Aortic biomechanics in hypertrophic cardiomyopathy.

BACKGROUND: Ventricular-vascular coupling is an important phenomenon in many cardiovascular diseases. The association between aortic mechanical dysfunction and left ventricular (LV) dysfunction is well characterized in many disease entities, but no data are available on how these changes are related in hypertrophic cardiomyopathy (HCM). AIM OF THE WORK: This study examined whether HCM alone is associated with an impaired aortic mechanical function in patients without cardiovascular risk factors and the relation of these changes, if any, to LV deformation and cardiac phenotype. METHODS: 141 patients with HCM were recruited and compared to 66 age- and sex-matched healthy subjects as control group. Pulse pressure, aortic strain, stiffness and distensibility were calculated from the aortic diameters measured by M-mode echocardiography and blood pressure obtained by sphygmomanometer. Aortic wall systolic and diastolic velocities were measured using pulsed wave Doppler tissue imaging (DTI). Cardiac assessment included geometric parameters and myocardial deformation (strain and strain rate) and mechanical dyssynchrony. RESULTS: The pulsatile change in the aortic diameter, distensibility and aortic wall systolic velocity (AWS') were significantly decreased and aortic stiffness index was increased in HCM compared to control (P < .001) In HCM AWS' was inversely correlated to age(r = - .32, P < .0001), MWT (r = - .22, P < .008), LVMI (r = - .20, P < .02), E/Ea (r = - .16, P < .03) LVOT gradient (r = - 19, P < .02) and severity of mitral regurg (r = - .18, P < .03) but not to the concealed LV deformation abnormalities or mechanical dyssynchrony. On multivariate analysis, the key determinant of aortic stiffness was LV mass index and LVOT obstruction while the role LV dysfunction in aortic stiffness is not evident in this population. CONCLUSION: HCM is associated with abnormal aortic mechanical properties. The severity of cardiac phenotype, not LV deformation, is interrelated to aortic stiffness in patients with HCM. The increased aortic stiffness seems to be promising module that can be added as clinical risk parameter in HCM.

Characterization of Left Atrial Mechanics in Hypertrophic Cardiomyopathy and Essential Hypertension Using Vector Velocity Imaging.

BACKGROUND: Systemic hypertension (HTN) and hypertrophic cardiomyopathy (HCM) may be associated with left atrial (LA) dilation, but whether LA functional abnormalities are characteristic to each disease or not, is unknown. The aim of this study was to characterize LA mechanical changes in patients with HTN and HCM using vector velocity imaging (VVI). METHODS: VVI-derived longitudinal LA function was acquired from apical views in 76 CM patients, 33 hypertension patients and 30 age-matched controls. Peak atrial longitudinal strain (ɛsys ), atrial strain rate during systole (SRsys ), early diastole (SRe ), and late diastole (SRa ) were measured (corresponding to LA reservoir, conduit and contractile functions, respectively). Similar parameters were used to assess left ventricular (LV) function. RESULTS: LV mass and LA volume index were higher in HCM and HTN than in controls. Both LA Reservoir function (LA ɛsys SRsys ) and conduit function (SRe ) were more declined in HCM patients, in comparison to HTN patients and controls (P < 0.0001),whereas conduit function was the only function deteriorated in the HTN group. LA contractile function was preserved among patient groups. In HCM, LV ɛsys and SRa [P < 0.001] are independent predictors for LA ɛsys . While in hypertension, only LVMI is an independent predictor for LA dysfunction (P < 0.01). By receiver operating characteristic analyses, only atrial reservoir function was extrapolative and appeared to be accurate in discriminating HCM from both hypertension and controls, with LA ɛsys ≤ 33% being more sensitive (71.8%) and specific (75%). CONCLUSIONS: Response of LA mechanics to pathologic hypertrophy is entirely different. In HCM LA reservoir and conduit functions are more deteriorated and related to the severity of phenotype, while in hypertension the conduit function is chiefly affected and LA dysfunction is linked to a more advanced disease.

Systolic function reserve using two-dimensional strain imaging in hypertrophic cardiomyopathy: comparison with essential hypertension.

BACKGROUND: Although patients with hypertrophic cardiomyopathy (HCM) have normal ejection fractions at rest, the investigators hypothesized that these patients have differentially abnormal systolic function reserves, limiting their exercise capacity compared with patients with hypertension (HTN). METHODS: Forty patients with HCM (mean age, 39.1 ± 12 years), 20 patients with HTN with LVH, and 33 healthy individuals underwent resting and peak exercise echocardiography using two-dimensional strain imaging. Peak longitudinal systolic strain (εsys) and strain rate were measured in apical views. Circumferential εsys and left ventricular (LV) twist were analyzed from short-axis views. LV systolic dyssynchrony was measured from regional longitudinal strain curves as the standard deviation of time to peak strain (time from the beginning of the Q wave on electrocardiography to peak εsys) between 12 segments. The differences between resting and peak exercise values were analyzed, and functional reserve was calculated as the difference divided by the resting value. RESULTS: In patients with HCM, resting values for longitudinal εsys, systolic strain rate, early diastolic strain rate, and atrial diastolic strain rate were significantly lower, while circumferential εsys and twist were higher, compared with patients with HTN and controls (P < .0001). Functional systolic reserve increased during exercise in controls (17 ± 6%), increased to a lesser extent in patients with HTN (10 ± 16%), and was markedly attenuated in patients with HCM (-23 ± 28%) (P < .001). At peak exercise, even with augmented circumferential εsys and twist in patients with HCM (P < .01) compared with those with HTN, both remained lower than in controls (P < .001). LV dyssynchrony was amplified during exercise in patients with HCM compared with those with HTN (P < .001). Within the entire population, exercise capacity was clearly correlated with systolic functional reserve. However when taken separately, it was mainly related to resting LV dyssynchrony and diastolic function in patients with HCM, whereas it was linked to age and LV wall thickness in those with HTN. CONCLUSIONS: Patients with HCM have significantly limited systolic function reserve and more dynamic dyssynchrony with exercise compared with those with HTN. Two-dimensional strain imaging during stress may provide a new and reliable method to identify patients at higher cardiovascular risk.

Relationship of mechanical dyssynchrony to QT interval prolongation in hypertrophic cardiomyopathy.

AIMS: Hypertrophic cardiomyopathy (HCM) is usually associated with electrocardiographic (ECG) abnormalities. QT interval and its dispersion can be clinical markers of electrophysiological instability and ventricular arrhythmias. We aimed to clarify the relation of QT variables to mechanical dyssynchrony and myocardial function in HCM. METHODS AND RESULTS: The study population comprised 82 HCM patients, 28 healthy subjects as control. We assessed regional deformation indexes using vector velocity imaging in 12 myocardial segments. Peak systolic strain (ε(sys)), strain rate (SR(sys)), and post-systolic strain (PSS) were measured. Contraction time (CT) was measured from regional strain curves for each segment, as the time from the beginning of the Q-wave to the time-to-peak ε(sys) (TPS), mechanical dyssynchrony was estimated as TPS-SD. From 12-lead surface ECG, QT interval, QT dispersion, and its corrected values were measured. According to QT(c) (QT(c) ≥ 440 or <440 ms), patients were categorized into two groups: long QT and normal QT HCM. In the long QT group, QT(cd) and CT in all left ventricular (LV) segments were significantly prolonged; ε(sys) and SR(sys) were markedly attenuated compared with the other two groups (P<0.001). LV dyssynchrony was significantly greater (P<0.001) and PSS was more frequent in long QT HCM compared with the other two groups (P<0.001). TPS-SD was correlated positively with QT(c) (r=0.38, P<0.01) and QT(cd) (r=0.45, P<0.001). QT(c) ≥ 440 ms identified LV mechanical dyssynchrony with 70% sensitivity, 100% specificity, and positive predictive value. CONCLUSION: QT interval prolongation on surface ECG shows significant association with mechanical dyssynchrony and LV dysfunction in HCM. This may add pathophysiological insight into understanding ECG changes in such myocardial disease.

Age-related alteration of risk profile, inflammatory response, and angiographic findings in patients with acute coronary syndrome.

BACKGROUND: Coronary artery disease (CAD) is a major public health problem which in turn imposes a significant burden on health care systems because of high morbidity and mortality. Although the multifactorial etiology of CAD increases with age, but in recent years, the incidence is increasing among younger age groups. OBJECTIVES: In this study we aimed to evaluate the effect of age on risk profile, inflammatory response and the angiographic findings in patients with ACS. PATIENTS AND METHODS: The study comprised 253 ACS patients. Seventy six (30%) with UA, 56 (22%) with NSTEMI and 121(48%) with STEMI diagnosis. The value of Hs-CRP, lipid profile, cardiac enzymes, risk factors, EF% and angiographic score were analyzed and compared in different age groups. RESULTS: Group 1 (n = 68) with age <45 years, group II (n = 110) with age >/=45-<65 years and group III (n = 75) >/=65 years. Group I had more prevalence of male sex, smoking, family history, hypertriglyceridemia and low levels of HDL (P < 0.01), higher incidence of STEMI (P < 0.01) and lower prevalence of UA (P < 0.01). Diabetes mellitus, hypertension, and female gender were more common in older groups. Hs-CRP was significantly lower in the young age (group I). Group I showed a preponderance of single-vessel disease, lower coronary atherosclerotic score and prevalent left anterior descending artery (LAD) involvement compared with older age groups. Hs-CRP was positively correlated to severity of CAD only in older groups. Stepwise multiple regression analysis showed that age, male gender, cardiac enzymes and EF% were common predictors of multivessel disease. Smoking was independent predictor in young patients <45 years while diabetes and Hs-CRP was the key predictor in older patient groups. CONCLUSION: Young patients with ACS had different clinical, angiographic and biochemical profile. Hs-CRP peak concentration did not correlate with angiographic findings in young patients that could be attributed to different risk profile and discrete underlying mechanism.

Tissue velocity imaging with dobutamine stress echocardiography--a quantitative technique for identification of coronary artery disease in patients with left bundle branch block.

BACKGROUND: Patients with left bundle branch block (LBBB) exhibit abnormal septal motion that may limit the interpretation of stress echocardiograms and persuade the results of myocardial scintigraphy. OBJECTIVES: We sought to analyze whether the use of tissue velocity imaging during graded dobutamine infusion is useful to identify and predict coronary artery disease (CAD) in patients with complete LBBB. METHODS: In all, 62 patients with LBBB (mean age 62 years, 34 men) with suggested CAD underwent dobutamine stress-tissue Doppler echocardiography within 6 weeks before coronary arteriography. Dobutamine infusion started at 5 micro/kg/min and increased up to 40 micro/kg/min with additional atropine during submaximal heart rate responses. In addition to wall-motion analysis, pulsed wave tissue Doppler sampling of mitral annulus at 5 corners was performed at rest in the apical 4-chamber plus aorta and 2-chamber apical views. The measurements were repeated at low dose (10-15 micro/kg/min) and at peak stress. Tissue Doppler echocardiography measurements included early peak systolic velocity (PSV), postsystolic shortening (PSS) velocity, peak early diastolic velocity (Ve), and peak late diastolic velocity. The results were compared with 20 healthy subjects as a control group. Patients were classified into two groups according to angiographic results: LBBB with CAD (n = 32) and LBBB without CAD (n = 30). RESULTS: There was no significant difference between LBBB groups in global wall-motion score index at rest; the delta changes in each group were almost similar during peak stress test (P > .05). In the LBBB with CAD group, PSV increased during peak stress to a smaller extent (6.3 +/- 1.1-7.2 +/- 2.0 cm/s, approximately 24% P < .03) than in non-CAD group (6.8 +/- 1.0-9.6 +/- 2.7 cm/s, approximately 46% P < .01). Similarly, Ve increased to a lesser extent in CAD group (deltaVe 1.6 +/- 1.7 vs 2.8 +/- 1.7 cm/s, approximately 25% vs 42% P < .0001). There were no significant difference in delta late diastolic velocity between LBBB and control groups or between each of them. PSS could be recorded at rest in 24 of 32 patients (75%) in CAD group and 17 of 30 patients (57%) in non-CAD group. In LBBB with CAD group, PSS was developed and significantly augmented from 4.7 +/- 3.1 to 6.3 +/- 3.4 cm/s (P < .001) during stress. Increment less than 2.5 cm/s in PSV and Ve during peak stress identified CAD with 88% sensitivity (for each) and 90% and 87% specificity, respectively. The cut-off values of PSS velocity greater than 4 cm/s at peak stress have strong diagnostic power for prediction of obstructive CAD in patients with LBBB (82% accuracy). CONCLUSION: Tissue Doppler echocardiography with dobutamine stress allows a diagnostic benefit in the detection of CAD in patients with LBBB. The magnitude of change of PSV and Ve in addition to PSS are quantitative parameters to identify CAD in patients with LBBB where subjective wall-motion analysis failed.

Mitral annular motion as a surrogate for left ventricular function: correlation with brain natriuretic peptide levels.

BACKGROUND: Pulsed-wave (PW) Doppler tissue velocities of the mitral annulus correlate well with Left Ventricular (LV) diastolic(D) and systolic(S) functions. Brain natriuretic peptide (BNP) levels have been shown to be elevated in patients with symptomatic LV dysfunction (Dys) and correlate to the severity of symptoms and prognosis. OBJECTIVES: To validate the accuracy of mitral annular motion (MAM) assessed by Doppler Tissue Imaging (DTI) & M-mode Echocardiography (MME) as a surrogate for determination of LV function in comparison with BNP. METHODS: A series of 133 patients with a variety of cardiac pathologies referred for echocardiography and 20 healthy age & sex matched volunteers as a control group were included the study. Ejection fraction (EF) of LV, Doppler recordings of the mitral inflow, MME and PWDTI data (from each of 4 mitral annular sites, inferior, anterior, septum and lateral) were obtained. Mean peak (S) MAM velocity (Sm), mean annular early (D) velocity (Em) by PWDTI and mean mitral annular plane (S) excursion (MAPSE) by MME were calculated by averaging of values measured at each annular site. BNP levels were measured by a rapid immunoassay and blinded to cardiologist making the assessment of LV function. RESULTS: MAPSE < 12 mm determined by MME has 90% sensitivity, 88% specificity & 89% accuracy for detection of LVEF <50%, while these values were 94%, 93% & 94% respectively for (Sm) < 8 cm/s determined by PWDTI. BNP level>75 pg/ml has 98% sensitivity, 90% specificity & 97% accuracy for detection of LV Dys either (S,D, or both). BNP levels were significantly higher in patients with combined (S & D) Dys. Than those with only (S) Dys, the later group had significantly higher BNP levels than those with only (D) Dys. (1054.5 +/- 202.3 pg/ml vs. 500 +/- 39.9 pg/ml & 500 +/- 39.9 pg/ml vs. 215.3 +/- 100.9 pg/ml respectively, P < 0.001) & each were significantly higher than control group (12.3 +/- 5.7 pg/ml, P < 0.001). Significant correlations (P < 0.001 for all) were found between BNP levels and Em (r =-0.82), Sm (r=-0.7), early transmitral (E) to Em ratio (r=0.61), MAPSE (r=-0.54), LVEF(r=-0.64) & LV end D dimension (r=0.63). CONCLUSION: MME and PWDTI used for assessment of MAM are useful methods for evaluation of LV function but parameters measured by PWDTI correlate more strongly with plasma BNP levels than those measured by MME and provide a simple, sensitive, accurate and reproducible tool for early diagnosis of LV dysfunction.