Feasibility of left atrial strain assessment using cardiac computed tomography in patients with paroxysmal atrial fibrillation.

PURPOSE: To evaluate the feasibility of left atrial strain (LAS) assessment using cardiac computed tomography (CT) in patients with paroxysmal atrial fibrillation (PAF). METHODS: This retrospective single-center study included 98 patients with PAF who underwent cardiac CT and echocardiography before the first catheter ablation. LAS was analyzed using cardiac CT (CT-LAS) and speckle-tracking echocardiography (STE; STE-LAS). LA reservoir (LASr), conduit (LASc), and pump strain (LASp) were calculated by averaging LAS measured in 4- and 2-chamber views. The results were compared using Pearson's correlation coefficients, paired t-tests, and Bland-Altman analysis. Intraclass correlation coefficients (ICCs) were used to evaluate reproducibility. RESULTS: CT-LAS could be analyzed in all patients, while STE-LAS could be analyzed in 53 (54%) patients. LASr, LASc, and LASp showed significant correlations between CT- and STE-LAS: LASr, r = 0.68, p < 0.001; LASc, r = 0.47, p < 0.001; LASp, r = 0.67, p < 0.001. LASr, LASc, and LASp of CT- and STE-LAS were 23.7 ± 6.0% and 22.1 ± 6.7%, 11.1 ± 3.6% and 11.1 ± 4.1%, and 12.6 ± 4.6% and 11.0 ± 4.1%, respectively. LASr and LASp were significantly higher in CT-LAS than that in STE-LAS (p = 0.023 for LASr and p = 0.001 for LASp). CT-LAS showed excellent reproducibility. The intra- and interobserver ICCs were 0.96 to 0.99 and 0.89 to 0.90, respectively. CONCLUSION: CT-LAS was successfully analyzed in more patients than STE-LAS and was highly reproducible. The findings suggest that CT-LAS is feasible for patients with PAF.

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.

Left atrial strain assessment using cardiac computed tomography in patients with hypertrophic cardiomyopathy.

PURPOSE: To evaluate left atrial (LA) function in patients with hypertrophic cardiomyopathy (HCM) by LA strain assessment using cardiac computed tomography (CT-derived LA strain). MATERIALS AND METHODS: This was a retrospective study of 34 patients with HCM and 31 non-HCM patients who underwent cardiac computed tomography (CT) using retrospective electrocardiogram-gated mode. CT images were reconstructed every 5% (0-95%) of the RR intervals. CT-derived LA strain (reservoir [LASr], conduit [LASc], and booster pump strain [LASp]) were semi-automatically analyzed using a dedicated workstation. We also measured the left atrial volume index (LAVI) and left ventricular longitudinal strain (LVLS) for the left atrial and ventricular functional parameters to assess the relationship with CT-derived LA strain. RESULTS: CT-derived LA strain significantly correlated with LAVI: r = - 0.69, p < 0.001 for LASr; r = - 0.70, p < 0.001 for LASp; and r = - 0.35, p = 0.004 for LASc. CT-derived LA strain also significantly correlated with LVLS: r = - 0.62, p < 0.001 for LASr; r = - 0.67, p < 0.001 for LASc; and r = - 0.42, p = 0.013 for LASp. CT-derived LA strain in patients with HCM was significantly lower than that in non-HCM patients: LASr (20.8 ± 7.6 vs. 31.7 ± 6.1%, p < 0.001); LASc (7.9 ± 3.4 vs. 14.2 ± 5.3%, p < 0.001); and LASp (12.8 ± 5.7 vs. 17.6 ± 4.3%, p < 0.001). Additionally, CT-derived LA strain showed high reproducibility; inter-observer correlation coefficients were 0.94, 0.90, and 0.89 for LASr, LASc, and LASp, respectively. CONCLUSION: CT-derived LA strain is feasible for quantitative assessment of left atrial function in patients with HCM.

Echocardiographic Assessment of Atrial Function: From Basic Mechanics to Specific Cardiac Diseases.

The left and right atria serve as buffer chambers to control the flow of venous blood for ventricular filling. If an atrium is absent, blood does not flow effectively into the ventricle, leading to venous blood retention and low cardiac output. The importance of atrial function has become increasingly recognized, because left atrial (LA) function contributes to cardiac performance, and loss of LA function is associated with heart failure. LA volume change has been used for LA function assessment in experimental and clinical studies. In conjunction with LA pressure, the LA pressure-volume relationship provides a better understanding of LA mechanics. LA strain measurement by speckle tracking echocardiography was introduced to evaluate three components of LA function as a (booster) pump, reservoir and conduit. Furthermore, increasing evidence supports the theory that LA reservoir strain has prognostic utility in various cardiac diseases. In this review, we summarize LA contribution to maintain cardiac performance by evaluating LA function with echocardiography according to our experiences and previous reports. Furthermore, we discuss LA dysfunction in challenging cardiac diseases of cardiac amyloidosis and adult congenital heart disease.

Usefulness of intravascular ultrasound assessment after development of the slow flow phenomenon during percutaneous coronary intervention.

The slow flow phenomenon is a critical complication during percutaneous coronary intervention (PCI) that leads to poor outcomes. We aimed to evaluate the mechanisms underlying the slow flow phenomenon using intravascular ultrasound (IVUS). We retrospectively analyzed IVUS data from 62 lesions in 58 consecutive patients who experienced the slow flow phenomenon during PCI. IVUS was performed immediately after the development of the slow flow phenomenon to assess its cause. No IVUS-based evidence of mechanical obstruction was categorized as distal embolization. Distal embolization was observed in 46 lesions (74%). The slow flow phenomenon occurred in all these lesions after stent implantation. In addition to distal embolization, three different mechanisms underlying the induction of the slow flow phenomenon due to mechanical obstructions (16 lesions, 26%) were detected on IVUS, namely, medial dissection/hematoma (6 lesions), intimal flap (6 lesions), and thrombus obstruction (4 lesions). Most mechanical obstructions (13 lesions, 81%) could not be identified by angiography alone. In 15/16 lesions (94%) with mechanical obstruction, deteriorated flow improved immediately after balloon dilatation or bail-out stent implantation, although intracoronary vasodilator administration could not reestablish coronary flow. The frequency of mechanical obstruction as the cause of the slow flow phenomenon was relatively high. Given the difficulty in angiographical differentiation, IVUS-guided management of slow flow may be a useful strategy.

Cost-Effectiveness of long-term tolvaptan administration for chronic heart failure treatment in Japan.

BACKGROUND: Tolvaptan (TLV) is effective for acute heart failure (HF) with congestion, but its long-term administration in patients with chronic HF (CHF) remains controversial. Moreover, the cost-effectiveness of TLV for CHF treatment has not yet been investigated. Thus, we sought to validate the cost-effectiveness of TLV for CHF treatment in Japan. METHODS: A Markov model was developed to compare total costs, quality-adjusted life years (QALYs), and incremental cost-effectiveness ratio (ICER) between long-term TLV strategy and the standard strategy using furosemide for CHF. The target population included 75-year-old patients with CHF. The effectiveness of the TLV strategy for CHF treatment was determined based on a systematic review and meta-analysis. We used a 10-year horizon, with sensitivity analyses for significant variables and a scenario analysis for patients with CHF receiving high-dose furosemide (≥60 mg per day). RESULTS: In the base case analysis, the total cost of the long-term TLV strategy was higher than that of the standard strategy (¥3,243,779 vs. ¥1,179,964). The total QALYs of the long-term TLV strategy were lower than those of the standard strategy (4.52 vs 4.59). Thus, a standard TLV prescription for CHF treatment has no clinical or economic benefit. In the scenario analysis (i.e. in patients with CHF receiving high-dose furosemide), the long-term TLV strategy was more effective (total QALYs, 5.10 vs. 4.41) but more expensive (total costs, ¥3,540,558 vs. ¥1,272,208) than the standard strategy. The ICER of the TLV strategy against the standard strategy (¥3,289,579/QALY) was below the willingness-to-pay of ¥5,000,000, which suggests that the long-term TLV strategy is cost-effective relative to the standard strategy in patients with CHF receiving high-dose furosemide. CONCLUSIONS: Long-term TLV administration did not provide a clear benefit for all patients with CHF. However, this treatment strategy may be a cost-effective therapeutic option for patients who require high-dose furosemide.

Semiquantitative assessment of the relative apical sparing pattern of longitudinal strain for cardiac amyloidosis identification.

BACKGROUNDS: The relative apical sparing pattern (RASP) of left ventricular (LV) longitudinal strain (LS) is frequently associated with cardiac amyloidosis (CA). However, the visual assessment of RASP is inconsistent, and the quantitative assessment of RASP is time-consuming. This study aimed to compare assessments of RASP for the identification of CA with conventional assessments and investigate their reproducibility and relevance on the assessments. METHODS: Forty patients with biopsy-proven CA were compared with 80 hypertrophied patients matched for mean LV wall thickness. We compared the discriminative abilities of three assessments of RASP to identify CA (visual, quantitative, and semiquantitative). Nine patterns of semiquantitative RASP were investigated; finally, it was defined as "reduction of LS" (≥ -10%) in ≥5 (of 6) basal segments, relative to "preserved LS" (< -15%) in at least one apical segment. RESULTS: The concordance between the two observers for visual RASP was modest (κ = 0.65). On the other hand, the consistency for semiquantitative RASP was perfect (κ = 1.00). The discriminative ability of semiquantitative RASP (area under the curve [AUC]  = 0.74) was significantly better than that of visual RASP (AUC = 0.65) and equivalent to that of binary quantitative RASP. CONCLUSION: Semiquantitative RASP assessment is reproducible and accurately discriminates CA. This simple assessment may help readily refine the risk stratification of patients with diffuse LV hypertrophy.

Prognostic assessment of relative apical sparing pattern of longitudinal strain for severe aortic valve stenosis.

BACKGROUNDS: The relative apical sparing pattern (RASP) of left ventricular (LV) longitudinal strain (LS) is frequently associated with cardiac amyloidosis. Elderly patients with aortic valve stenosis (AS) complicated by transthyretin amyloid cardiomyopathy have poor prognosis. Furthermore, deteriorated basal LS in AS patients has been reported to be associated with adverse outcome. We investigated the association between RASP and outcomes in patients with severe AS. METHODS: We retrospectively studied 156 consecutive patients with severe AS and preserved LV ejection fraction. RASP was assessed by both of semi-quantitative (sRASP) and quantitative (qRASP) methods. sRASP was defined as a deterioration of LS (≥-10%) in ≥ 5 (of 6) basal segments, relative to preserved LS (<-15%) in at least 1 apical segment. qRASP was calculated using the following formula: average apical LS/(average basal LS + average mid-ventricle LS); qRASP ≥ 1 was defined as positive. Patients were followed up to determine outcomes, which included sudden cardiac death or unexpected admission due to heart failure, over a median of 1.9 years. RESULTS: sRASP and qRASP were assessed in all patients, but 24 and 42 patients fulfilled the criteria for sRASP and qRASP, respectively. Both assessments were significantly associated with outcomes (n = 44; 28%). Furthermore, sRASP was significantly associated with outcome after adjusting for EuroSCORE, NYHA ≥ II, or global longitudinal strain. A model based on these covariates for predicting outcomes significantly improved by adding sRASP. CONCLUSION: RASP is observed in some patients with severe AS and provides additive prognostic information over conventional parameters.

Assessment of Left Atrial Work During Acute Coronary Occlusion.

Left atrial (LA) work can be measured through speckle tracking echocardiography by calculating LA pressure-strain loop area, which includes two distinct phases of active contraction/relaxation (A-work) and passive dilation/emptying (V-work). Echocardiographic and hemodynamic data were acquired at baseline and during occlusions of left anterior descending (LAD: n = 7) and left circumflex (LCx: n = 9) coronary arteries in dogs. Left ventricular (LV) circumferential strain was decreased and mean LA pressure was increased in both occlusions. Doppler-derived stroke volume was maintained during LAD occlusion, but it decreased during LCx occlusion. A-work increased during LAD occlusion, but it did not change during LCx occlusion. V-work decreased during LCx occlusion more than during LAD occlusion. The compensatory mechanism of LA function was limited during LCx occlusion, but this occurred during LAD occlusion. This study provided insight into a role of LA function in variable hemodynamic consequences in acute myocardial infarction.

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.

The Speckle Tracking Imaging for the Assessment of Cardiac Resynchronization Therapy (START) study.

BACKGROUND: We sought to identify the feasibility of speckle tracking echocardiography (STE) to predict cardiac resynchronization therapy (CRT) responders in a prospective multicenter study. METHODS AND RESULTS: Patients who were newly implanted with a CRT device were enrolled. Time (T) from QRS to maximum peak radial and circumferential strain (CS) in 6 segments on the left ventricular (LV) short-axis plane, and to the maximum peak of longitudinal strain in 18 segments on 3 apical LV planes was measured (Tmax). In segments with multiple peaks on the time-strain curves, time to the first peak (Tfirst) was also assessed. Difference in T between the earliest and latest segment and standard deviation (SD) of T in each strain component were assessed. CRT responders were defined as having LV end-systolic volume reduction >15% at 6 months after CRT. Clinical outcomes were assessed with a composite endpoint of death from cardiac causes or unplanned hospitalization for heart failure. Among 180 patients, 109 patients were identified as responders. Tfirst-SD of CS >116 ms was selected as the best independent predictor of CRT responders (P<0.001, hazard ratio=9.83, 95% confidence interval 3.78-25.6). In addition, Tfirst-SD of CS was associated with the clinical endpoints. CONCLUSIONS: This prospective multicenter study revealed the high feasibility of dyssynchrony assessment by STE, which may improve the ability to predict CRT responders.

Qualitative and quantitative assessment of adenosine triphosphate stress whole-heart dynamic myocardial perfusion imaging using 256-slice computed tomography.

BACKGROUND: The aim of this study was to investigate the correlation of the qualitative transmural extent of hypoperfusion areas (HPA) using stress dynamic whole-heart computed tomography perfusion (CTP) imaging by 256-slice CT with CTP-derived myocardial blood flow (MBF) for the estimation of the severity of coronary artery stenosis. METHODS AND RESULTS: Eleven patients underwent adenosine triphosphate (0.16 mg/kg/min, 5 min) stress dynamic CTP by 256-slice CT (coverage: 8 cm, 0.27 s/rotation), and 9 of the 11 patients underwent coronary angiography (CAG). Stress dynamic CTP (whole-heart datasets over 30 consecutive heart beats in systole without spatial and temporal gaps) was acquired with prospective ECG gating (effective radiation dose: 10.4 mSv). The extent of HPAs was visually graded using a 3-point score (normal, subendocardial, transmural). MBF (ml/100g/min) was measured by deconvolution. Differences in MBF (mean ± standard error) according to HPA and CAG results were evaluated. In 27 regions (3 major coronary territories in 9 patients), 11 coronary stenoses (> 50% reduction in diameter) were observed. In 353 myocardial segments, HPA was significantly related to MBF (P < 0.05; normal 295 ± 94; subendocardial 186 ± 67; and transmural 80 ± 53). Coronary territory analysis revealed a significant relationship between coronary stenosis severity and MBF (P < 0.05; non-significant stenosis [< 50%], 284 ± 97; moderate stenosis [50-70%], 184 ± 74; and severe stenosis [> 70%], 119 ± 69). CONCLUSION: The qualitative transmural extent of HPA using stress whole-heart dynamic CTP imaging by 256-slice CT exhibits a good correlation with quantitative CTP-derived MBF and may aid in assessing the hemodynamic significance of coronary artery disease.

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.