Michihiro Suwa

Iodine-123 metaiodobenzylguanidine myocardial scintigraphy for prediction of response to β-blocker therapy in patients with dilated cardiomyopathy

This study was performed to evaluate whether iodine-123 metaiodobenzylguanidine (MIBG) myocardial scintigraphy could predict the response to beta-blocker therapy in patients with nonischemic dilated cardiomyopathy (DCM). Beta-Blocker therapy is effective in some patients with DCM. MIBG myocardial scintigraphy has also been suggested to be useful in evaluating the severity of myocardial damage in DCM. However, no data exist on whether MIBG imaging can be used to predict which patients with DCM will respond to beta-blocker therapy. We prospectively evaluated whether MIBG myocardial imaging was useful in predicting responses to beta-blocker therapy in patients with DCM. MIBG imaging was performed in 45 patients with DCM (35 men, 10 women, aged 13 to 68 years) before the start of bisoprolol. The heart to mediastinum (H/M) MIBG uptake ratio was evaluated on initial and delayed images, and the percent washout rate of myocardial MIBG was also obtained from these data. Of the 45 patients, 30 (67%) responded to beta-blocker therapy, whereas 2 were resistant and 13 showed progression of heart failure or died of heart failure. By logistic regression analysis, the H/M uptake ratio on delayed images was seen to be a good predictor of the response to beta-blocker therapy with a threshold of 1.7 (sensitivity = 91%, specificity = 92%, accuracy = 91%, positive and negative predictive value = 97% and 80%, respectively). These results indicate that an H/M ratio > 1.7 on the delayed MIBG myocardial scintigraphic images provides a useful indication of whether patients with DCM will respond to beta-blocker therapy.

Natural History and Left Ventricular Response in Chronic Aortic Regurgitation

This study was aimed at clarifying the natural history and left ventricular response in aortic regurgitation using M-mode echocardiography. We analyzed the history and echocardiographic data on 94 patients, who were divided into 4 stages according to symptoms. The duration of the asymptomatic period, which represents pure volume overload, is long, and the period of minimal symptoms, combined volume and pressure overload, is relatively short. Patients with overt heart failure due to impaired contractility can survive longer than is usually believed, and the factor that predicted the onset of heart failure was a decrease in fractional shortening > 3.8 percentage points.

Improvement in left ventricular diastolic function during intravenous and oral diltiazem therapy in patients with hypertrophic cardiomyopathy: An echocardiographic study

M-mode echocardiography was used to evaluate the acute effect of intravenously administered diltiazem, 10 mg, and the chronic effects of oral diltiazem, 180 mg/day, and propranolol, 60 to 120 mg/day, administered for 2 weeks on left ventricular (LV) systolic and diastolic function in 13 patients with hypertrophic cardiomyopathy. Intravenous injection of diltiazem reduced isovolumic relaxation time from 114 +/- 26 to 99 +/- 21 ms (p less than 0.01) and the time to peak rate of LV dimensional lengthening from 166 +/- 17 to 133 +/- 10 ms (p less than 0.01), without significant changes of LV dimensions or fractional shortening. No significant changes were observed in LV dimensions or fractional shortening, but a significant increase in peak rate of LV dimensional lengthening (from 4.1 +/- 1.5 to 4.8 +/- 1.6/s, p less than 0.05) and a reduction in isovolumic relaxation time (from 105 +/- 26 to 77 +/- 23 ms, p less than 0.01) and the time to peak rate of LV dimensional lengthening (from 156 +/- 23 to 124 +/- 20 ms, p less than 0.01) occurred during the oral administration of diltiazem. In contrast, propranolol caused no significant changes in these values. Thus, diltiazem improves LV relaxation and diastolic filling without altering LV systolic function in patients with hypertrophic cardiomyopathy.

Influence of left atrial function on Doppler transmitral and pulmonary venous flow patterns in dilated and hypertrophic cardiomyopathy: evaluation of left atrial appendage function by transesophageal echocardiography.

Information regarding the relation of left atrial (LA) function to transmitral and pulmonary venous (PV) flow is limited. Using transesophageal echocardiography, we analyzed this relation in 23 patients with dilated cardiomyopathy (DCM) and 25 patients with hypertrophic cardiomyopathy (HCM). Left atrial appendage (LAA) function was assessed as a substitute for overall LA function. Transmitral and PV flow-velocity variables, the LAA emptying flow velocity (LAA-A), and the LAA ejection fraction (LAA-EF) were determined. Each patient group was divided into two subgroups with a normal ( < 15 mm Hg) or elevated ( > or = 15 mm Hg) mean pulmonary wedge pressure (PWP). Transmitral and PV flow patterns as well as LA function were similar in the two subgroups with a normal PWP (11 patients with DCM and 14 patients with HCM). For the subgroups with an elevated PWP, however, the peak velocity ratio of the early filling wave (E) to atrial contraction wave (A) was higher in DCM patients (n = 12) than in HCM patients (n = 11) (2.1 +/- 0.7 vs 1.3 +/- 0.2; p < 0.01). This difference mostly resulted from a lower A velocity in the DCM group than in the HCM group (30 +/- 10 cm/sec vs 43 +/- 7 cm/sec; p < 0.05). In addition, the reverse flow velocity at atrial contraction in the PV was lower in the DCM group than in the HCM group (19 +/- 8 cm/sec vs 37 +/- 8 cm/sec; p < 0.01). These findings were associated with poorer LA systolic function in the DCM group (LAA-A, 35 +/- 13 cm/sec vs 60 +/- 11 cm/sec; LAA-EF, 37% +/- 12% vs 55% +/- 15%, p < 0.05, respectively). Our data suggest that a restrictive transmitral flow pattern develops more easily in DCM than in HCM because LA dysfunction is present in DCM, and that LA contractility plays an important role in determining the atrial contraction wave of transmitral and PV flows with elevated LA pressure.

Influence of altered loading conditions on left atrial appendage function in vivo

This study sought to examine the influence of heart failure treatment on left atrial (LA) appendage function in 10 patients with left ventricular dysfunction. After treatment of heart failure, LA appendage function markedly improved, less dependent on LA and left ventricular functions, which suggests that with altered loading conditions, LA appendage function changes chiefly through its intrinsic contractile property.

Left ventricular Doppler filling pattern in dilated cardiomyopathy: Relation to hemodynamics and left atrial function

This study attempted to examine the relation of left ventricular filling patterns to hemodynamic status and left atrial function in dilated cardiomyopathy. Transesophageal echocardiography and cardiac catheterization were performed in 41 patients with dilated cardiomyopathy (six with an ischemic origin). Transmitral, left atrial appendage, and pulmonary venous flow velocities were recorded with the pulsed Doppler method. Left atrial systolic function was assessed by the peak velocity of the left atrial appendage emptying wave and pulmonary venous flow reversal during atrial systole. Patients were classified into three groups according to their left ventricular filling patterns. Group 1 showed an abnormal relaxation pattern (E wave/A wave ratio <1, n = 17), group 2 had a normal or pseudonormal pattern (1 < or = E/A < 2, n = 11), and group 3 had a restrictive pattern (E/A > or = 2, n = 13). No differences were found among the groups with regard to age, gender, heart rate, and M-mode echocardiographic indices of left ventricular function. Compared with patients in group 1, those in groups 2 and 3 had more symptoms (New York Heart Association functional class III or IV) and had higher left ventricular filling pressures. The sensitivity of an E/A ratio > or = 1 for predicting a pulmonary capillary wedge pressure > or = 15 mm Hg was 75% and the specificity was 94%. Despite a similar increase of filling pressures, group 3 patients had a lower left atrial appendage emptying velocity, pulmonary venous flow reversal velocity, and mitral A velocity than did group 2 patients. The sensitivity and specificity of an E/A ratio > or = 22 for detecting left atrial dysfunction (left atrial appendage emptying velocity < or = 40 cm/sec) was 85% and 86%, respectively. In conclusion, among patients with dilated cardiomyopathy, those who had a restrictive or pseudonormal filling pattern were in a higher functional class and had higher filling pressures. Further studies are needed to determine the therapeutic and prognostic significance of left atrial dysfunction, which was common in patients with a restrictive pattern.

Incidence of the coexistence of left ventricular false tendons and premature ventricular contractions in apparently healthy subjects.

The incidence of the coexistence of left ventricular false tendons and premature ventricular contractions (PVCs) was evaluated prospectively. Over 14 months, left ventricular false tendons were found in 71 (6.4%) of 1117 consecutive patients examined echocardiographically. Two types of false tendons were observed: longitudinal, from the ventricular septum to the posteroapical wall (n = 62), and transverse, between the septum and the lateral wall (n = 9). Among 62 patients with PVCs and no underlying heart disease, false tendons were detected in 35 (56%); 28 had unifocal and seven had bifocal PVCs. Episodes of ventricular tachycardia were documented in one of the 28 patients with unifocal PVCs and in one of the seven patients with bifocal PVCs. These PVCs were poorly controlled by antiarrhythmic drugs but easily suppressed by exercise. Left ventricular false tendons were detected in 36 patients on routine echocardiographic examinations performed in the other 1055 subjects, and 10 of these patients were judged to have no underlying heart disease. PVCs were detected in two (20%) of these 10 patients. Although a definite conclusion that left ventricular false tendons are arrhythmogenic cannot be derived from these results, the unexpectedly high incidence of the coexistence suggests that left ventricular false tendons may be an etiologic factor in the development of PVCs, especially the rate-dependent and medically uncontrollable PVCs seen in apparently healthy individuals.

Spectrum of restrictive cardiomyopathy: Report of the national survey in Japan

This report describes clinical profiles and echocardiographic, hemodynamic, and histologic findings in 26 cases of idiopathic RCM based on the diagnostic criteria of (1) heart failure resulting from a stiff left ventricle, (2) normal LV size and systolic function, (3) absence of LV hypertrophy, and (4) cause or association unknown. There were 14 male and 12 female patients ranging in age from 5 to 63 years. Ten patients died during the mean follow-up period of 145 months, and five died of heart failure after 10 years. Three had a family history of HCM. Thromboembolism was observed in eight. Echocardiograms showed normal LV wall thickness and contraction. Hemodynamic characteristics included elevated biventricular filling pressures and a pulmonary wedge pressure that was usually higher than the right atrial pressure. Equalization of biventricular filling pressures was seen, however, in almost all patients with severe tricuspid regurgitation (seven of eight). The square root sign was seen in 50% in RV diastolic pressure tracings and 28% in LV tracings. This sign was observed in patients with elevated filling pressures. Interstitial fibrosis (22 of 23), endocardial thickening (13 of 23), and myofibrillar hypertrophy (10 of 23) were common histologic findings. Severe myocardial fiber disarray consistent with HCM was seen in four patients.

A Case of Cardiomyopathy Showing Progression From the Hypertrophic to the Dilated Form

This report describes a case of cardiomyopathy with a novel point mutation of mitochondrial DNA coding lysine tRNA in association with severe ultrastructural alterations of the mitochondria in the cardiomyocytes. Abnormalities of energy production and/or abnormal protein synthesis because of the mutation of mitochondrial DNA may have played an important role in the pathogenesis of this case, which showed severe cardiomyocyte degeneration and deterioration from hypertrophic cardiomyopathy to severe dilated cardiomyopathy.

Evolution to dilated cardiomyopathy from acute eosinophilic pancarditis in Churg-Strauss syndrome

SummaryWe describe the clinical manifestations of a patient with Churg-Strauss syndrome who presented with severe acute cardiac involvement and whose disease evolved to dilated cardiomyopathy (DCM), with special reference to the histopathological findings. Endomyocardial biopsies, conducted sequentially, three times within 10 months, revealed severe eosinophilic endomyocarditis in the acute phase, interstitial fibrosis in the subacute phase, and endocardial thickening with mural thrombi, at 10 months. Although acute inflammation associated with elevation of eosinophil granule proteins subsided with steroid therapy, left ventricular dilatation with reduced contractility progressed. A subgroup of DCM is not considered to be idiopathic but, rather, an aftereffect of hypereosinophilic heart disease.