Cost-effectiveness of a population-based AAA screening program for men over 65 years old in Iran.

BACKGROUND: Screening program tend to recognized patients in their early stage and consequently improve health outcomes. Cost-effectiveness of the abdominal aortic aneurysm (AAA) screening program has been scarcely studied in developing countries. We sought to evaluate the cost-effectiveness of a screening program for the abdominal aortic aneurysm (AAA) in men aged over 65 years in Iran. METHODS: A Markov cohort model with 11 mutually exclusive health statuses was used to evaluate the cost-effectiveness of a population-based AAA screening program compared with a no-screening strategy. Transitions between the health statuses were simulated by using 3-month cycles. Data for disease transition probabilities and quality of life outcomes were obtained from published literature, and costs were calculated based on the price of medical services in Iran and the examination of the patients' medical records. The outcomes were life-years gained, the quality-adjusted life-year (QALY), costs, and the incremental cost-effectiveness ratio (ICER). The analysis was conducted for a lifetime horizon from the payer's perspective. Costs and effects were discounted at an annual rate of 3%. Uncertainty surrounding the model inputs was tested with deterministic and probabilistic sensitivity analyses. RESULTS: The mean incremental cost of the AAA screening strategy compared with the no-screening strategy was $140 and the mean incremental QALY gain was 0.025 QALY, resulting in an ICER of $5566 ($14,656 PPP) per QALY gained. At a willingness-to-pay of 1 gross domestic product (GDP) per capita ($5628) per QALY gained, the probability of the cost-effectiveness of AAA screening was about 50%. However, at a willingness-to-pay of twice the GDP per capita per QALY gained, there was about a 95% probability for the AAA screening program to be cost-effective in Iran. CONCLUSIONS: The results of this study showed that at a willingness-to-pay of 1 GDP per capita per QALY gained, a 1-time AAA screening program for men aged over 65 years could not be cost-effective. Nevertheless, at a willingness-to-pay of twice the GDP per capita per QALY gained, the AAA screening program could be cost-effective in Iran. Further, AAA screening in high-risk groups could be cost-effective at a willingness-to-pay of 1 GDP per capita per QALY gained.

Pocket-sized echocardiography for screening structural heart disease: diagnostic accuracy and cost-effectiveness for population-based studies.

BACKGROUND: The standard transthoracic echocardiography has some limitations in emergent and community-based situations. The emergence of pocket-sized ultrasound has led to influential advancements. METHODS: In this prospective study, in the hospital-based phase, children with suspected structural heart diseases were enrolled. In the school-based phase, healthy children were randomly selected from six schools. All individuals were examined by experienced operators using both the standard and the pocket-sized echocardiography. RESULTS: A total of 73 individuals with a mean age of 9.9 ± 3.2 years in the hospital-based cohort and 143 individuals with a mean age of 12.8 ± 2.9 years in the school-based cohort were examined. The agreements between the standard and the pocket-sized echocardiography were good or excellent for major CHDs in both cohorts (κ statistics > 0.61). Among valvular pathologies, agreements for tricuspid and pulmonary valves' regurgitation were moderate among school-based cohorts (0.56 [95% confidence interval 0.12-1] and 0.6 [95% confidence interval 0.28-0.91], respectively). The agreements for tricuspid and pulmonary valves' regurgitation were excellent (>0.9) among hospital-based population. Other values for valvular findings were good or excellent. The overall sensitivity and specificity were 87.5% (95% confidence interval 47.3-99.7) and 93.8% (95% confidence interval 85-98.3) among the hospital-based individuals, respectively, and those were 88% (95% confidence interval 77.8-94.7) and 68.4% (95% confidence interval 56.7-78.6) among the school-based individuals, respectively. The cost of examination was reduced by approximately 70% for an individual using the pocket-sized device. CONCLUSIONS: When interpreted by experienced operators, the pocket-sized echocardiography can be used as screening tool among school-aged population.

Assessment of subclinical left ventricular dysfunction in patients with chronic mitral regurgitation using torsional parameters described by tissue Doppler imaging.

BACKGROUND: Left ventricular (LV) twist is due to oppositely directed apical and basal rotation and has been proposed as a sensitive marker of LV function. We sought to assess the impact of chronic pure mitral regurgitation (MR) on the torsional mechanics of the left human ventricle using tissue Doppler imaging. METHODS: Nineteen severe MR patients with a normal LV ejection fraction and 16 non-MR controls underwent conventional echocardiography and apical and basal short-axis color Doppler myocardial imaging (CDMI). LV rotation at the apical and basal short-axis levels was calculated from the averaged tangential velocities of the septal and lateral regions, corrected for the LV radius over time. LV twist was defined as the difference in LV rotation between the two levels, and the LV twist and twisting/untwisting rate profiles were analyzed throughout the cardiac cycle. RESULTS: LV twist and LV torsion were significantly lower in the MR group than in the non-MR group (10.38° ± 4.04° vs. 13.95° ± 4.27°; p value = 0.020; and 1.29 ± 0.54 °/cm vs. 1.76 ± 0.56 °/cm; p value = 0.021, respectively), both suggesting incipient LV dysfunction in the MR group. Similarly, the untwisting rate was lower in the MR group (-79.74 ± 35.97 °/s vs.-110.96 ± 34.65 °/s; p value = 0.020), but there was statistically no significant difference in the LV twist rate. CONCLUSION: The evaluation of LV torsional parameters in MR patients with a normal LV ejection fraction suggests the potential role of these sensitive variables in assessing the early signs of ventricular dysfunction in asymptomatic patients.

Assessment of Inter and Intra-atrial Asynchrony in Patients with Systolic Heart Failure Using Velocity Vector Imaging.

BACKGROUND: According to previous studies on the deformation properties of the left atrium, the systolic strain and strain rates represent the atrial reservoir function and the early and late diastolic strain rates show the conduit and booster functions, respectively. OBJECTIVES: We sought to evaluate the intra and interatrial asynchrony using strain/strain rate imaging in systolic heart failure patients. PATIENTS AND METHODS: Twenty five patients with systolic heart failure (LVEF ≤ 40%) were enrolled into the study. Asynchrony quantifications were performed according to the standard deviation of time-to peak (TP-SD) of deformation of three segments manually located along the perimeter of the left atrium free wall, right atrium free wall and interatrial septum, as imaged in an apical four-chamber view. We also calculated classic echocardiography parameters such as LV end-diastolic dimension index, LA volume index, RA area, as well as deceleration time (DT) on transmitral pulsed wave Doppler and E/E' ratio on mitral annular tissue Doppler imaging. RESULTS: In heart failure patients either inter or intra-atrial asynchrony were far more common in comparison with normal subjects (P=0.008 and P=0.007 respectively). CONCLUSIONS: Left ventricular systolic heart failure, may result in inter and intra-atrial asynchrony even in clinically stable patients without significant pulmonary hypertension and diastolic dysfunction.

Quantitative assessment of right atrial function by strain and strain rate imaging in patients with heart failure.

OBJECTIVES: We sought to evaluate the regional longitudinal strain/strain rate profiles in the right atrial wall to quantify right atrial function in systolic heart failure patients. BACKGROUND: According to previous studies on the deformational properties of the left atrium, the systolic strain and strain rates represent the atrial reservoir function and the early and late diastolic strain rates show the conduit and booster functions, respectively. METHODS: Thirty patients with a diagnosis of heart failure (left ventricular ejection fraction < or = 35%) scheduled for right heart catheterization were enrolled. Echocardiography was performed to obtain right atrial deformation indices just before the procedure. The control group consisted of 32 healthy adults matched for age and sex. The deformity indices obtained consisted of the right atrial peak systolic strain (RAS), right atrial peak systolic strain rate (RASSR), right atrial early diastolic strain rate (RAEDSR), and right atrial late diastolic strain rate (RALDSR). RESULTS: The right atrial deformation indices were significantly compromised in the heart failure patients versus the normal subjects (RAS: 68.5 +/- 53.9 vs 189.3 +/- 61.2, P = 0.000; RASSR: 2.9 +/- 1.9 vs. 5.3 +/- 1.5, P = 0.000).There was a significant correlation between the RAS and RASSR and cardiac output (RAS: r = 0.5, P = 0.005; RASSR: r = 0.5, P = 0.003), and cardiac index (RAS: r = 0.6, P = 0.001; RASSR: r = 0.6, P = 0.001). CONCLUSION: In light of our findings, we conclude that a diminished RA function, as assessed by strain imaging, plays a critical role in the pathophysiological process of heart failure patients.

Is the Peak-to-Mean Pressure Gradient Ratio Useful for Assessment of Aortic Valve Prosthesis Obstruction?

BACKGROUND: The evaluation of prosthetic valves is very difficult with two-dimensional transthoracic echocardiography alone. Doppler and color flow imaging as well as transesophageal echocardiography are more reliable to detect prosthetic valve dysfunction. However, Doppler study sometimes tends to be misleading due to the load-depending characteristics of peak and mean pressure gradients. The peak-to-mean pressure decrease ratio is a load-independent measure, which was previously used for the detecting and grading of aortic valve stenosis. We assessed the usefulness of this method for the evaluation of aortic valve prosthesis obstruction. METHODS: One hundred fifty-four patients with aortic valve prostheses were included in this study. Transthoracic and transesophageal echocardiographic examinations were performed in all the patients. Peak velocity and velocity time integral of the aortic valve and left ventricular outflow tract, peak and mean aortic valve pressure gradients, peak-to-mean pressure gradient ratio, and time velocity integral (TVI) index were measured. RESULTS: There was a significant relation between the TVI index (p value < 0.001) and aortic prosthesis obstruction. A TVI index < 0.2 had a sensitivity of 71% and specificity of 100% for the detection of aortic valve prosthesis obstruction. However, no significant relation was found between the peak-to-mean pressure ratio and aortic valve prosthesis obstruction (p value = 0.09). CONCLUSION: Although the peak-to-mean pressure gradient (PG/MG) ratio is a simple, quick, and load-independent method which may be useful for the grading of aortic valve stenosis, it is poorly associated with aortic valve prosthesis obstruction. The TVI index is a useful measure for the detection of aortic prosthesis obstruction.

Doppler echocardiographic assessment of pulmonary prostheses: a comprehensive assessment including velocity time integral ratio and prosthesis effective orifice area.

OBJECTIVE: Few reports have been published on the Doppler-derived echocardiographic data for pulmonary valve prostheses (PVPs). The aim of this study was to provide a comprehensive Doppler echocardiographic assessment of PVPs. METHODS: We studied 40 patients (mean age 24.2) with PVPs: 13 (32.5%) mechanical and 27 (67.5%) bioprosthetic valves. After clinical evaluation, all patients underwent complete, two-dimensional and Doppler studies. RESULTS: In 30 patients with normally functioning PVPs, the mean (SD) peak velocity was 2.33 (0.36) m/s with an average peak pressure gradient of 22.69 (6.7) mm Hg and an average mean pressure gradient of 12.5 (4.1) mm Hg. The mean PVPs velocity time integral (VTI) was 47.49 (12.78) cm with mean right ventricle outflow tract/peak velocity (PV) VTI ratio 0.43 (0.14), mean PVPs effective orifice area was 1.63 (0.36) cm(2). Metallic PVPs had significantly better hemodynamic Doppler study compared with biologic PVPs. In 9 patients with PVP malfunction, average peak PVPs velocity, average peak pressure gradient, mean pressure gradient, PV VTI, PV/left ventricle outflow tract VTI ratio was significantly increased (P < 0.05). CONCLUSION: This study contributes to establishing the normal range for Doppler hemodynamics in various PVPs.