Quantitative analysis of late gadolinium enhancement in hypertrophic cardiomyopathy.

BACKGROUND: Cardiovascular magnetic resonance (CMR) with the late gadolinium enhancement (LGE) technique allows the detection of myocardial fibrosis in Hypertrophic cardiomyopathy (HCM). The aim of this study was to compare different methods of automatic quantification of LGE in HCM patients. METHODS: Forty HCM patients (mean age 48 y, 30 males) and 20 normal subjects (mean age 38 y, 16 males) underwent CMR, and we compared 3 methods of quantification of LGE: 1) in the SD2 method a region of interest (ROI) was placed within the normal myocardium and enhanced myocardium was considered as having signal intensity >2 SD above the mean of ROI; 2) in the SD6 method enhanced myocardium was defined with a cut-off of 6 SD above mean of ROI; 3) in the RC method a ROI was placed in the background of image, a Rayleigh curve was created using the SD of that ROI and used as ideal curve of distribution of signal intensity of a perfectly nulled myocardium. The maximal signal intensity found in the Rayleigh curve was used as cut-off for enhanced myocardium. Parametric images depicting non enhanced and enhanced myocardium was created using each method. Three investigators assigned a score to each method by the comparison of the original LGE image to the respective parametric map generated. RESULTS: Patients with HCM had lower concordance between the measured curve of distribution of signal intensity and the Rayleigh curve than controls (63.7 +/- 12.3% vs 92.2 +/- 2.3%, p < 0.0001).A cut off of concordance < 82.9% had a 97.1% sensitivity and 92.3% specificity to distinguish HCM from controls. The RC method had higher score than the other methods. The average extent of enhanced myocardium measured by SD6 and Rayleigh curve method was not significant different but SD6 method showed underestimation of enhancement in 12% and overestimation in 5% of patients with HCM. CONCLUSIONS: Quantification of fibrosis in LGE images with a cut-off derived from the Rayleigh curve is more accurate than using a fixed cut-off.

Acidic fibroblast growth factor in the developing rat embryo.

Compared to basic fibroblast growth factor (bFGF), a widely distributed, broad spectrum mitogen and mesoderm inducer, acidic fibroblast growth factor (aFGF) is reported to have an essentially neural distribution and to be undetectable in the early embryo. In the present investigation, we used immunoblotting and immunochemistry to assess the cellular and tissue distributions of aFGF and bFGF in 11-20-d rat embryos. Immunoblotting of crude and heparin-bound embryo extracts revealed faint bands at the expected 17-18-kD and predominant bands at an apparent molecular mass of 26 to 28-kD (despite reducing conditions) using multiple specific antibodies for aFGF and bFGF. Pretreatment with 8 M urea yielded 18-20-kD aFGF and bFGF and some 24-26-kD bFGF. Immunoreactivity for both aFGF and bFGF was positive and similar in the cytoplasm, nuclei, and extracellular matrix of cells of neuroectodermal and mesodermal origin, while it was negative in endoderm-derived cells. The distribution of immunoreactive aFGF and bFGF also showed changes during development that were associated with the process of cellular and tissue differentiation. For example, intensity and extent of immunoreactivity for both peptides progressively increased in the middle layer of the spinal cord with increasing differentiation of the neural cells. The immunostaining patterns were very similar for aFGF and bFGF for each organ and at each stage. In conclusion, high molecular mass forms of immunoreactive aFGF and bFGF are present in the rat embryo. Acidic FGF and bFGF are both widely distributed in tissues of neuroectodermal and mesodermal origin, and their distribution was very similar.

An equivalent time temperature mapping system with a 320 x 256 pixels full-frame 100 kHz sampling rate.

In this paper we describe a novel temperature mapping system based on a standard infrared camera with 50 Hz frame rate for the measurement of ultrafast temperature transients which, in principle, demand for a much faster acquisition rate. In particular, we base our system on the widely used equivalent time sampling concept which can be adapted to the temperature acquisition system, thanks to a very fast and sensitive camera sensor: an InSb sensor, which allows a reduced integration time of 10 micros, and a custom digital synchronization circuit. The latter has been realized by the usage of a fully programmable digital circuit, which generates all the signals needed for the synchronization of the IR camera, of the experiment, and a personal computer needed for data acquisition and storage. We show, with experiments, how this system is capable of detecting temperature transients with an equivalent bandwidth of 100 kHz full frame, far beyond the capabilities of the fastest available IR cameras.

Epidemiology of hypertrophic cardiomyopathy-related death: revisited in a large non-referral-based patient population.

BACKGROUND: Death resulting from hypertrophic cardiomyopathy (HCM), particularly when sudden, has been reported to be largely confined to young persons. These data emanated from tertiary HCM centers with highly selected referral patterns skewed toward high-risk patients. METHODS AND RESULTS: The present analysis was undertaken in an international population of 744 consecutively enrolled and largely unselected patients more representative of the overall HCM spectrum. HCM-related death occurred in 86 patients (12%) over 8+/-7 years (mean+/-SD). Three distinctive modes of death were as follows: (1) sudden and unexpected (51%; age, 45+/-20 years); (2) progressive heart failure (36%; age, 56+/-19 years); and (3) HCM-related stroke associated with atrial fibrillation (13%; age, 73+/-14 years). Sudden death was most common in young patients, whereas heart failure- and stroke-related deaths occurred more frequently in midlife and beyond. However, neither sudden nor heart failure-related death showed a statistically significant, disproportionate age distribution (P=0.06 and 0.5, respectively). Stroke-related deaths did occur disproportionately in older patients (P=0.002). Of the 45 patients who died suddenly, most (71%) had no or mild symptoms, and 7 (16%) participated in moderate to severe physical activities at the time of death. CONCLUSIONS: HCM-related cardiovascular death occurred suddenly, or as a result of heart failure or stroke, largely during different phases of life in a prospectively assembled, regionally based, and predominantly unselected patient cohort. Although most sudden deaths occurred in adolescents and young adults, such catastrophes were not confined to patients of these ages and extended to later phases of life. This revised clinical profile suggests that generally held epidemiological tenants for HCM have been influenced considerably by skewed reporting from highly selected populations. These data are likely to importantly affect risk stratification and treatment strategies importantly for the prevention of sudden death in HCM.

Infective endocarditis in hypertrophic cardiomyopathy: prevalence, incidence, and indications for antibiotic prophylaxis.

BACKGROUND: The literature on infective endocarditis in hypertrophic cardiomyopathy (HCM) is virtually confined to case reports. Consequently, the risk of endocarditis in HCM remains undefined. METHODS AND RESULTS: We assessed the occurrence of endocarditis in 810 HCM patients evaluated between 1970 and 1997. Endocarditis was diagnosed in 10 patients, 2 of whom were excluded from analysis of prevalence and incidence because they were referred for acute endocarditis. At first evaluation, echocardiographic features consistent with prior endocarditis were identified in 3 of 808 patients, a prevalence of 3.7 per 1000 patients (95% CI, 0.8 to 11). Of 681 patients who were followed, 5 developed endocarditis, an incidence of 1.4 per 1000 person-years (95% CI, 0.5 to 3.2); outflow obstruction was present in each of these 5 patients and was associated with the risk of endocarditis (P=0.006). In the 224 obstructive patients, incidence of endocarditis was 3.8 per 1000 person-years (95% CI, 1.6 to 8.9) and probability of endocarditis 4. 3% at 10 years. Left atrial size was also associated with the risk of endocarditis (P=0.007). In patients with both obstruction and atrial dilatation (>/=50 mm), incidence of endocarditis increased to 9.2 per 1000 person-years (95% CI, 2.5 to 23.5). Analysis of all 10 patients with endocarditis identified outflow obstruction in each and atrial dilatation in 7. CONCLUSIONS: Endocarditis in HCM is virtually confined to patients with outflow obstruction and is more common in those with both obstruction and atrial dilatation. These results indicate that antibiotic prophylaxis is required only in patients with obstructive HCM.

Absence of progression of left ventricular hypertrophy in adult patients with hypertrophic cardiomyopathy.

Development or progression of left ventricular hypertrophy has recently been described in children with hypertrophic cardiomyopathy. To determine whether similar changes in magnitude and distribution of left ventricular hypertrophy may also occur in adult patients with this disease, serial assessment of left ventricular wall thickness was obtained with M-mode and two-dimensional echocardiography in 65 patients with hypertrophic cardiomyopathy who were 23 to 50 years of age. The follow-up period was 3 to 6 years (mean 4). None of the 65 patients showed a substantial increase (greater than or equal to 5 mm) in left ventricular wall thickness; however, 9 (14%) demonstrated a substantial decrease (5 to 9 mm). Wall thinning most commonly involved the anterior ventricular septum (seven patients), but was also identified in the posterior septum (six patients), lateral free wall (two patients) and posterior free wall (one patient). In the nine patients with wall thinning, left ventricular end-diastolic diameter increased significantly (from 44 +/- 6 to 51 +/- 6 mm; p less than 0.001); however, in seven of the nine, absolute cavity size remained within normal limits (less than or equal to 52 mm) at the most recent evaluation. Eight of the nine patients with left ventricular wall thinning and relative cavity enlargement were severely symptomatic and one was mildly symptomatic. In conclusion, substantial progression of left ventricular hypertrophy was not identified in any of the study patients. Hence, if such progression occurs in adults with hypertrophic cardiomyopathy, it is probably rare. Conversely, an important minority of adult patients with hypertrophic cardiomyopathy may show progressive left ventricular wall thinning and relative cavity enlargement, which are usually associated with severe cardiac symptoms.

Relation between extent of left ventricular hypertrophy and age in hypertrophic cardiomyopathy.

This investigation was undertaken to determine whether a relation could be identified between left ventricular wall thickness and age in a large population of symptomatic patients with hypertrophic cardiomyopathy. Extent of left ventricular hypertrophy was assessed with two-dimensional echocardiography in 173 patients with hypertrophic cardiomyopathy who ranged in age from 21 to 74 years (mean 45) and had mild to severe cardiac symptoms. The overall study group was classified into five age subgroups (each corresponding to a decade); maximal left ventricular wall thickness and wall thickness index (a quantitative expression of the overall extent of hypertrophy) were assessed in each group. These two indexes were significantly higher in patients 21 to 30 years of age than in patients in each of the other four older age groups. The two indexes of left ventricular hypertrophy were also significantly higher in patients 31 to 40 years of age than in patients who were 61 to 74 years old. Multivariate regression analysis showed that the relation between wall thickness and age was not influenced by other clinical variables such as severity of symptoms, presence of subaortic obstruction, left ventricular cavity dimension and gender. In conclusion, the findings indicate that, in a population of symptomatic adult patients with hypertrophic cardiomyopathy, left ventricular hypertrophy is considerably more severe in younger than in older patients and that there is an inverse relation between left ventricular wall thickness and age.

Relation between extent of left ventricular hypertrophy and diastolic filling abnormalities in hypertrophic cardiomyopathy.

In hypertrophic cardiomyopathy, the relation between left ventricular diastolic impairment and magnitude of left ventricular hypertrophy has not been clearly defined. In the present study, Doppler echocardiographic indexes of left ventricular diastolic filling were compared in 78 patients with hypertrophic cardiomyopathy and in 72 normal control subjects of similar age, and the relation between abnormalities of diastolic filling and magnitude of left ventricular hypertrophy was assessed. In patients with hypertrophic cardiomyopathy, isovolumic relaxation was prolonged (94 +/- 25 ms); peak early diastolic flow velocity (53 +/- 18 cm/s), deceleration of flow velocity in early diastole (341 +/- 142 cm/s2) and the ratio between early and late peaks of flow velocity (1.6 +/- 0.9) were reduced; and peak late diastolic flow velocity was increased (38 +/- 15 cm/s) compared with values in control subjects (76 +/- 12 ms, 65 +/- 12 cm/s, 512 +/- 131 cm/s2, 2.3 +/- 0.8 and 30 +/- 7 cm/s, respectively; p less than 0.001). Individual patient analysis showed that diastolic filling was abnormal in 52 (67%) of the 78 patients with hypertrophic cardiomyopathy. However, within the patient group, none of the Doppler diastolic indexes showed a significant correlation with maximal left ventricular wall thickness or the wall thickness index (correlation coefficients ranged from -0.15 to 0.10).(ABSTRACT TRUNCATED AT 250 WORDS)

Relation between extent of left ventricular hypertrophy and occurrence of sudden cardiac death in hypertrophic cardiomyopathy.

Sudden unexpected death can be the first clinical manifestation of hypertrophic cardiomyopathy and is the most devastating feature of the natural history of the disease. Left ventricular hypertrophy appears to be an important determinant of many clinical features of hypertrophic cardiomyopathy, but the relation between its magnitude and the occurrence of sudden cardiac death has not been clearly defined. In this study, the magnitude of hypertrophy was assessed with two-dimensional echocardiography in 29 asymptomatic or mildly symptomatic patients with hypertrophic cardiomyopathy who subsequently died suddenly or experienced cardiac arrest with documented ventricular fibrillation. Findings were compared with those obtained in a control group of 95 patients of similar age and symptomatic state. Maximal left ventricular wall thickness was significantly greater in patients with sudden death (26 +/- 7 mm) than in control patients (21 +/- 5 mm, p less than 0.001). Left ventricular wall thickness index, a quantitative expression of the overall extent of hypertrophy, was also greater in patients with sudden death (76 +/- 20 mm) than in surviving control patients (62 +/- 13 mm, p less than 0.001). Particularly marked and diffuse hypertrophy, with maximal wall thickness greater than or equal to 30 mm or wall thickness greater than or equal to 25 mm in two or more of the four segments into which the left ventricle had been divided, was eight times more common in patients with sudden death (11 [38%] of 29) than in control patients (5 [5%] of 95, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive assessment of left ventricular diastolic function: comparative analysis of Doppler echocardiographic and radionuclide angiographic techniques.

This investigation was performed to determine whether variables obtained directly from the Doppler left ventricular diastolic flow velocity profile provide a reliable estimate of diastolic function. Measurements of diastolic flow velocity obtained by Doppler echocardiography were compared with volumetric measurements of left ventricular diastolic filling determined by radionuclide angiography in 12 subjects without cardiac disease and in 25 patients with a variety of cardiac diseases. The two methods were in agreement in distinguishing normal from abnormal diastolic function in 21 (84%) of the 25 patients with cardiac disease, identifying diastolic function as normal in 8 and abnormal in 13 of these patients. Good correlations were observed between certain Doppler variables of left ventricular diastolic flow velocity and radionuclide angiographic variables of left ventricular filling. The time interval from the aortic closing component of the second heart sound to the end of the early diastolic flow velocity peak, assessed with Doppler echocardiography, correlated well with the time interval from end-systole to the end of rapid filling, assessed with radionuclide angiography (r = 0.83). Descent of the Doppler early diastolic flow velocity peak correlated well with the radionuclide angiographic peak filling rate (r = 0.79). The ratio between the heights of the early and late (due to atrial systole) peaks of diastolic flow velocity showed good correlation with the ratio between percent of left ventricular filling during rapid filling and during atrial systole (r = 0.76). These findings demonstrate that the left ventricular diastolic flow velocity profile obtained with Doppler echocardiography compares favorably with radionuclide angiographic variables in the evaluation of left ventricular diastolic function.(ABSTRACT TRUNCATED AT 250 WORDS)

Severe functional limitation in patients with hypertrophic cardiomyopathy and only mild localized left ventricular hypertrophy.

Ten patients with nonobstructive hypertrophic cardiomyopathy and only mild localized left ventricular hypertrophy who had severe symptoms of cardiac failure are described. During a mean follow-up period of 7 years, 6 of these 10 patients showed a substantial increase in left ventricular internal dimension (6 to 15 mm, mean 10) as assessed with M-mode echocardiography, although absolute left ventricular cavity size remained within normal limits in 5 of the 6. Four patients demonstrated substantial septal thinning (5 to 14 mm, mean 8). Left ventricular diastolic function, assessed by radionuclide angiography in nine patients, was impaired in eight who showed decreased peak filling rate (less than 2.5 end-diastolic volumes/s) and prolonged time to peak rate of filling (greater than or equal to 180 ms). Furthermore, left ventricular systolic function, usually supernormal in patients with hypertrophic cardiomyopathy, was depressed (ejection fraction less than or equal to 45%) in six patients. Hence, a subset of patients was identified with nonobstructive hypertrophic cardiomyopathy and only mild localized left ventricular hypertrophy who experienced severe cardiac symptoms. The majority of these patients showed both systolic and diastolic left ventricular dysfunction in the presence of a progressive increase in left ventricular internal dimension (but without absolute left ventricular dilation) or ventricular septal thinning or both. Such patients may represent an important component of the natural history of hypertrophic cardiomyopathy which has not been previously fully appreciated.

Unusual distribution of left ventricular hypertrophy in obstructive hypertrophic cardiomyopathy: localized posterobasal free wall thickening in two patients.

Two patients with hypertrophic cardiomyopathy and a previously unreported distribution of left ventricular hypertrophy are described. Each patient showed substantial wall thickening that was confined to the posterobasal segment of the left ventricular free wall, as well as evidence of dynamic subaortic obstruction. This observation emphasizes the fact that hypertrophic cardiomyopathy is characterized by a broad morphologic spectrum. Furthermore, it demonstrates a unique circumstance in which left ventricular outflow tract obstruction may occur in the absence of anterior and basal septal hypertrophy.

Noninvasive assessment of left ventricular diastolic function by pulsed Doppler echocardiography in patients with hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy is a primary myocardial disease in which symptoms may frequently result from impaired left ventricular relaxation, filling and compliance. In the present investigation, Doppler echocardiography was utilized to measure transmitral flow velocity and thereby assess left ventricular diastolic performance noninvasively in a group of 111 patients representative of the broad clinical spectrum of hypertrophic cardiomyopathy. In patients with hypertrophic cardiomyopathy, all Doppler indexes of diastolic relaxation and filling differed significantly (p less than 0.001) from those obtained in 86 control subjects without heart disease, namely, prolongation of isovolumic relaxation (94 +/- 24 versus 78 +/- 12 ms) and of the early diastolic peak of flow velocity (244 +/- 55 versus 220 +/- 28 ms), as well as slower deceleration (3.4 +/- 1.4 versus 4.9 +/- 1.3 m/s2) and reduced maximal flow velocity in early diastole (0.5 +/- 0.2 versus 0.6 +/- 0.1 m/s). As an apparent compensation for impaired relaxation and early diastolic filling, the atrial contribution to left ventricular filling was increased, as shown by increased late diastolic flow velocity (0.4 +/- 0.3 versus 0.3 +/- 0.1 m/s) and reduced ratio of maximal flow velocity in early diastole to that in late diastole (1.4 +/- 0.8 versus 2.1 +/- 0.9). The vast majority of patients with hypertrophic cardiomyopathy (91 [82%] of 111) showed evidence of impaired left ventricular diastolic performance, as assessed from the Doppler waveform. Abnormal Doppler diastolic indexes were identified with similar frequency in patients with (78%) or without (83%) left ventricular outflow obstruction, as well as in patients with (84%) or without (80%) cardiac symptoms. However, patients with nonobstructive hypertrophic cardiomyopathy showed more severe alterations in the Doppler indexes of diastolic function than did patients with obstruction. Thus, abnormal diastolic performance as assessed by Doppler echocardiography was apparent in the vast majority of the study patients with hypertrophic cardiomyopathy, independent of the presence or absence of cardiac symptoms or a subaortic pressure gradient. The high frequency with which diastolic abnormalities are identified in asymptomatic patients with hypertrophic cardiomyopathy suggests that impaired diastolic performance may be present at a time in the natural history of the disease when functional limitation is not yet evident.

Quantitative assessment of ultrasonic myocardial reflectivity in hypertrophic cardiomyopathy.

The purpose of this study was to investigate the relation between acoustic properties of the myocardium and magnitude of left ventricular hypertrophy in patients with hypertrophic cardiomyopathy. An on-line radio frequency analysis system was used to obtain quantitative operator-independent measurements of the integrated backscatter signal of the ventricular septum and posterior free wall in 25 patients with hypertrophic cardiomyopathy and 25 normal age-matched control subjects. The integrated values of the radio frequency signal were normalized for the pericardial interface and expressed in percent. Tissue reflectivity was significantly increased in the hypertrophied ventricular septum, as well as in the nonhypertrophied posterior free wall, in patients with hypertrophic cardiomyopathy (58 +/- 15% and 37 +/- 12%, respectively) compared with values in normal subjects (33 +/- 10% and 18 +/- 5%, respectively; p less than 0.001). Furthermore, measurements of reflectivity of the septum or posterior free wall, or both, were beyond 2 SD of normal values in greater than 90% of the patients and were also abnormal in each of the five study patients who had only mild and localized left ventricular hypertrophy. No correlation was identified between myocardial tissue reflectivity and left ventricular wall thickness in the patients with hypertrophic cardiomyopathy (correlation coefficient r = 0.4; p = NS). These findings demonstrate that myocardial reflectivity is abnormal in most patients with hypertrophic cardiomyopathy and is largely independent of the magnitude of left ventricular hypertrophy. Moreover, quantitative analysis of ultrasonic reflectivity can differentiate patients with hypertrophic cardiomyopathy from normal subjects independently of clinical features and conventional echocardiographic measurements.

Clinical features of hypertrophic cardiomyopathy caused by mutation of a "hot spot" in the alpha-tropomyosin gene.

OBJECTIVES: We studied the clinical and genetic features of familial hypertrophic cardiomyopathy (FHC) caused by an Asp175Asn mutation in the alpha-tropomyosin gene in affected subjects from three unrelated families. BACKGROUND: Correlation of genotype and phenotype has provided important information in FHC caused by beta-cardiac myosin and cardiac troponin T mutations. Comparable analyses of hypertrophic cardiomyopathy caused by alpha-tropomyosin mutations have been hampered by the rarity of these genetic defects. METHODS: The haplotypes of three kindreds with FHC due to an alpha-tropomyosin gene mutation, Asp175Asn, were analyzed. The cardiac histopathologic findings of this mutation are reported. Distribution of left ventricular hypertrophy in affected members was assessed by two-dimensional echocardiography, and patient survival rates were compared. RESULTS: Genetic studies defined unique haplotypes in the three families, demonstrating that independent mutations caused the disease in each. The Asp175Asn mutation caused cardiac histopathologic findings of myocyte hypertrophy, disarray and replacement fibrosis. The severity and distribution of left ventricular hypertrophy varied considerably in affected members from the three families (mean maximal wall thickness +/- SD: 24 +/- 4.5 mm in anterior septum of Family DT; 15 +/- 2.7 mm in anterior septum and free wall of Family DB; 18 +/- 2.1 mm in posterior septum of Family MI), but survival was comparable and favorable. CONCLUSIONS: Nucleotide residue 579 in the alpha-tropomyosin gene may have increased susceptibility to mutation. On cardiac histopathologic study, defects in this sarcomere thin filament component are indistinguishable from other genetic etiologies of hypertrophic cardiomyopathy. The Asp175Asn mutation can elicit different morphologic responses, suggesting that the hypertrophic phenotype is modulated not by genetic etiologic factors alone. In contrast, prognosis reflected genotype; near normal life expectancy is found in hypertrophic cardiomyopathy caused by the alpha-tropomyosin mutation Asp175Asn.

Patterns of systolic anterior motion of the mitral valve in hypertrophic cardiomyopathy: assessment by two-dimensional echocardiography.

A variety of patterns of systolic anterior motion (SAM) of the mitral valve were identified by realtime, 2-dimensional echocardiography in 62 patients with hypertrophic cardiomyopathy. In 36 patients (58%), both the anterior and posterior mitral leaflets appeared to participate importantly in SAM, although the anterior leaflet actually contacted or most closely approached the ventricular septum during systole because of its anterior anatomic position. In 19 patients (31%), SAM was produced selectively by the posterior mitral leaflet. In only 6 patients (10%) was the anterior leaflet alone responsible for SAM. In just 1 patient did the chordae tendineae appear to be primarily responsible for the SAM. In 51 patients (82%), only the distal portion of the anterior or posterior mitral leaflet (and possibly the attached proximal chordae tendineae) approached or contacted the septum in systole; in 10 patients both the body and tip regions of the anterior leaflet produced mitral-septal apposition. Hence, in obstructive hypertrophic cardiomyopathy, (1) the morphologic structures responsible for moderate to severe SAM are not identical in all patients, and a variety of patterns of SAM occur; (2) the posterior mitral leaflet plays an important role in SAM in almost 90% of patients, either by producing SAM alone (31%) or by moving anteriorly in concert with the anterior leaflet (58%); (3) SAM produced selectively by the anterior mitral leaflet is relatively uncommon; and (4) SAM is usually produced primarily by the distal portions of the mitral leaflets (with or without the attached chordae tendineae).

Implications of left ventricular remodeling in hypertrophic cardiomyopathy.

Left ventricular remodeling occurs spontaneously among patients with hypertrophic cardiomyopathy in several ways: (1) wall thickening in children; (2) wall thinning associated with cavity enlargement in midlife; and possibly (3) a very gradual wall thinning process occurring over long periods of time in adulthood.

Degree of left ventricular hypertrophy in patients with hypertrophic cardiomyopathy and chronic atrial fibrillation.

It has been generally assumed that most patients with hypertrophic cardiomyopathy (HC) who develop atrial fibrillation (AF) have marked left ventricular (LV) hypertrophy and subaortic obstruction. The morphologic and functional features of this subset of patients with HC have not been systematically investigated. The LV morphology and functional profile of 46 patients with HC and chronic AF were compared with those of 81 control patients with HC and normal sinus rhythm. Contrary to expectations, LV hypertrophy (assessed with 2-dimensional echocardiography) was substantially less marked in the patients with AF than in the control patients, and prevalence of subaortic obstruction was similar in the 2 groups. Maximal LV wall thickness and wall thickness index were lower in patients with AF (18 +/- 2 and 56 +/- 7 mm, respectively) than in control patients (22 +/- 6 and 67 +/- 16 mm, respectively; p less than 0.001). Furthermore, mild LV hypertrophy (maximal LV wall thickness less than or equal to 17 mm confined to 1 ventricular segment) was almost twice as frequent in patients with AF (63%) than in control patients (36%; p less than 0.005). Subaortic obstruction was present in 9 patients with AF (20%) and in 28 control patients (35%; p greater than 0.05). In a subgroup of 22 patients with AF who were followed for 4 to 10 years, 5 patients had marked LV wall thinning (greater than or equal to 5 mm, range 5 to 14). In conclusion, these results demonstrate that most patients with HC and chronic AF have the nonobstructive form of HC, and relatively mild LV hypertrophy.

Relation between extent of left ventricular hypertrophy and occurrence of ventricular tachycardia in hypertrophic cardiomyopathy.

This study was undertaken to determine whether the occurrence of ventricular tachycardia (VT) in patients with hypertrophic cardiomyopathy (HC) is related to the magnitude and extent of left ventricular (LV) hypertrophy. Extent of LV hypertrophy was assessed using 2-dimensional echocardiography in 30 patients with HC in whom VT had been documented on 24-hour ambulatory electrocardiographic (ECG) monitoring, and the extent of LV hypertrophy in these patients was compared with that of a control group of 61 patients with HC who had normal ambulatory ECG recordings. Severe LV hypertrophy, involving at least 3 of the 4 LV segments, occurred significantly more often in patients with documented VT (16 of 30, 53%) than in those with normal ambulatory ECG findings (13 of 61, 21%; p less than 0.002). Conversely, mild LV hypertrophy, involving only 1 LV segment, occurred significantly less often in patients with VT (5 of 30, 17%) than in the control subjects (32 of 61, 52%; p less than 0.001). Moderate LV hypertrophy, involving 2 of the 4 LV segments, occurred about as frequently in patients with VT (9 of 30, 30%) as in patients with normal ambulatory ECG findings (16 of 61, 26%; p greater than 0.05). In addition, the LV wall thickness index, a quantitative measure of overall extent of LV hypertrophy, was also significantly higher (thereby indicating a greater magnitude of hypertrophy) in patients with documented VT (72 +/- 17 mm) than in those with normal ambulatory ECG recordings (61 +/- 14 mm; p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Left atrial appendage function assessed by transesophageal echocardiography before and on the day after elective cardioversion for nonvalvular atrial fibrillation.

We investigated left atrial appendage function by transesophageal echocardiography, on the day after external electrical cardioversion to sinus rhythm, in 41 patients with nonvalvular atrial fibrillation. After cardioversion, appendage contraction synchronized with the electrical and mechanical activity of the atrium, which was restored in about 70% of the patients.