Circulating miR-29a, among other up-regulated microRNAs, is the only biomarker for both hypertrophy and fibrosis in patients with hypertrophic cardiomyopathy

OBJECTIVES

The purpose of this paper was to determine whether microRNAs (miRNAs) involved in myocardial remodeling were differentially expressed in the blood of hypertrophic cardiomyopathy (HCM) patients, and whether circulating miRNAs correlated with the degree of left ventricular hypertrophy and fibrosis.

BACKGROUND

miRNAs-small, noncoding ribonucleic acids (RNAs) that regulate gene expression by inhibiting RNA translation-modulate cellular function. Myocardial miRNAs modulate processes such as cardiomyocyte (CM) hypertrophy, excitation-contraction coupling, and apoptosis; non-CM-specific miRNAs regulate myocardial vascularization and fibrosis. Recently, the possibility that circulating miRNAs may be biomarkers of cardiovascular disease has been raised.

METHODS

Forty-one HCM patients were characterized with conventional transthoracic echocardiography and cardiac magnetic resonance. Peripheral plasma levels of 21 miRNAs were assessed by quantitative real-time polymerase chain reaction and were compared with levels in a control group of 41 age- and sex-matched blood donors.

RESULTS

Twelve miRNAs (miR-27a, -199a-5p, -26a, -145, -133a, -143, -199a-3p, -126-3p, -29a, -155, -30a, and -21) were significantly increased in HCM plasma. However, only 3 miRNAs (miR-199a-5p, -27a, and -29a) correlated with hypertrophy; more importantly, only miR-29a correlated also with fibrosis.

CONCLUSIONS

Our data suggest that cardiac remodeling associated with HCM determines a significant release of miRNAs into the bloodstream: the circulating levels of both cardiac- and non-cardiac-specific miRNAs are significantly increased in the plasma of HCM patients. However, correlation with left ventricular hypertrophy parameters holds true for only a few miRNAs (i.e., miR-199a-5p, -27a, and -29a), whereas only miR-29a is significantly associated with both hypertrophy and fibrosis, identifying it as a potential biomarker for myocardial remodeling assessment in HCM.

Speckle-tracking analysis based on 2D echocardiography does not reliably measure left ventricular torsion

PURPOSE

Worldwide left ventricular (LV) twist is measured by 2D speckle tracking acquiring apical short axis at a LV level where papillary muscles are no longer visible; however, we hypothesized that this methodological recommendation is not enough accurate to obtain a reliable measurement of apical rotation.

METHODS

We measured twist and untwist rate in 30 healthy subjects by following the earlier method. By 3D echocardiography, we identified two LV apex levels: (i) 3D Apex, defined as the last apical slice at which LV cavity was visible; (ii) 2D Apex, defined as the level where diameters are equal to those of apical LV short axis used for twist analysis in the same subject. The ratio between the distance of 2D Apex and 3D Apex from LV base was calculated and expressed as percentage (2D Apex/3D Apex).

RESULTS

2D Apex/3D Apex was strongly related to the magnitude of twist and untwisting rate (r = 0·82, P<0·001; r = -0·46, P = 0·015, respectively). The only determinant of twist was 2D Apex/3D Apex (r(2)  = 0·68; r = 0·82; F ratio: 52·6, P<0·001); whereas untwisting rate was influenced by 2D Apex/3D Apex and age (r(2)  = 0·42; r = 0·65; F ratio: 7·7; P = 0·003 for 2D Apex/3D Apex; and P = 0·011 for age).

CONCLUSIONS

Left ventricular apical level acquisition, even when recorded in a standard manner, determines variability of twist mechanics measurements. Thus, current anatomical markers used to identify LV apex for twist analysis are not reliable and need different standardization. 3D echocardiography may help in such standardization.

Percutaneous treatment of patients with heart diseases: selection, guidance and follow-up. A review

Aortic stenosis and mitral regurgitation, patent foramen ovale, interatrial septal defect, atrial fibrillation and perivalvular leak, are now amenable to percutaneous treatment. These percutaneous procedures require the use of Transthoracic (TTE), Transesophageal (TEE) and/or Intracardiac echocardiography (ICE). This paper provides an overview of the different percutaneous interventions, trying to provide a systematic and comprehensive approach for selection, guidance and follow-up of patients undergoing these procedures, illustrating the key role of 2D echocardiography.

Echocardiography in patients with hypertrophic cardiomyopathy: usefulness of old and new techniques in the diagnosis and pathophysiological assessment

Hypertrophic cardiomyopathy (HCM) is one of the most common inherited cardiomyopathy. The identification of patients with HCM is sometimes still a challenge. Moreover, the pathophysiology of the disease is complex because of left ventricular hyper-contractile state, diastolic dysfunction, ischemia and obstruction which can be coexistent in the same patient. In this review, we discuss the current and emerging echocardiographic methodology that can help physicians in the correct diagnostic and pathophysiological assessment of patients with HCM.

Myocardial fibrosis and diastolic dysfunction in patients on chronic haemodialysis

BACKGROUND

Left ventricular (LV) diastolic dysfunction is linked to myocardial collagen content in many cardiac diseases. There are no data regarding such relationship in patients with end-stage renal disease (ESRD) undergoing haemodialysis.

METHODS

Twenty-five patients with ESRD undergoing haemodialysis were studied by echocardiography. LV diastolic function was investigated by Doppler echocardiography, by analysing LV filling velocities at rest and during loading manoeuvres, which represent an estimate of LV filling pressure. According to the Doppler pattern, LV filling pressure in a given patient was judged to be normal or slightly increased or to be moderately or severely increased. The presence of myocardial fibrosis was estimated by ultrasound tissue characterization with integrated backscatter, which in diastole correlates with the collagen content of the myocardium.

RESULTS

Integrated backscatter was higher in patients with moderate or severely increased than in patients with normal or slightly increased LV filling pressure (integrated backscatter: 51.0 +/- 9.8 vs 41.6 +/- 5.6%; P = 0.008). Integrated backscatter was a strong and independent determinant of diastolic dysfunction (odds ratio = 1.212; P = 0.040).

CONCLUSION

Our data support the hypothesis that, in a selected population of patients with ESRD undergoing haemodialysis, myocardial fibrosis is associated with LV diastolic myocardial properties.

Thrombosis of mechanical valve prosthesis in patient with recent Caesarean delivery

We present a case of a mechanical mitral valve thrombosis in a 37-year-old woman occurred 2 days after a Caesarean delivery. The patient stopped warfarin and initiated low-molecular-weight heparin 1 week before the programmed delivery. Subsequently the diagnosis of thrombosis, heparin infusion was started however unsuccessfully and eventually patient was referred for cardiac surgery.

Diastolic function and BNP changes during exercise predict oxygen consumption in chronic heart failure patients

B-type natriuretic peptide (BNP) is a diagnostic and prognostic marker in heart failure (CHF) patients.

AIM

To assess the relation between BNP, diastolic function and exercise capacity in CHF patients.

METHODS

Fifty CHF patients underwent cardiopulmonary exercise testing. BNP levels were determined at baseline and at peak exercise. Patients were divided in two groups: with lower (<14 ml/kg/min) or higher (>or=14 ml/kg/min) peak oxygen consumption (VO(2)).

RESULTS

Seventeen patients with lower peak VO(2) showed larger incidence of restrictive pattern of the transmitral flow (7/17 vs 4/33, p =0.036). E/Ea ratio was inversely related with peak VO(2) (r =-0.419, p =0.004) and directly related with BNP levels at baseline (r =0.449, p =0.001) and at peak exercise (r =0.475, p =0.001). LV ejection fraction was similar in the two groups. Independent predictors of exercise tolerance were E/Ea ratio (p =0.003), lg BNP at baseline (p =0.034) and increase in lg BNP during exercise (p =0.038).

CONCLUSIONS

In CHF patients, E/Ea ratio is a predictor of exercise tolerance and is related with BNP level at rest and at peak exercise.

Resolution of established cardiac hypertrophy and fibrosis and prevention of systolic dysfunction in a transgenic rabbit model of human cardiomyopathy through thiol-sensitive mechanisms

BACKGROUND

Cardiac hypertrophy, the clinical hallmark of hypertrophic cardiomyopathy (HCM), is a major determinant of morbidity and mortality not only in HCM but also in a number of cardiovascular diseases. There is no effective therapy for HCM and generally for cardiac hypertrophy. Myocardial oxidative stress and thiol-sensitive signaling molecules are implicated in pathogenesis of hypertrophy and fibrosis. We posit that treatment with N-acetylcysteine, a precursor of glutathione, the largest intracellular thiol pool against oxidative stress, could reverse cardiac hypertrophy and fibrosis in HCM.

METHODS AND RESULTS

We treated 2-year-old beta-myosin heavy-chain Q403 transgenic rabbits with established cardiac hypertrophy and preserved systolic function with N-acetylcysteine or a placebo for 12 months (n=10 per group). Transgenic rabbits in the placebo group had cardiac hypertrophy, fibrosis, systolic dysfunction, increased oxidized to total glutathione ratio, higher levels of activated thiol-sensitive active protein kinase G, dephosphorylated nuclear factor of activated T cells (NFATc1) and phospho-p38, and reduced levels of glutathiolated cardiac alpha-actin. Treatment with N-acetylcysteine restored oxidized to total glutathione ratio, normalized levels of glutathiolated cardiac alpha-actin, reversed cardiac and myocyte hypertrophy and interstitial fibrosis, reduced the propensity for ventricular arrhythmias, prevented cardiac dysfunction, restored myocardial levels of active protein kinase G, and dephosphorylated NFATc1 and phospho-p38.

CONCLUSIONS

Treatment with N-acetylcysteine, a safe prodrug against oxidation, reversed established cardiac phenotype in a transgenic rabbit model of human HCM. Because there is no effective pharmacological therapy for HCM and given that hypertrophy, fibrosis, and cardiac dysfunction are common and major predictors of clinical outcomes, the findings could have implications in various cardiovascular disorders.

Evaluation of the left ventricular anatomy in hypertrophic cardiomyopathy: comparison between echocardiography and cardiac magnetic resonance imaging

AIM

The aim of this study was to assess the relationship between echocardiographic indexes of left ventricular (LV) hypertrophy with LV mass (LVM) obtained at cardiac magnetic resonance (CMR) in a population of patients with hypertrophic cardiomiopathy (HCM).

METHODS

Thirty-nine patients with HCM underwent echocardiography and CMR. By echocardiography maximal wall thickness (MWT), Spirito' and Maron's hypertrophy index and the Wigle's score were obtained. Absolute LVM was measured through CMR and indexed to body surface area (LVMi). Data were analysed using linear regression analysis.

RESULTS

In 31% of patients there was an incomplete echocardiographic LV anatomic characterization. However, there was a good correlation between MWT measured at echocardiography and at CMR (P<0.001; r=0.755). Overall echocardiographic indexes of LV hypertrophy correlate with either LVM and LVMi: MWT (P=0.008, r=0.420 and P=0.003, r=0.467, respectively); Spirito' and Maron's hypertrophy index (P=0.003, r=0.551 and P=0.001, r=0.606, respectively) and Wigle's score (P=0.004, r=0.522 and P=0.004, r=0.522, respectively).

CONCLUSION

In our HCM population, although a complete anatomic LV anatomic characterization was not obtained by echocardiography in all patients, echocardiographic hypertrophic indexes showed a good correlation with LVM obtained by CMR.

Pathogenesis of hypertrophic cardiomyopathy. Impact of growth factors on left ventricular anatomy

AIM

The aim of this study was to evaluate the effect of insulin-like growth factor 1 (IGF1) and transforming growth factor beta-1 (TGFbeta-1) on collagen turnover, left ventricular (LV) hypertrophy and on passive diastolic function of the LV in hypertrophic cardiomyopathy (HCM).

METHODS

This study group comprised 34 patients with non-dilated HCM. Procollagen I amino-terminal propeptide (PINP) and collagen I carboxy-terminal telopeptide (ICTP) were measured by radioimmunoassay. Matrix metalloproteinase 9 (MMP 9), IGF1 and TGFalfa-1 were determined by enzyme-linked immunosorbent assay. The difference in duration between transmitral forward (A) and pulmonary venous retrograde (Ar) waves, was considered as an estimate of passive diastolic function; the ratio between the peak flow velocity at rapid filling at the mitral level (E) and E' measured by tissue Doppler was considered an estimate of active diastolic function. LV mass was measured and normalized to body surface area (LVMi) by cardiac magnetic resonance imaging.

RESULTS

LVMi correlates to E/E' (r=0.597, P=0.019 ) and is inversely related to A-Ar (r=0.453, P=0.015). TGFbeta-1 is directly related to active MMP 9 (r=0.439, P=0.012 ). IGF1 is directly related to PICP-ICTP (r=0.347, P=0.501), that expresses the balance between collagen I synthesis and its degradation.

CONCLUSION

The study demonstrated that in HCM, LVMi influences active and passive diastolic dysfunction and that IGF1 stimulates collagen synthesis and TGFbeta-1 is related to LV hypertrophy.

Myocardial Texture in Hypertrophic Cardiomyopathy

BACKGROUND

This study was conceived to assess associations between integrated backscatter signal at end diastole (IBS) and diastolic properties in patients with hypertrophic cardiomyopathy.

METHODS

In 46 patients with hypertrophic cardiomyopathy, septal IBS was calculated by both applying an appropriate regression correction (IBSc) and by relating it to pericardial reflectivity (IBSp). Difference in duration between transmitral forward and pulmonary venous backward velocities (A-Ar) was measured as an estimate of passive diastolic filling. In all, 38 patients underwent ambulatory electrocardiogram monitoring for 48 hours.

RESULTS

IBS inversely correlated to both A-Ar (IBSc, r = -.522, P < .001; IBSp, r = -.302, P = .041) and mitral peak velocity at atrial contraction (IBSc, r = -.464, P = .002; IBSp, r = -.413, P = .004). Moreover, IBS was greater in patients with sustained or nonsustained ventricular tachycardia (IBSc, 28.5 +/- 3.8 vs 25.4 +/- 3.8 dB, P = .034).

CONCLUSIONS

Septal IBS correlates with Doppler parameters of left ventricular chamber stiffness in patients with hypertrophic cardiomyopathy. Increased IBS is associated with presence of ventricular arrhythmias.

Abnormal blood-pressure response to exercise and oxygen consumption in patients with hypertrophic cardiomyopathy

BACKGROUND

Abnormal blood-pressure response during exercise occurs in about one third of patients with hypertrophic cardiomyopathy (HCM), and it has been associated with a high risk of sudden cardiac death. We assessed the hemodynamics of exercise in HCM patients with abnormal blood-pressure response by using ambulatory radionuclide monitoring (VEST) of left-ventricular (LV) function, and exercise tolerance by oxygen consumption.

METHODS

Twenty-two HCM patients underwent treadmill exercise during VEST monitoring. A cardiopulmonary exercise test was performed a few days after. The VEST data were averaged for 1 minute. Stroke volume, cardiac output, and systemic vascular resistance were expressed as percent of baseline. Exercise tolerance was assessed as maximal oxygen consumption.

RESULTS

In eight HCM patients (36%) with an abnormal blood-pressure response, end-systolic volume increased more (52% +/- 21% vs 31% +/- 28%, P = .012), and the ejection fraction (-31% +/- 17% vs -14% +/- 22%, P = .029) and stroke volume (-21% +/- 21% vs 3% +/- 28%, P = .026) fell more, than in patients with normal response. Cardiac output increased less in the former patients (49% +/- 44% vs 94% +/- 44%, P = .012). Systemic vascular resistance decreased similarly, irrespective of blood-pressure response (-28% +/- 26% vs -34% +/- 26%, P = N.S.). Percent of maximal predicted oxygen consumption was lower in HCM patients with an abnormal blood-pressure response (63% +/- 11% vs 78% +/- 15%, P = .025).

CONCLUSIONS

In HCM patients, abnormal blood-pressure response was associated with exercise-induced LV systolic dysfunction and impairment in oxygen consumption. This may cause hemodynamic instability, associated with a high risk of sudden cardiac death.

Implantable cardioverter-defibrillators and prevention of sudden cardiac death in hypertrophic cardiomyopathy

CONTEXT

Recently, the implantable cardioverter-defibrillator (ICD) has been promoted for prevention of sudden death in hypertrophic cardiomyopathy (HCM). However, the effectiveness and appropriate selection of patients for this therapy is incompletely resolved.

OBJECTIVE

To study the relationship between clinical risk profile and incidence and efficacy of ICD intervention in HCM.

DESIGN, SETTING, AND PATIENTS

Multicenter registry study of ICDs implanted between 1986 and 2003 in 506 unrelated patients with HCM. Patients were judged to be at high risk for sudden death; had received ICDs; underwent evaluation at 42 referral and nonreferral institutions in the United States, Europe, and Australia; and had a mean follow-up of 3.7 (SD, 2.8) years. Measured risk factors for sudden death included family history of sudden death, massive left ventricular hypertrophy, nonsustained ventricular tachycardia on Holter monitoring, and unexplained prior syncope.

MAIN OUTCOME MEASURE

Appropriate ICD intervention terminating ventricular tachycardia or fibrillation.

RESULTS

The 506 patients were predominately young (mean age, 42 [SD, 17] years) at implantation, and most (439 [87%]) had no or only mildly limiting symptoms. ICD interventions appropriately terminated ventricular tachycardia/fibrillation in 103 patients (20%). Intervention rates were 10.6% per year for secondary prevention after cardiac arrest (5-year cumulative probability, 39% [SD, 5%]), and 3.6% per year for primary prevention (5-year probability, 17% [SD, 2%]). Time to first appropriate discharge was up to 10 years, with a 27% (SD, 7%) probability 5 years or more after implantation. For primary prevention, 18 of the 51 patients with appropriate ICD interventions (35%) had undergone implantation for only a single risk factor; likelihood of appropriate discharge was similar in patients with 1, 2, or 3 or more risk markers (3.83, 2.65, and 4.82 per 100 person-years, respectively; P = .77). The single sudden death due to an arrhythmia (in the absence of advanced heart failure) resulted from ICD malfunction. ICD complications included inappropriate shocks in 136 patients (27%).

CONCLUSIONS

In a high-risk HCM cohort, ICD interventions for life-threatening ventricular tachyarrhythmias were frequent and highly effective in restoring normal rhythm. An important proportion of ICD discharges occurred in primary prevention patients who had undergone implantation for a single risk factor. Therefore, a single marker of high risk for sudden death may be sufficient to justify consideration for prophylactic defibrillator implantation in selected patients with HCM.

Prognostic significance of left atrial size in patients with hypertrophic cardiomyopathy (from the Italian Registry for Hypertrophic Cardiomyopathy)

This study assessed left atrial (LA) dimension as a potential predictor of outcome in hypertrophic cardiomyopathy (HC). From the Italian Registry for Hypertrophic Cardiomyopathy, 1,491 patients (mean age 47 +/- 17 years; 61% men; 19% obstructive), followed for 9.4 +/- 7.4 years after the initial echocardiographic evaluation, constituted the study group. The mean LA transverse dimension was 43 +/- 9 mm and was larger in patients with severe symptoms (48 +/- 9 mm for New York Heart Association classes III and IV vs 42 +/- 9 mm for classes I and II, p <0.001), atrial fibrillation (47 +/- 9 vs 42 +/- 8 mm in sinus rhythm, p <0.001), and left ventricular outflow obstruction (46 +/- 9 mm for >or=30 mm Hg at rest vs 42 +/- 9 mm for <30 mm Hg at rest, p <0.001). On univariate analysis, each 5-mm increase in LA size was associated with a hazard ratio (HR) of 1.2 for all-cause mortality (p <0.0001). On multivariate analysis, a LA dimension >48 mm (the 75th percentile) had a HR of 1.9 for all-cause mortality (p = 0.008), 2.0 for cardiovascular death (p = 0.014), and 3.1 for death related to heart failure (p = 0.008) but was unassociated with sudden death (p = 0.81). Similar results were obtained after the exclusion of patients with atrial fibrillation (HR 1.7, p = 0.008) or outflow obstruction (HR 1.8, p = 0.003). The predictive power of LA dimension >48 mm was also validated in an independent HC cohort from the United States, with similar HRs (1.8 for all-cause mortality, p = 0.019). In conclusion, in a large cohort of patients with HC from a nationwide registry, a marked increase in LA dimension were predictive of long-term outcome, independent of co-existent atrial fibrillation or outflow obstruction. LA dimension is a novel and independent marker of prognosis in HC, particularly relevant to the identification of patients at risk for death related to heart failure.

Effect of hypertrophy on left ventricular diastolic function in patients with hypertrophic cardiomyopathy

Background.

Hypertrophic cardiomyopathy (HCM) is characterized by asymmetric LV hypertrophy (LVH) and impairment in diastolic function. We assess the relationship between LVH and invasive indexes of diastolic function.

Methods.

21 HCM patients underwent cardiac catheterization to assess pulmonary capillary wedge pressure, LV end-diastolic pressure (measured by microtip catheters), and LV volumes (calculated by simultaneous radionuclide angiography). We calculated from LV pressure the time constant of isovolumetric relaxation (τ, variable asymptote method, ms), and from LV pressure and volume the constant of chamber stiffness (k, ml⁻¹). LVH was assessed by different indexes: maximal wall thickness, number of hypertrophied LV segments, LVH index, and Wigle’s score. Results. Wigle’s score was directly related to pulmonary capillary Wedge pressure (r=0.436, p=0.048), peak V wave of pulmonary capillary wedge pressure (r=0.503, p=0.024), LV end-diastolic pressure (r=0.643, p=0.002) and k (r=0.564, p=0.015). HCM patients were divided into 2 groups according to Wigle’s score: 10 with mild or moderate LVH (< 8), and 11 with severe LVH (≥ 8). HCM patients with severe LVH showed a higher pulmonary capillary Wedge pressure (15.1±7.2 vs 9.5±2.4, p=0.033), peak V wave of pulmonary capillary wedge pressure (20.7±4.6 vs 14.6±4.9, p=0.011), LV end-diastolic pressure (23.9±10.9 vs 10.6±2.5, p=0.002), k (0.0465±0.032 vs 0.015±0.007, p=0.022) and LV outflow tract gradient (72±36 mmHg vs 29±30 mmHg, p=0.01).τ was similar in the two groups. Other indexes of LVH were not related to diastolic function.

Conclusions.

Wigle’s score is the only index of LVH that relates to invasive indices of diastolic function.

The Italian Registry for hypertrophic cardiomyopathy: a nationwide survey

BACKGROUND

National registries are advocated as instrumental to the solution of rarity-related problems for patients with hypertrophic cardiomyopathy (HCM), including limited access to advanced treatment options. Thus, an Italian Registry for HCM was created to assess the clinical profile and the level of care nationwide of patients with HCM.

METHODS

Cardiology centers over the national territory were recruited to provide clinical data of all patients with HCM ever seen at each institution. The enrollment period was from May 2000 to May 2002.

RESULTS

The registry enrolled 1677 patients from 40 institutions. Most (69%) were followed at referral centers, whereas 31% were from community centers with intermediate-low patient flow. Patients diagnosed after routine medical examinations or familial screenings were 39%. Most patients were male (62%), in their fourth to sixth decade of life, and in New York Heart Association class I to II (89%); 24% had resting left ventricular obstruction and 18% had atrial fibrillation. During a 9.7-year average follow-up, cardiovascular mortality was 1%/y, mostly because of heart failure, with no significant change over the last 3 decades; sudden death was less common (0.4%/y). Only 4% of patients received a defibrillator; 14% of the 401 patients with LV outflow obstruction underwent invasive relief of obstruction; and <1% were offered genetic analyses or counseling.

CONCLUSIONS

The Italian Registry represents the first comprehensive attempt to evaluate the clinical impact and management of HCM at a national level. Findings underscore the role of screening strategies for an early diagnosis and suggest limited use of the advanced therapeutic options for HCM.

Long-Term Effects of Surgical Septal Myectomy on Survival in Patients With Obstructive Hypertrophic Cardiomyopathy

OBJECTIVES

This study sought to determine the impact of surgical myectomy on long-term survival in hypertrophic cardiomyopathy (HCM).

BACKGROUND

Left ventricular (LV) outflow tract obstruction in HCM increases the likelihood of heart failure and cardiovascular death. Although surgical myectomy is the primary treatment for amelioration of outflow obstruction and advanced drug-refractory heart failure symptoms, its impact on long-term survival remains unresolved.

METHODS

Total and HCM-related mortality were compared in three subgroups comprised of 1,337 consecutive HCM patients evaluated from 1983 to 2001: 1) surgical myectomy (n = 289); 2) LV outflow obstruction without operation (n = 228); and 3) nonobstructive (n = 820). Mean follow-up duration was 6 +/- 6 years.

RESULTS

Including two operative deaths (procedural mortality, 0.8%), 1-, 5-, and 10-year overall survival after myectomy was 98%, 96%, and 83%, respectively, and did not differ from that of the general U.S. population matched for age and gender (p = 0.2) nor from patients with nonobstructive HCM (p = 0.8). Compared to nonoperated obstructive HCM patients, myectomy patients experienced superior survival free from all-cause mortality (98%, 96%, and 83% vs. 90%, 79%, and 61%, respectively; p < 0.001), HCM-related mortality (99%, 98%, and 95% vs. 94%, 89%, and 73%, respectively; p < 0.001), and sudden cardiac death (100%, 99%, and 99% vs. 97%, 93%, and 89%, respectively; p = 0.003). Multivariate analysis showed myectomy to have a strong, independent association with survival (hazard ratio 0.43; p < 0.001).

CONCLUSIONS

Surgical myectomy performed to relieve outflow obstruction and severe symptoms in HCM was associated with long-term survival equivalent to that of the general population, and superior to obstructive HCM without operation. In this retrospective study, septal myectomy seems to reduce mortality risk in severely symptomatic patients with obstructive HCM.

Determinants of atrial fibrillation development in patients with hypertrophic cardiomyopathy

Predictors of the development of atrial fibrillation (AF) in patients who have hypertrophic cardiomyopathy (HC) have not been extensively studied, although, in these patients, AF contributes to the exacerbation of symptoms and the development of heart failure. The present study determined the role of left atrial (LA) function in the development of AF in patients who have HC. One hundred fifty consecutive patients who had HC, had no history of AF, and who were followed for 5.2 +/- 2.9 years constituted the study population. Using M-mode echocardiography, we measured LA function as global LA fractional shortening and LA diameter. LA volume was measured from 2-dimensional 4-chamber views by the method of disks. During follow-up, 20 patients developed AF. LA function was an independent predictor of AF (odds ratio 0.716, p = <0.001), whereas LA diameter and volume were predictors in addition to age. Kaplan-Meier analysis showed that LA dysfunction carried a high risk of AF. Thus, in patients who have HC, LA function is a strong predictor of AF development and is independent of age.

Dobutamine stress echocardiography in hypertrophic cardiomyopathy

AIMS

Myocardial ischemia in the absence of coronary artery disease is common in patients with hypertrophic cardiomyopathy (HCM). Dobutamine stress echocardiography (DSE) induces left ventricular (LV) new wall motion abnormalities (NWMA) in some patients with HCM. We evaluated the effects of dobutamine on LV performance and hemodynamics in HCM.

METHODS AND RESULTS

Eighteen patients with non-obstructive HCM underwent DSE. Dobutamine was administered at dosages of 5, 10, 20, 30 and 40 microg/kg/min with increments at intervals of 3 min. Seven patients developed NWMA, whereas the other 11 did not. During DSE, heart rate increased significantly more in NWMA patients,whereas LV outflow tract gradient (OTG) increased significantly and similarly in both groups. At peak dobutamine dose, NWMA patients had a significant increase in LV end-systolic diameter and volume and a significant decrease in LV fractional shortening and ejection fraction. Posterior wall thickening increased significantly, whereas septal thickening did not increase throughout DSE in both groups.

CONCLUSIONS

In a subgroup of patients with HCM, DSE induces NWMA, associated with a greater increase in heart rate, irrespective of LVOTG. NWMA induce a depression of global LV systolic performance. The septum shows no contractile reserve, regardless of NWMA. These phenomena may be the result of induction of ischemia and/or impaired LV systolic function due to fast heart rate.

Abnormal QT interval variability in patients with hypertrophic cardiomyopathy

We sought to determine QT variability pattern in patients with hypertrophic cardiomyopathy (HCM) and its relationship with the risk of syncope. QT interval variability was assessed from 24-hour Holter monitoring in 10 HCM patients with history of syncope, 10 HCM patients without history of syncope, and 10 healthy subjects. QT variability was higher in patients with HCM, in particular in those with history of syncope, than in healthy controls. Time domain QT variability did not vary between waking and sleeping hours in HCM patients, whereas it was significantly shorter while asleep in the control group. Increased QT SDANN identified HCM patients with history of syncope with an accuracy of 75%. Our data show that QT variability is abnormal in HCM patients and indirectly support the concept that arrhythmia-related syncope in these patients may be, at least in part, related to an altered control of repolarization.

Sympathetic nervous function in patients with hypertrophic cardiomyopathy assessed by [123I]-MIBG: relationship with left ventricular perfusion and function

AIM

The aim of the present study was to evaluate [123I] MIBG uptake and clearance in patients with hypertrophic cardiomyopathy (HCM) and to assess their relationships with left ventricular function (systolic and diastolic) and perfusion.

METHODS

Eleven consecutive patients with HCM (8 men and 3 women; mean age 38+/-12 years, none in the dilated phase) underwent (in separate days, in random order) [123I]-MIBG scintigraphy, [(99m)Tc]-MIBI SPET at rest, and echocardiography. All patients were studied in fasting condition, and all medications were discontinued. [(99m)Tc]-MIBI SPET study was performed 1 hour after tracer injection. [123I]-MIBG study was acquired 5 minutes (planar) and 4 hours (planar and SPET) after the i.v. injection of [123I]-MIBG. Heart to mediastinum ratio (H/M) was computed at 4 hours. Wash out rate (WOR) was computed as: (H early - H delayed)/(H early), after decay correction. Both [123I]-MIBG and [(99m)Tc]-MIBI SPET were analyzed on 3 short axis views (apical, middle, and basal). Left ventricular outflow tract gradient (LVOTG), ejection fraction, volumes, septum thickness, and left atrial fractional shortening (LAFS) were evaluated on echocardiography.

RESULTS

[123I]-MIBG WOR showed a positive relationship with LVOTG (r=0.84, p<0.001) and septum thickness (r=0.76, p<0.01), while a negative one was found with LAFS (r= -0.66, p<0.05). The study group was divided into: Group A (n=5) with higher, and Group B (n=6) with lower WOR than the median value (i.e. 11%). Group A patients had significantly lower LAFS (17.6+/-4.8 vs 26.8+/-7.2%, p<0.05), higher LVOTG (49+/-35 vs 3+/-3 mmHg), and thicker septum (21+/-2 vs 17+/-2 mm) than Group B patients. Inferior and septal wall [123I]-MIBG uptake on 4 hour SPET was significantly lower in Group A than in Group B. On the other hand, no differences were found in (99m)T-MIBI SPET rest regional uptake between the 2 subgroups of patients.

CONCLUSION

These results suggest that cardiac sympathetic activity correlates to cardiac anatomy (i.e. degree of hypertrophy) and diastolic function in patients with HCM.

Myocardial collagen turnover in hypertrophic cardiomyopathy

BACKGROUND

Myocardial interstitial fibrosis is a characteristic of hypertrophic cardiomyopathy (HCM). This study evaluates the collagen turnover in HCM and its impact on left ventricular (LV) diastolic function.

METHODS AND RESULTS

Thirty-six HCM patients and 14 sex- and age-matched controls were studied. Collagen turnover was assessed as follows. By radioimmunoassay, a byproduct of collagen III synthesis (PIIINP) and 3 peptides resulting from collagen I synthesis (PICP and PINP) and degradation (ICTP) were measured. By ELISA, matrix metalloproteinases (MMPs) were determined, as follows: active MMP-2; active MMP-9; and MMP-1 as active, free (as active MMP-1 plus its precursor), and total (as free MMP-1 plus MMP-1/tissue inhibitor complexes). Tissue inhibitor of metalloproteinases-1 (TIMP-1) was also assayed. All patients underwent echocardiography. The difference in duration between transmitral forward (A) and pulmonary venous retrograde (AR) waves (A-Ar) was considered an estimate of passive diastolic function. Furthermore, restrictive or pseudonormal LV filling patterns were considered to identify patients with passive diastolic dysfunction. Patients had higher levels of PIIINP, ICTP, MMP-2, MMP-9, and total TIMP-1 than did controls. PIIINP was inversely related to LV end-diastolic diameter. A-Ar was inversely related to PICP, PINP, and their differences with ICTP (estimates of collagen I buildup). Furthermore, A-Ar was directly related to MMP-1 and MMP-2.

CONCLUSIONS

As compared with controls, collagen turnover is enhanced in HCM patients. As collagen I synthesis prevails over degradation and MMP-1 and MMP-2 are inhibited, passive diastolic dysfunction occurs in patients with HCM.

[Myocardial interstitial fibrosis and diastolic dysfunction in hypertrophic cardiomyopathy]

Hypertrophic cardiomyopathy is an autosomal dominant disease characterized by asymmetrical left ventricular hypertrophy, myocyte disarray, interstitial fibrosis, and small vessel disease. More than 100 mutations in 10 genes, all encoding for sarcomeric proteins, have been identified as responsible for this disease. While the etiology of hypertrophic cardiomyopathy has been extensively elucidated, its pathogenesis is not completely understood. Mutated proteins are incorporated in the sarcomere and impair myocyte contractility. This probably triggers the compensatory local release of trophic factors, which influence the development of the typical anatomical features of the disease. Modifying genes or the effect of environmental or local factors is likely to play a role. Interstitial fibrosis is a morphological characteristic of hypertrophic cardiomyopathy and, increasing chamber stiffness, is an important determinant of diastolic dysfunction. Studies on transgenic animals with hypertrophic cardiomyopathy emphasize the role of interstitial fibrosis in this disease. Recently our group has shown that collagen turnover, evaluated through serum markers of collagen metabolism, is more active in patients with hypertrophic cardiomyopathy than in normal subjects and that patients with passive diastolic dysfunction accumulate collagen I. These studies are potentially relevant as they allow to assess the effects of therapy with cardioreparatory drugs.

Massive chronic atrial thrombosis

We report herein a patient in whom a very large and old thrombus in the left atrium was detected by transesophageal echocardiography. The patient started warfarin and aspirin. After 2 years of therapy, transesophageal echocardiography showed the complete resolution of thrombus in the absence of clinical evidence of embolism. This case indicates that large and presumably organized thrombi may be dissolved by an anticoagulant therapy, although the lytic activity of warfarin has never been demonstrated. Transesophageal echocardiography helps in the identification and follow-up of such conditions and contributes to understanding of warfarin action in left atrial thrombosis.

Aetiology and pathogenesis of hypertrophic cardiomyopathy

The term hypertrophic cardiomyopathy is used to describe an autosomal dominant cardiac disorder, characterized by myocyte hypertrophy and disarray, interstitial fibrosis and small vessel disease, with or without macroscopic hypertrophy. More than 100 mutations in ten genes, all encoding sarcomeric proteins, have been identified as responsible for this disease. Mutations in the genes for beta-myosin heavy chain, myosin binding protein-C, and cardiac troponin T are the most common. Other genes involved are alpha-tropomyosin, cardiac troponin-I, essential and regulatory light chains, alpha-cardiac actin, titin, and alpha-myosin heavy chain. Some mutations are more frequently associated with a given phenotype, but no particular phenotype is mutation specific; in fact, some mutations exhibit highly variable clinical, electrocardiographic and echocardiographic manifestations. This variability in the phenotypic manifestations is probably due to the influence of environmental factors and/or modifier genes. While the aetiology of hypertrophic cardiomyopathy has been extensively elucidated, its pathogenesis is not completely understood. Mutated proteins are incorporated in the sarcomere and impair myocyte contractility. This probably triggers the compensatory local release of trophic factors, which influence the development of the typical anatomical features of the disease, with a pathway similar to that observed in secondary, pressure overload hypertrophy.

CONCLUSIONS

The various pathological cardiac changes seen in hypertrophic cardiomyopathy are probably due to a compensatory response to impaired myocyte function resulting from mutations in the genes encoding sarcomeric proteins.

Hemodynamic effects of isometric exercise in hypertrophic cardiomyopathy: comparison with normal subjects

BACKGROUND

We assessed the hemodynamic effects of isometric exercise by an ambulatory radionuclide monitoring device (VEST) that measured left ventricular function in patients who had hypertrophic cardiomyopathy (HCM), with and without significant left ventricular outflow-tract obstruction at rest, compared with control subjects.

METHODS AND RESULTS

We studied 10 patients with obstructive HCM, 25 patients with nonobstructive HCM, and 11 control subjects. During VEST monitoring, all patients gripped a dynamometer at 75% of maximal strength for up to 5 minutes. End-diastolic, end-systolic, and stroke volumes; cardiac output; and systemic vascular resistance were expressed as a percentage of baseline. The mean exercise duration was similar among the 3 groups. During handgrip, heart rate, systolic blood pressure, and cardiac output increased significantly and similarly in the 3 groups. There was a significant difference in the lung activity between obstructive and nonobstructive HCM patients and control subjects (P <.001), with a fall in control subjects and no change in HCM patients, irrespective of obstruction. Control subjects showed a decrease in end-systolic volume (P =.02) and an increase in ejection fraction (P =.003) and stroke volume (P =.009), whereas these parameters did not change in HCM patients, irrespective of obstruction. Systemic vascular resistance increased in obstructive (P =.02) and nonobstructive (P <.01) HCM patients but did not change in control subjects.

CONCLUSIONS

Isometric exercise causes an abnormal and similar adaptation to load changes in obstructive and nonobstructive HCM patients, as compared with control subjects.

Effect of left ventricular outflow tract obstruction on clinical outcome in hypertrophic cardiomyopathy

BACKGROUND

The influence of left ventricular outflow tract obstruction on the clinical outcome of hypertrophic cardiomyopathy remains unresolved.

METHODS

We assessed the effect of outflow tract obstruction on morbidity and mortality in a large cohort of patients with hypertrophic cardiomyopathy who were followed for a mean (+/-SD) of 6.3+/-6.2 years.

RESULTS

Of the 1101 consecutive patients, 273 (25 percent) had obstruction of left ventricular outflow under basal (resting) conditions with a peak instantaneous gradient of at least 30 mm Hg. A total of 127 patients (12 percent) died of hypertrophic cardiomyopathy, and 216 surviving patients (20 percent) had severe, disabling symptoms of progressive heart failure (New York Heart Association [NYHA] functional class III or IV). The overall probability of death related to hypertrophic cardiomyopathy was significantly greater among patients with outflow tract obstruction than among those without obstruction (relative risk, 2.0; P=0.001). The risk of progression to NYHA class III or IV or death specifically from heart failure or stroke was also greater among patients with obstruction (relative risk, 4.4; P<0.001), particularly among patients 40 years of age or older (P<0.001). Age-adjusted multivariate analysis confirmed that outflow tract obstruction was independently associated with an increased risk of both death related to hypertrophic cardiomyopathy (relative risk, 1.6; P=0.02) and progression to NYHA class III or IV or death from heart failure or stroke (relative risk, 2.7; P<0.001). The likelihood of severe symptoms and death related to outflow tract obstruction did not increase as the gradient increased above the threshold of 30 mm Hg.

CONCLUSIONS

In patients with hypertrophic cardiomyopathy, left ventricular outflow tract obstruction at rest is a strong, independent predictor of progression to severe symptoms of heart failure and of death.

Depth variation bias and interaction with gain setting in ultrasonic tissue characterization by integrated backscatter analysis

Integrated backscatter signal (IBS) has been proposed as a tool to measure cardiac fibrosis. To overcome problems associated with machine settings and attenuation of the chest wall, IBS has been expressed in relation to posterior pericardium, as a variation across cardiac cycle, or both. Depth of the reflecting structure has never been considered as a source of variability. Accordingly, we studied the effect of structure depth on IBS and examined its interaction with gain setting. Backscatter signals were recorded from plastic phantoms containing identical structures set at increasing depth and in 1 healthy volunteer using silicone spacers to modify depth, on a wide range of gain settings. In the phantom, IBS signal linearly decreased with increasing depth and nonlinearly increased with increasing gain (all r(2) > 0.97). In the healthy volunteer, results from septum were very similar to the phantom experiment. Values of septal IBS were adjusted using multiple regression coefficients for gain and depth from the phantom experiment and resulted in a near-complete offset of effect of depth and gain on septal IBS (P = not significant for both gain and depth). These assumptions were also used to compare IBS analysis between hypertensive patients and patients with hypertrophic cardiomyopathy. Thus, depth and its relation with gain should be taken into account and might be almost fully predicted. Using appropriate regression modeling may allow analysis in optimal imaging conditions, tolerating between-patient comparisons even in limited diastolic frames.

Dual chamber pacing in hypertrophic cardiomyopathy: long-term effects on diastolic function

To assess the effects of chronic dual chamber pacing (DDD) on LV diastolic function in obstructive hypertrophic cardiomyopathy (HCM), 21 patients with obstructive HCM paced for refractory symptoms were studied at baseline and at 3 and 12 months. HCM patients were matched to 21 patients with obstructive HCM on conventional treatment. Left atrial fractional shortening was calculated by M-mode echocardiography; this index reflects LV end-diastolic pressure. LV outflow tract gradient decreased 65 +/- 21% with DDD pacing and the NYHA class improved (P = 0.033). Left atrial fractional shortening worsened with DDD pacing (P < 0.001). Patients with abnormal baseline left atrial fractional shortening (< 16%) were older, had a higher NYHA class, and had more severe mitral regurgitation. In this subgroup, left atrialfractional shortening did not worsen with DDD pacing and the NYHA class improved more than in patients with normal left atrialfractional shortening (P = 0.033). In conclusion, chronic DDD pacing reduces obstruction but impairs diastolic function in HCM. In patients with normal diastolic function, the untoward effects of pacing on diastolic function are more evident than in patients with abnormal diastolic function at baseline. This suggests that DDD pacing might be beneficial in a subgroup of patients with obstructive HCM and abnormal diastolic function.

Hemodynamic determinants of exercise-induced abnormal blood pressure response in hypertrophic cardiomyopathy

OBJECTIVES

We sought to assess the hemodynamics of exercise in patients with hypertrophic cardiomyopathy (HCM), with and without an exercise-induced abnormal blood pressure (BP) response, by ambulatory radionuclide monitoring of left ventricular (LV) function with the VEST device (Capintec Inc., Ramsey, New Jersey).

BACKGROUND

Blood pressure fails to increase >20 mm Hg during exercise in about one-third of patients with HCM. This carries a high risk of sudden death.

METHODS

Forty-three patients with HCM and 14 control subjects underwent maximal symptom-limited exercise on a treadmill during VEST. The VEST data were averaged for 1 min and analyzed at baseline, 3 min and peak exercise. The LV end-diastolic, end-systolic and stroke volumes, cardiac output and systemic vascular resistance were expressed as the percentage of baseline.

RESULTS

Ejection fraction and stroke volume fell in patients with HCM, although they increased in control subjects (p < 0.001 and p = 0.002, respectively). Cardiac output increased significantly more in control subjects than in patients with HCM (p = 0.001). In 17 patients with HCM (39%) with an abnormal BP response, ejection fraction and stroke volume fell more (p = 0.032 and p = 0.009, respectively) and cardiac output increased less (p = 0.001) than they did in patients with HCM with a normal BP response. Systemic vascular resistance decreased similarly in patients with HCM, irrespective of the BP response.

CONCLUSIONS

In patients with HCM with and without an abnormal BP response, abnormal hemodynamic adaptation to exercise was qualitatively similar but quantitatively different. An abnormal BP response was associated with exercise-induced LV systolic dysfunction. This causes hemodynamic instability, associated with a high risk of sudden cardiac death.

Comparison of hemodynamic adaptation to orthostatic stress in patients with hypertrophic cardiomyopathy with or without syncope and in vasovagal syncope

This study was designed to investigate whether, in patients with hypertrophic cardiomyopathy (HC), tilt-induced volume unloading triggers a peripheral reflex similar to that seen in patients with a history of vasovagal syncope or rather acts through an intrinsic cardiac mechanism secondary to diastolic dysfunction. Thirty-seven patients with HC (10 with and 27 without a history of syncope), 10 patients with vasovagal syncope, and 9 controls underwent 70 degrees head-up tilt for 45 minutes during continuous radionuclide monitoring of left ventricular function. We focused on the initial 5 minutes into the tilt test, well before symptoms occurred, to exclude that the observed hemodynamic changes were the consequence rather than the cause of syncope. HC patients with previous syncope and vasovagal patients experienced significant hypotension after the initial 5 minutes of tilt. Only HC patients with a history of syncope had a significant decrease in cardiac output, which began at the initial stage of the test. Systemic vascular resistance decreased in vasovagal patients, but increased in the HC syncopal group. Baseline peak filling rate was lower (2.4 +/- 0.5 vs 3.3 +/- 1.1 stroke counts/s, p = 0.03) and a "pseudonormal" or a restrictive pattern of left ventricular filling was more frequent (70% vs 26%, p = 0.02) in HC patients with than without a history of syncope. Thus, significant hypotension or frank syncope during orthostatic stress in HC patients with a history of syncope is due to an early decrease in cardiac output, which occurs well before the onset of symptoms; such impaired hemodynamic adaptation seems to be related to diastolic dysfunction.

Determinants and clinical significance of natriuretic peptides and hypertrophic cardiomyopathy

AIMS

Atrial and brain natriuretic peptide levels closely reflect impaired left ventricular function in patients with heart failure. In the present study we assessed the determinants and the clinical significance of atrial and brain natriuretic peptide plasma levels in hypertrophic cardiomyopathy.

METHODS AND RESULTS

In 44 patients with hypertrophic cardiomyopathy (40+/-15 years) we evaluated: (a) atrial and brain natriuretic peptide plasma levels; (b) left ventricular hypertrophy; (c) left ventricular ejection fraction; (d) transmitral and pulmonary venous flow velocity patterns, and left atrial fractional shortening; (e) left ventricular outflow tract gradient; (f) maximal oxygen consumption. Left ventricular hypertrophy influenced only brain natriuretic peptide levels (r=0.32;P<0.05). Atrial and brain natriuretic peptide plasma levels did not correlate with left ventricular ejection fraction, but correlated with left ventricular outflow tract gradient (r=0.35;P<0.05; and r=0.40, P=0.022, respectively) and left atrial fractional shortening (r=-0.57;P<0.001, and r=-0.35;P<0.05, respectively). Atrial but not brain natriuretic peptide plasma levels were inversely related to maximal oxygen consumption (r=-0.35;P<0.05). By stepwise multiple regression analysis, left atrial fractional shortening and left ventricular outflow tract gradient were the only predictors of atrial and brain natriuretic peptide plasma levels, respectively.

CONCLUSIONS

In hypertrophic cardiomyopathy, atrial natriuretic peptide plasma levels are mainly determined by diastolic function: this explains the relationship with exercise tolerance. In contrast, brain natriuretic peptide plasma levels are mainly determined by left ventricular outflow tract gradient.

Dual chamber pacing in hypertrophic cardiomyopathy: influence of atrioventricular delay on left ventricular outflow tract obstruction

The impact of the duration of atrioventricular (AV) delay on obstruction in hypertrophic cardiomyopathy was evaluated in 12 patients by cardiac catheterization, and in 8 of them also by Doppler echocardiography. The AV delay was programmed in random order at 125, 100 and 75 ms in the invasive study and at 120, 100 and 80 ms after pacemaker implantation. The arterial pressure did not changed throughout the studies, whereas the gradient decreased significantly by reducing the AV delay value; the greater gradient reduction was obtained, in both studies, with the AV delay set between 75 or 80 and 100 ms. QRS duration increased significantly by reducing the AV delay during both studies. The widest QRS was not associated with the smallest gradient in all patients. Changes in gradients were similar during the invasive and noninvasive protocols.

Exercise capacity in hypertrophic cardiomyopathy depends on left ventricular diastolic function

Some studies have demonstrated that left ventricular (LV) diastolic function is the principal determinant of impaired exercise capacity in hypertrophic cardiomyopathy (HC). In this study we sought the capability of echocardiographic indexes of diastolic function in predicting exercise capacity in patients with HC. We studied 52 patients with HC while they were not on drugs;12 of them had LV tract obstruction at rest. Diastolic function was assessed by M-mode and Doppler echocardiography by measuring: (1) left atrial fractional shortening, and the slope of posterior aortic wall displacement during early atrial emptying on M-mode left atrial tracing; and (2) Doppler-derived transmitral and pulmonary venous flow velocity indexes. Exercise capacity was assessed by maximum oxygen consumption by cardiopulmonary test during cycloergometer upright exercise. Maximum oxygen consumption correlated with the left atrial fractional shortening (r = 0.63, p <0.001), the slope of posterior aortic wall displacement during early atrial emptying (r = 0.55, p <0.001), age (r = -0.50; p <0.001), pulmonary venous diastolic anterograde velocity (r = 0.41, p <0.01), and the systolic filling fraction (r = -0.43; p <0.01). By stepwise multiple linear regression analysis, left atrial fractional shortening and the pulmonary venous systolic filling fraction were the only determinants of the maximum oxygen consumption (multiple r = 0.70; p <0.001). Exercise capacity did not correlate with Doppler-derived transmitral indexes. Thus, in patients with HC, exercise capacity was determined by passive LV diastolic function, as assessed by the left atrial M-mode and Doppler-derived pulmonary venous flow velocities.

Determinants of aortic artifacts during transesophageal echocardiography of the ascending aorta

BACKGROUND

The origin of artifacts of the ascending aorta during transesophageal echocardiography has not been widely studied. This study was undertaken to investigate in vivo whether anatomic features could determine the appearance of artifacts.

METHODS AND RESULTS

Transesophageal echocardiograms of 46 patients studied for suspected dissection with proven diagnosis (30 patients with and 16 without ascending aortic dissection) were reviewed. The incidence of artifacts was 46%, and it was similar in patients with and those without dissection (chi-square 0.516; P = not significant). Artifacts were located in the aortic lumen twice as far from the transducer as the atrial-aortic interface. The aortic diameter was larger in patients with than in those without artifacts (6.4 +/- 1.1 vs 4.2 +/- 0.9 cm, P <.001). An aortic diameter >5 cm and an atrial-aortic ratio </=0.6 predicted the artifact appearance with good sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy; these parameters reached a value of 100% by analysis only of patients without dissection.

CONCLUSIONS

An ascending aortic diameter >5.0 cm that exceeds the left atrial diameter with an atrial-aortic ratio </=0.6 creates in vivo the conditions for the reverberation of the atrial-aortic interface within the aorta. Therefore, in patients with such anatomic features, artifacts must be suspected in the presence of linear structures within the aorta.

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.

Influence of left ventricular cavity size on clinical presentation in hypertrophic cardiomyopathy

The aim of this study was to assess whether left ventricular (LV) cavity size relates to functional impairment and syncope in patients with hypertrophic cardiomyopathy (HC). LV diastolic dysfunction influences functional limitation in HC. A reduced LV end-diastolic dimension may underlie impaired diastolic properties and be implicated in hemodynamic syncope. Eighty-two consecutive patients with HC (off drugs, in sinus rhythm) underwent echocardiography to measure LV end-diastolic dimension in the short-axis view (indexed to the body surface area) and radionuclide angiography (n = 50) to calculate peak filling rate (normalized to stroke counts/s). Patients in New York Heart Association functional classes II to IV had smaller LV end-diastolic dimension (23.2 +/- 2.6 vs 25.5 +/- 2.5 mm/M2, p = 0.0001) and lower peak filling rate (4.3 +/- 1.4 vs 5.1 +/- 1.3 stroke counts/s, p = 0.036) than those in New York Heart Association class I. LV end-diastolic diameter was correlated to peak filling rate (r = 0.37; p = 0.008). The most potent predictors of functional limitation were LV end-diastolic dimension (relative risk [RR] 0.63, confidence interval [CI] 0.45 to 0.88; p = 0.008), age (RR 1.09, CI 1.03 to 1.17; p = 0.003), and LV thickness score (RR 1.08, CI 1.02 to 1.13; p = 0.003). LV cavity size was smaller in patients with functional limitation irrespective of obstruction and hypertrophy. Patients with differed from those without a history of syncope for a smaller LV end-diastolic dimension (23.2 +/- 2.5 vs 25.0 +/- 2.7 mm/M2, p = 0.008), which was the only independent predictor of syncope (RR 0.77, CI 0.63 to 0.95; p = 0.013). Thus, a small LV cavity size is associated with functional limitation and history of syncope in HC.

Identification of viable myocardium in patients with chronic coronary artery disease using rest-redistribution thallium-201 tomography: optimal image analysis

With the widely used 50% threshold, sensitivity is high, but specificity is low in detecting viable myocardium on 201Tl SPECT. In this study, we sought to identify the best threshold for semiquantitative 201Tl analysis.

METHODS

Rest-redistribution 201Tl SPECT was performed in 46 patients with chronic coronary artery disease before and after myocardial revascularization. Regional function was evaluated by two-dimensional echocardiography before and after myocardial revascularization using a 3-point scale (1 = normal, 2 = hypokinetic, 3 = a/dyskinetic). Myocardial segments with abnormal systolic function were defined as viable if the systolic function score decreased > or = 1 after myocardial revascularization. A second group of 12 patients with chronic coronary artery disease constituted the validation population. Sensitivity-specificity curves, as well as receiver operating characteristic curves, for rest and redistribution mages were generated by varying the 201Tl uptake threshold.

RESULTS

A 65% threshold uptake using resting images was found to be the best for detecting a/dyskinetic segments that improve after myocardial revascularization from those that do not improve. Sensitivity was lower with a 65% threshold (75%) than with a 50% threshold (90%, p < 0.05), but specificity was higher (76% versus 26%, p < 0.05) resulting in better accuracy (76% versus 57%, p < 0.05) and positive predictive value (77% versus 55%), while the negative predictive value was not different (69% versus 75%, p not significant). The area under the receiver operating characteristic curve was significantly (p < 005) larger for rest (0.80 +/- 0.05) as opposed to redistribution (0.72 +/- 0.05) images. Similar results were obtained in a subgroup of patients with low ejection fraction. Significant correlations between the percentage of revascularized viable segments and both the change in ejection fraction and in postrevascularization ejection fraction were found. When these findings were applied in the validation group, a gain in specificity, accuracy and positive predictive value was obtained with the 65% threshold compared with the 50% threshold.

CONCLUSION

This study demonstrated that analysis of resting images and use of the 65% 201Tl uptake threshold is preferable for separating viable from not viable dyssynergic myocardial segments in patients with chronic coronary artery disease.

Pattern of left ventricular filling in hypertrophic cardiomyopathy. Assessment by Doppler echocardiography and radionuclide angiography

AIMS

The left ventricle in hypertrophic cardiomyopathy is anatomically and functionally non-uniform. This study was undertaken to verify whether a heterogeneity in the pattern of diastolic filling can be detected along the left ventricular inflow tract in hypertrophic cardiomyopathy.

METHODS AND RESULTS

Early (E) and late (A) diastolic velocities were recorded by Doppler echocardiography at mitral and at mid-ventricular level in 16 normal volunteers and 30 patients with hypertrophic cardiomyopathy. Patients with hypertrophic cardiomyopathy also underwent radionuclide angiography to assess left ventricular function. E wave decreased significantly in normal volunteers (80 +/- 15 to 60 +/- 14 cm x s(-1); P<0.001), but it increased in hypertrophic cardiomyopathy (76 +/- 22 to 87 +/- 28 cm x s(-1) P=0.04), whereas the A wave decreased similarly in both. By multivariate analysis, systolic asynchrony and the ejection fraction of left ventricular lateral wall were directly related to the pattern of early filling progression (r=0.656, F=9.467; P<0.002). Moreover, systolic asynchrony showed a univariate direct correlation with changes in E velocity (r=0.42; P=0.02).

CONCLUSION

Many patients with hypertrophic cardiomyopathy have an acceleration of filling within the left ventricular inflow tract; this phenomenon is directly related to systolic asynchrony and ejection fraction of the left ventricular lateral wall, suggesting increased suction.