Makoto Iwama

Left atrial function assessed by speckle tracking echocardiography as a predictor of new-onset non-valvular atrial fibrillation: results from a prospective study in 580 adults

AIMS The aim of this prospective study was to evaluate left atrial (LA) function for the prediction of increased risk of new-onset non-valvular atrial fibrillation (AF). Risk stratification for new-onset AF based on LA remodelling may have a major public health impact. Although left atrial volume (LAV) or LA dimension have been proposed as predictors of AF, other predictive parameters of LA function have not yet been fully examined. METHODS AND RESULTS LA emptying function (EF), strain rate (SR), and LAV were evaluated in the apical four-chamber view by speckle tracking echocardiography in 580 consecutive adults (age 64 ± 17, 303 men) without a history of atrial arrhythmias. During a follow-up period of 28 months, 32 subjects (age 73 ± 9, 18 men) developed electrocardiographically confirmed AF. Subjects with new-onset AF had lower LA active EF (16 ± 5 vs. 28 ± 8%, P< 0.001) and lower LA SR at atrial contraction (-0.9 ± 0.2 vs. -1.4 ± 0.5 S(-1), P< 0.001), but larger maximum LAV index (59 ± 12 vs. 46 ± 16 mL/m(2), P< 0.001) compared with non-AF subjects at baseline. In multivariate logistic regression analysis, LA active EF was the only independent predictor of new-onset AF. Using an LA active EF cut-off of ≤20%, the sensitivity and specificity for new-onset AF based on receiver operator characteristic curve analysis were 88 and 81%, respectively (area under the curve: 0.92). CONCLUSION Reduced LA active EF (booster pump function) assessed by speckle tracking echocardiography independently predicts the risk of new-onset AF, suggesting a stronger association between LA functional remodelling and AF than between LA size and AF.

Left atrial global and regional function in patients with paroxysmal atrial fibrillation has already been impaired before enlargement of left atrium: velocity vector imaging echocardiography study.

AIMS Left atrial volume (LAV) has been proposed as a predictor of atrial fibrillation (AF) and LA function has been investigated by velocity vector imaging (VVI) echocardiography. The aim of this study was to determine whether LA function was associated with the existence of AF. METHODS AND RESULTS We examined emptying function (EF) as a global function and strain rate (SR) as a regional function of LA function during three phases of the cardiac cycle (reservoir, conduit, and booster pump phase). The parameters were measured (apical four-chamber view) by VVI in 302 subjects [126 sinus rhythm, 91 paroxysmal AF (PAF), and 85 chronic AF]. Global and regional LA function were significantly lower in PAF patients during sinus rhythm (LA total EF: 35 ± 8%; SR at atrial contraction: -0.8 ± 0.3s(-1)) and much lower in chronic AF patients (LA total EF 22 ± 8%) than in subjects with sinus rhythm (LA total EF: 47 ± 7%; SR at atrial contraction: -1.4 ± 0.4s(-1)). In multivariate logistic regression analysis, LA active EF and SR at atrial contraction were independent features of PAF. CONCLUSION LA function, particularly LA active relaxation and contraction, was lower in PAF patients than in subjects with sinus rhythm, regardless of LA size and age. LA functional impairment was observed regardless of hypertension before LA enlargement in patients with PAF. Reduced LA function, as assessed by VVI, is an important feature of AF as well as LA structure.

Prospective randomized trial comparing a nitinol self-expanding coronary stent with low-pressure dilatation and a high-pressure balloon expandable bare metal stent

The recent SCORES trial demonstrated that lower dilatation pressures seen with self-expanding (SE) stents may be associated with lower rates of target lesion revascularization (TLR). To determine whether SE stents with low-pressure dilatation are as safe and effective as balloon expandable (BE) stents. We randomly assigned 254 patients with 279 coronary lesions to groups receiving either SE with low-pressure dilatation <12 atm (n = 143) or conventional BE stents (n = 136). Thereafter, acute results and long-term outcomes were compared. Baseline patient and angiographic characteristics were similar in two groups. The incidence of procedural complications, such as slow flow, side branch occlusion, and edge dissection were significantly lower in the SE group than in the BE group (overall: SE, 17; BE, 35; P < 0.01), and the occurrence of myocardial infarction tended to be lower in SE than in BE (SE, 1; BE, 4; not significant). Although acute gain was significantly smaller with SE than BE (SE, 2.21 ± 0.65 mm; BE, 2.42 ± 0.62; P < 0.01), probably due to gradual expansion of the SE stent, nearly identical minimum luminal diameters on follow-up angiography (SE, 2.14 ± 0.92 mm vs. BE, 2.22 ± 0.93; not significant) and similar angiographic restenosis (SE, 18.1% vs. BE, 20.5%). and TLR rates (SE, 16.1% vs. BE, 14.0%) were apparent. This prospective randomized trial demonstrates that SE stents with low-pressure dilatation is safe and effective strategy for treating coronary arterial stenosis.

Left atrial appendage emptying fraction assessed by a feature-tracking echocardiographic method is a determinant of thrombus in patients with nonvalvular atrial fibrillation

BACKGROUND Left atrial appendage (LAA) thrombus increases the risk of thromboembolism in atrial fibrillation (AF), and LAA contractile function like emptying fraction (EF) should have physiological importance in thrombus formation. The aim of this study was to validate a velocity vector imaging (VVI) method for quantification of the LAA function and to elucidate echocardiographic parameters that are related to the presence of LAA thrombus in patients with nonvalvular AF. METHODS We measured left atrial (LA) dimension and LAEF by VVI using transthoracic echocardiography, and LAA emptying velocity, spontaneous echo contrast (SEC), and LAAEF by VVI using transesophageal echocardiography (TEE) in 142 consecutive patients with nonvalvular AF. The patients were divided into two groups according to the presence (n=38) or absence (n=104) of LAA thrombus. RESULTS There was a good correlation between the VVI method and manual-tracing method for LAAEF and LAEF of patients with AF (r=0.97, r=0.96, respectively, p<0.001). LAAEF in AF with thrombus was significantly reduced compared with AF without thrombus (16.9±3.1% and 29.0±9.7%, p<0.001). In multivariate logistic regression analysis, LAAEF, SEC, and prior stroke were independent determinants of LAA thrombus. Using 20% of LAAEF as a cutoff value, the sensitivity was 92% and specificity was 88% for LAA thrombus. CONCLUSION The VVI method was reliable in the measurement of LAAEF and LAEF compared with the manual-tracing method. LAAEF assessed by the VVI method using TEE was related to the presence of LAA thrombus.

Motion of left atrial appendage as a determinant of thrombus formation in patients with a low CHADS2 score receiving warfarin for persistent nonvalvular atrial fibrillation

BackgroundThe aim of this study was to define the independent determinants of left atrial appendage (LAA) thrombus among various echocardiographic parameters measured by Velocity Vector Imaging (VVI) in patients with nonvalvular atrial fibrillation (AF) receiving warfarin, particularly in patients with a low CHADS2 score.MethodsLAA emptying fraction (EF) and LAA peak longitudinal strain were measured by VVI using transesophageal echocardiography in 260 consecutive patients with nonvalvular persistent AF receiving warfarin. The patients were divided into two groups according to the presence (n=43) or absence (n=217) of LAA thrombus. Moreover, the patients within each group were further divided into subgroups according to a CHADS2 score ≤1.ResultsMultivariate logistic regression analysis showed that LAAEF was an independent determinant of LAA thrombus in the subgroup of 140 with a low CHADS2 score. Receiver operating characteristics curve analysis showed that an LAAEF of 21% was the optimal cutoff value for predicting LAA thrombus.ConclusionsLAA thrombus formation depended on LAA contractility. AF patients with reduced LAA contractile fraction (LAAEF ≤21%) require strong anticoagulant therapy to avoid thromboembolic events regardless of a low CHADS2 score (≤1).

A novel ultrasound predictor of pulmonary capillary wedge pressure assessed by the combination of left atrial volume and function: A speckle tracking echocardiography study

BACKGROUND We hypothesized that a development of a novel index based on the combination of left atrial volume (LAV) and left atrial (LA) function evaluated by the time-LA volume curve using speckle tracking echocardiography (STE) would be accurate and useful to estimate pulmonary capillary wedge pressure (PCWP). Our goal was to develop a novel index of PCWP based on a combination of LAV and LA function using STE. METHODS A cross-validation study was performed with the patients divided into a training study to define the novel index (n=50) and a testing study to validate the index (n=196). PCWP was measured by right heart catheterization, and phasic LAV and emptying function (EF) were measured by STE. RESULTS Simple linear regression analysis in the training study revealed that the novel index that best estimated PCWP was the kinetics-tracking index [KT index=log10 (active LAEF/minimum LAV index)]. Multiple regression analysis revealed that the KT index was the most reliable predictor of PCWP. It had the strongest correlation with PCWP (r=-0.86, p<0.001) among all echocardiographic parameters. In the testing study, PCWP estimated by the KT index was also strongly correlated with measured PCWP (r=0.92, p<0.001). These correlations were also strong in the patients with reduced left ventricular ejection fraction (<50%), chronic heart failure, and chronic atrial fibrillation (r=0.92, r=0.91, r=0.79, p<0.001, respectively). CONCLUSIONS A novel index (KT index) using a combination of LAV and LA function was a powerful and useful predictor of PCWP and may be valuable in routine clinical practice.

Relation between functional stenosis and tissue characterization of intermediate coronary plaques in patients with stable coronary heart disease

BACKGROUND Tissue characteristics of coronary plaques can be evaluated using integrated backscatter intravascular ultrasound (IB-IVUS), while fractional flow reserve (FFRmyo) is an index of functional coronary stenosis. We assessed the relation between functional stenosis and the characteristics of plaque tissue using FFRmyo and IB-IVUS. METHODS AND RESULTS A total of 17 lesions with 75%-stenosis assessed visually by coronary angiography from 17 stable angina patients (64.2+/-9.1 years old, 11 males) were studied. IB-IVUS was evaluated in the most stenotic cross-sectional area. Using commercially available software, coronary plaques were assessed for calcification (CA), fibrosis (F), and lipid pool (LP). Lesions were localized in the left anterior descending artery in 11 patients, the left circumflex in 3, and the right coronary artery in 3. On quantitative coronary angiography, the percent diameter stenosis (%DS) was 60.5+/-7.3%. Plaque burden was 71.4+/-9.1%, FFRmyo was 0.74+/-0.13. The tissue component of the plaques was: CA(%), 3.0+/-2.4%; F(%), 60.5+/-9.6%; LP(%), 37.2+/-11.0%. Significant correlation was not observed between %DS or plaque burden and FFRmyo, structural stenosis and plaque characterization, nor between CA(%) and FFRmyo. There was a positive correlation between F(%) and FFRmyo (r=0.62, p<0.01) and a negative correlation between LP(%) and FFRmyo (r=-0.52, p<0.05). CONCLUSION Our findings indicate that the tissue characteristics of coronary plaques in intermediate lesion affect functional stenosis.

Impact of tissue characteristics on luminal narrowing of mild angiographic coronary stenosis: assessment of integrated backscatter intravascular ultrasound.

Integrated backscatter intravascular ultrasound (IB-IVUS) is a useful method for analyzing coronary plaque tissue. We evaluated whether tissue composition determined using IB-IVUS is associated with the progression of stenosis in coronary angiography. Sixty-three nontarget coronary lesions in 63 patients with stable angina were evaluated using conventional IVUS and IB-IVUS. IB-IVUS images were analyzed at 1-mm intervals for a length of 10 mm. After calculating the relative areas of the tissue components using the IB-IVUS system, fibrous volume (FV) and lipid volume (LV) were calculated through integration of the slices, after which percentages of per-plaque volume (%FV/PV, %LV/PV) and per-vessel volume (%FV/VV, %LV/VV) were calculated. Progression of coronary stenosis was interpreted from the increase in percent diameter stenosis (%DS) from baseline to the follow-up period (6–9 months) using quantitative coronary angiography. %DS was 24.1 ± 12.8 % at baseline and 23.2 ± 13.7 % at follow-up. Using IB-IVUS, LV was 31.7 ± 10.5 mm3, and %LV/PV and %LV/VV were 45.6 ± 10.3 % and 20.2 ± 6.0 %, respectively. FV, %FV/PV, and %FV/VV were 35.5 ± 12.1 mm3, 52.1 ± 9.5 %, and 23.4 ± 7.1 %, respectively. The change in %DS was −0.88 ± 7.25 % and correlated closely with %LV/VV (r = 0.27, P = 0.03) on simple regression. Multivariate regression after adjustment for potentially confounding risk factors showed %LV/VV to be correlated independently with changes in %DS (r = 0.42, P = 0.02). Logistic regression analysis after adjusting for confounding coronary risk factors showed LV (odds ratio 1.08; 95 % confidence interval 1.01–1.16; P = 0.03) and %LV/VV (odds ratio 1.13; 95 % confidence interval 1.01–1.28; P = 0.03) to be independent predictors of the progression of angiographic coronary stenosis. Our findings suggest that angiographic luminal narrowing of the coronary artery is likely associated with tissue characteristics. IB-IVUS may provide information about the natural progression of luminal narrowing in coronary stenosis.

Over 10 years clinical outcomes in patients with mitral stenosis with unilateral commissural calcification treated with catheter balloon commissurotomy : Single-center experience

OBJECTIVES Treatment of mitral valve stenosis with catheter balloon commissurotomy (CBC) yields acceptable immediate results even when one commissure shows calcification. However, the long-term outcomes in such cases remain unclear. METHODS We examined the immediate and long-term (mean: 11+/-5 years) outcomes of 57 patients who underwent 58 CBC procedures. Patients were classified into group A (no commissural calcification, n=44) or group B (unilateral commissural calcification, n=13). From the appearance of the mitral valve just after CBC, commissurotomy was judged to be bilateral, incomplete, or excessive. End points were death, recurrence of congestive heart failure necessitating hospitalization, embolism, repeat CBC, or mitral valve replacement. RESULTS There were significant numbers of unfavorable mitral valve morphologies evaluated according to Sellors classification, estimated by echocardiograms; Sellors class I: 20 patients in group A vs. none in group B (p<0.05). Class II: 24 in group A vs. 10 in group B. and class III: none in group A vs. 3 in group B (p<0.05). CBC increased the mitral valve area (Gorin formula) from 1.3+/-0.3 to 2.1+/-0.5 cm2 in patients in group A and from 1.1+/-0.2 to 1.8+/-0.4 cm2 in those in group B (p=n.s.). Among the latter, there were significantly more excessive commissurotomies than in group A and no bilateral commissurotomy. The overall or event-free survival rate during the follow-up of group B showed a lower tendency than in group A (overall: group A: 86.2% vs. group B: 84.6%, p, n.s. event-free: 56.8% vs. 46.2%, respectively, p=n.s.). Univariate predictors of all events in group B included post-CBC pulmonary arterial pressure, and the pattern of commissurotomy after CBC (p<0.05). Excessive commissurotomy increased clinical events some years later, after the procedure. CONCLUSIONS In this study, involving a small number of subjects, long-term outcomes of patients with unilateral commissural calcification receiving CBC showed no significant difference as compared to those with commissural calcification absence. However, it is necessary to perform careful follow-up of CBC patients with unilateral commissural calcium.

Myocardial perfusion during transient slow-flow in the patient with old vein graft intervention: assessment by serial measurement of pressure-derived fractional flow reserve and thermodilution-derived coronary flow reserve.

A patient with distal slow‐flow after stenting in the old vein graft intervention was reported. This case is a first in whom guidewire‐based serial measurement of pressure‐derived fractional flow reserve (FFRmyo) and thermodilution‐based coronary flow reserve (CFRthermo) clearly demonstrated the serial change of microvascular circulation. During slow‐flow, CFRthermo remained in low value despite significant improvement of FFRmyo from 0.61 to 0.90. After thrombus aspiration and nicorandil injection, coronary flow reestablished immediately. CFRthermo improved significantly from 1.3 during slow‐flow to 3.6 after restoration of flow. Catheter Cardiovasc Interv 2003;60:392–398.