incremental cost-effectiveness ratios (ICERs) of statin treatment in those aged 65 years and older without a history of stroke or MI from the perspective of Singapore's healthcare system, using elderly-specific clinical data and local costs from hospital databases. A lifetime horizon was used and all costs and health outcomes were discounted at 3% annually. RESULTS: In the base-case analysis, statin treatment prevented an additional four strokes and eight MIs among 1,000 "healthy" elderly individuals compared with no treatment. Statin treatment resulted in a QALY gain of 0.26 and additional costs of SGD 11,314 per person, yielding an ICER of SGD 43,925 (USD 33,495) per QALY gained. The results were sensitive to statin effectiveness, particularly statins' effect on all-cause mortality, and cost of statin medication. Probabilistic sensitivity analysis demonstrated that the probability of statin treatment being cost-effective was 72% at a willingness-to-pay threshold of SGD 65,000 (USD 49,546) per QALY gained. Shortening the time horizon from lifetime to 10 years (simulating limited life expectancy) considerably increased the ICER to SGD 291,313 (USD 167,171) per QALY. Female gender and younger age were also associated with higher ICERs owing to a lower baseline risk of cardiovascular disease (CVD) and higher costs to manage events in these subgroups. CONCLUSIONS: Statin treatment for the primary prevention of CVD in the elderly was cost-effective. However, treatment warrants re-evaluation when the prognosis of the individual is considered less than ten years; other goals may take precedence over CVD prevention.

Immigrant status and disparities in health care delivery in patients with myocardial infarction.

BACKGROUND: We investigated the differences in socioeconomic status and quality health care between Singapore-born citizens and immigrants presenting with ST-segment elevation myocardial infarction (STEMI). METHODS: In a prospective study, patients admitted with STEMI were recruited for a questionnaire survey. The recruited patients were categorized based on their immigration status into Singapore-born citizens (SBC), foreign-born citizens (FBC), permanent residents (PR) and non-residents (NR). RESULTS: Among the 374 recruited patients, 286 (76.5%) patients were categorized as SBC, and the remaining 88 (23.5%) as immigrants. Further breakdown of the immigrants revealed that 33 were FBC (median duration of living in Singapore, 53 years), 22 were PR (18 years), and 33 were NR (11 years). Significant differences in socioeconomic status among SBC, FBC, PR and NR were detected. NR were in the lowest, while PR in the highest, socioeconomic class based on occupation (p=0.003), education level (p<0.001), and average monthly household income (p=0.020). There were no disparities in the proportion of patients treated with primary PCI (SBC 88%, FBC 82%, PR 91%, NR 79%, p=0.555). Median door-to-balloon times were similar among the four groups (56, 52, 60, 56min, p=0.614). Compared with SBC, PR was associated with longer symptom-to-balloon times (median difference 54.1 min; 95% CI 9.0 to 99.2). CONCLUSION: There were major differences in the socioeconomic status among SBC, FBC, PR and NR who presented with STEMI. Although there were no major disparities in access to high quality health care to these patients with different immigration status, symptom-to-balloon time differed substantially among the different migrant classes.

Diagnostic utility, safety, and cost-effectiveness of emergency department-initiated early scheduled technetium-99m single photon emission computed tomography imaging followed by expedited outpatient cardiac clinic visits in acute chest pain syndromes.

Conventional emergency department (EMD) approach to triaging acute chest pain syndromes may lead to unnecessary admissions, resulting to in-hospital bed occupancy and increased healthcare costs. We explore the diagnostic utility of early (less than a week) outpatient scheduled single photon emission computed tomography (SPECT) in intermediate-risk chest pain subjects who presented to EMD with non-diagnostic electrocardiogram and negative serum troponin level. Additionally, we intend to study the safety and cost-effectiveness of such a strategy. We conduct a prospective, non-randomized study of 108 subjects who fit the inclusion criteria. After SPECT studies, all subjects were evaluated in the cardiac clinic within 2 weeks of EMD visits. Final diagnosis of coronary artery disease and subsequent disposition to standard medical therapy or follow-on angiography were decided by incorporating pre-test clinical data and SPECT results. Adverse events defined as myocardial infarction and cardiac death was tracked between EMD visit and eventual therapy (either medical therapy or coronary revascularization). Finally, cost-effectiveness was determined based on estimated cost and days of hospitalization saved between standard strategies of ward admission for further evaluation versus the present early outpatient SPECT-based workflow. Among 108 subjects (mean age 58 years, 59% male) included for analysis, 82 (76%) had normal perfusion status. There was no statistical difference in baseline characteristics and prior ischemic heart disease history between groups. In the 26 abnormal perfusion subjects, seven had follow-on coronary angiography in which three were found to have significant stenotic coronary lesions, but only one had intervention performed. There was an unscheduled coronary angiography in the normal perfusion group that yielded normal coronary anatomy. There was no adverse clinical event in both groups. Compared with standard strategy, early outpatient SPECT initiated by EMD physicians followed by cardiac clinic evaluation resulted in 2.9 days of hospitalization or $781.23 saved per patient per EMD visit. EMD-initiated early SPECT studies followed by cardiac clinic evaluation in intermediate-risk acute chest pain syndromes with non-diagnostic ECG and negative serum troponin levels carries excellent diagnostic and therapeutic utility, in addition to being safe and cost-effective.