A cost-effectiveness analysis of remote monitoring after pacemaker implantation for bradycardia in Japan.

BACKGROUND: Although remote monitoring (RM) after pacemaker implantation is common, its cost-effectiveness has not been fully investigated. Therefore, we assessed the cost-effectiveness of RM compared with conventional follow-up (CFU) in Japanese patients with pacemakers. METHODS: A Markov model was constructed to analyze costs and quality-adjusted life years after pacemaker implantation. The target population was Japanese patients implanted with a dual-chamber pacemaker for bradycardia. Transition probabilities (e.g. atrial fibrillation, stroke, and device trouble) were obtained from literature and expert sources. Additionally, stroke risk was determined according to anticoagulation and CHADS2 scores. We used a 10-year horizon with sensitivity analyses for significant variables. RESULTS: Compared to CFU, RM was more effective; however, it was also more expensive. When the range of the Japanese willingness-to-pay threshold was considered to be ¥5,000,000, RM was at least cost-neutral relative to the CFU in all elderly patients with pacemakers for bradycardia. The cost-effectiveness of RM relative to CFU could be higher for patients with high CHADS2 scores, especially in patients with a CHADS2 score ≥ 3. Scenario analyses changing the interval between visits to an in-office evaluation in the CFU also demonstrated the same conclusions. In particular, when the interval between office visits was 1 year for the CFU, the RM could be more cost-effective. CONCLUSIONS: This study demonstrated that RM can be a cost-effective option for Japanese patients, especially those with high CHADS2 scores and long-term intervals between office visits.

Combined assessment of subtended myocardial volume and myocardial blood flow for diagnosis of obstructive coronary artery disease using cardiac computed tomography: A feasibility study.

BACKGROUND: This study aimed to evaluate the combined diagnostic performance of coronary artery stenosis-subtended myocardial volume (Vsub) and myocardial blood flow (MBFsub) on computed tomography (CT) for detecting obstructive coronary artery disease (CAD) assessed by invasive coronary angiography (ICA) and fractional flow reserve (FFR). METHODS: Thirty-nine patients who underwent coronary CT angiography (CTA) and stress dynamic myocardial CT perfusion (CTP) prior to ICA were enrolled. Obstructive CAD was defined as severe (≥70%) or moderate (30-69%) stenosis with FFR ≤0.8 on ICA. The Vsub was semi-automatically calculated from coronary CTA data using Voronoi diagram-based myocardial segmentation. The standard CT-MBF based on the 17-segment model was calculated using dynamic stress CTP data and deconvolution analysis. The CT-MBFsub was automatically analyzed by integrating the CT-MBF and Voronoi diagram-based myocardial segmentation analyses. The diagnostic performance of combined CT-MBFsub and Vsub assessment was determined using receiver operating characteristic analysis and compared with standard CT-MBF and CT-MBFsub. RESULTS: Of 117 vessels in 39 patients, 72 vessels were suspected of significant stenosis on CTA and 33 vessels had obstructive CAD on ICA and FFR. The sensitivity and specificity for identifying obstructive CAD were 67% and 82% for standard CT-MBF, 70% and 77% for CT-MBFsub, and 85% and 82% for combined CT-MBFsub and Vsub assessment. The area under the receiver operating characteristic curve of the combined CT-MBFsub and Vsub assessment was significantly higher than those of standard CT-MBF and CT-MBFsub (0.89 vs. 0.75, 0.77; p<0.05). CONCLUSIONS: The Vsub may aid in increasing the diagnostic performance of CT-MBFsub for detecting obstructive CAD.

Intravascular Ultrasound-Derived Virtual Fractional Flow Reserve for the Assessment of Myocardial Ischemia.

BACKGROUND: Fractional flow reserve (FFR) is widely used for the assessment of myocardial ischemia. Intravascular ultrasound (IVUS) is an intracoronary imaging method that provides information about lumen and vessel morphology. Previous studies on the expanded use of IVUS to identify functional ischemia have noted an association between anatomy and physiology, but IVUS-derived minimum lumen area (MLA) has a weak-moderate correlation with myocardial ischemia compared with FFR. We developed a method to calculate FFR using IVUS-derived anatomical information for the assessment of myocardial ischemia. The aims of this study were to investigate the relationship between wire-based FFR and IVUS-derived FFR (IVUS-FFR) and to compare the usefulness of IVUS-FFR and IVUS-derived MLA for functional assessment.Methods and Results:We retrospectively analyzed 50 lesions in 48 patients with coronary stenosis who underwent IVUS and FFR simultaneously. IVUS-FFR was calculated using our original algorithm and fluid dynamics. Mean percent diameter stenosis determined on quantitative coronary angiography and on FFR was 56.4±10.7 and 0.69±0.08, respectively. IVUS-FFR had a stronger linear correlation with FFR (R=0.78, P<0.001; root mean square error, 0.057 FFR units) than with IVUS-derived MLA (R=0.43, P=0.002). CONCLUSIONS: IVUS-FFR may be a more valuable method to identify myocardial ischemia, compared with IVUS-derived MLA.

Intracoronary Optical Coherence Tomography-Derived Virtual Fractional Flow Reserve for the Assessment of Coronary Artery Disease.

Fractional flow reserve (FFR) is widely used for the assessment of myocardial ischemia. Optical coherence tomography (OCT) provides accurate visualization of coronary artery morphology. The aim of this study was to investigate the relation between FFR and OCT-derived FFR. We retrospectively analyzed 31 lesions (25 left anterior descending arteries, 2 left circumflex arteries, and 4 right coronary arteries) in 31 patients with moderate-to-severe coronary stenosis, who underwent OCT and FFR measurements simultaneously. OCT-derived FFR was calculated by the original algorithm, which was calculated using the following equation based on fluid dynamics: ΔP = FV + SV2, where V is the flow velocity, F is the coefficient of pressure loss because of viscous friction (Poiseuille resistance), and S is the coefficient of local pressure loss because of abrupt enhancement (flow separation). Mean values of % diameter stenosis by quantitative coronary angiography and FFR were 55.2 ± 14.0% and 0.70 ± 0.14, respectively. OCT-derived FFR showed a stronger linear correlation with FFR measurements (r = 0.89, p <0.001; root mean square error = 0.062 FFR units) than quantitative coronary angiography % diameter stenosis (r = -0.65, p <0.001), OCT measurements of minimum lumen area (r = 0.68, p <0.001), and % area stenosis (r = -0.70, p <0.001). OCT-derived FFR has the potential to become an alternative method for the assessment of functional myocardial ischemia, and may elucidate the relation between coronary morphology and FFR.

Usefulness of transthoracic Doppler echocardiography for noninvasive assessment of coronary blood flow in a patient with symptomatic myocardial bridging.

Myocardial bridging (MB) is a congenital anomaly characterized by systolic compression of the tunnelled arterial segment. MB may cause myocardial ischaemia due to abnormal coronary blood flow. We report a case of MB in which transthoracic Doppler echocardiography was used to evaluate the long-term effect of beta-blocker therapy on abnormal coronary blood flow. In this case, beta-blocker therapy with bisoprolol (5.0 mg/day) for 1 month eliminated the patient's symptoms and normalized coronary blood flow through the tunnelled arterial segment.

Assessment of flow velocity in a bypass graft of the gastroepiploic artery by contrast-enhanced transabdominal Doppler echocardiography: a case report.

An 81-year-old man with effort angina pectoris underwent coronary artery bypass grafting operation using the bilateral internal thoracic arteries and the right gastroepiploic artery (GEA). Angiography after operation showed that the bilateral internal thoracic arteries were patent. Abdominal angiography showed severe ostial stenosis in the celiac trunk. The GEA was not opacified by the celiac trunk but by the superior mesenteric artery, by collaterals. GEA flow could be detected from the epigastric lesion by contrast-enhanced Doppler echocardiography, and moreover, the flow velocity reserve of the graft was 2.4. This case suggests that the GEA graft can provide sufficient blood flow to the coronary artery despite ostial stenosis of the celiac trunk.

Assessment of intermediate stenosis in the left anterior descending coronary artery with contrast-enhanced transthoracic Doppler echocardiography.

BACKGROUND: Visual or quantitative assessment of coronary angiography may not exactly predict the physiological significance of intermediate (40-70%) coronary stenosis. Coronary flow reserve is a well-established marker of the functional significance of coronary stenosis. OBJECTIVES: The aim of this study was to compare the coronary flow velocity reserve (CFVR) using contrast-enhanced transthoracic Doppler echocardiography (CE-TTDE) with thallium-201 imaging in assessment of intermediate lesions in the left anterior descending coronary artery (LAD). METHODS: A consecutive series of 50 patients with intermediate stenosis in the LAD underwent pharmacological stress thallium-201 imaging and CFVR measured by CE-TTDE. RESULTS: CFVR could be measured in 49 of 50 patients by the present method. A CFVR <2.0 predicted the presence of a stress thallium defect in 12 of 14 patients (agreement=90%, kappa=0.76, P < 0.001). The sensitivity and specificity of CFVR for stress thallium-201 results were 86 and 91%, respectively. In contrast, significant stenosis (>50% by diameter) showed fair agreement for stress thallium defects (agreement=59%, kappa=0.28, P < 0.05). CONCLUSIONS: In the evaluation of intermediate lesions in the LAD, CFVR as assessed by CE-TTDE could accurately predict the presence of ischemia on stress thallium imaging, whereas angiographic stenosis did not yield reliable results.