Septal ablation in hypertrophic obstructive cardiomyopathy improves systolic myocardial function in the lateral (free wall): a follow-up study using CMR tissue tagging and 3D strain analysis

Aims: Alcohol septal ablation (ASA) has been successful in the treatment of symptomatic hypertrophic obstructive cardiomyopathy (HOCM). The aim of this study is to evaluate the effects of ethanol-induced myocardial infarcts on regional myocardial function using cardiac magnetic resonance (CMR) tissue tagging and 3-dimensional (3D) strain analysis. Methods and results: In nine patients (age 52±15 years) who underwent ASA, CMR was performed prior to and 6 months after the procedure. Regional myocardial mass was evaluated using cine imaging. Myocardial tagging was used to calculate systolic 3D myocardial strain values. These strain values were used to calculate the shortening index (SI), a robust parameter for myocardial contraction. Maximum end-systolic (ES) SI and systolic SI rate were quantified in three circumferential segments: septum, adjacent, and remote (lateral) myocardium. Compared with baseline, septal and non-septal mass decreased at follow-up (from 72±27 to 59±21 g; P=0.008 and from 131±34 to 109±30 g; P=0.008, respectively). In the septum, maximum ES SI and SI rate remained unchanged after ASA. In adjacent myocardium, ES SI remained unchanged, whereas SI rate improved (from -56.5±21.1 to -70.0±16.7%/s; P=0.02). Both ES SI and SI rate improved significantly in remote myocardium (from -16.9±2.8 to -18.8±3.2%; P=0.02 and from -70.3±9.2 to -86.1±15.0%/s; P=0.01, respectively). Conclusion: Reduction of left ventricular (LV) outflow tract obstruction in symptomatic HOCM is associated with a significant reduction in myocardial mass and improvement of intramural systolic function in the lateral (remote) wall, indicating reversed LV remodelling. © The European Society of Cardiology 2006. All rights reserved

Impact of alcohol septal ablation on left anterior descending coronary artery blood flow in hypertrophic obstructive cardiomyopathy

Objectives: The aim of this study was to evaluate the effects of alcohol septal ablation (ASA) on coronary blood flow in symptomatic hypertrophic obstructive cardiomyopathy (HOCM) using cardiac MR (CMR) coronary flow measurements. Background: CMR flow mapping enables quantification of coronary blood flow in a noninvasive way. Both left ventricular outflow tract (LVOT) gradient reduction and myocardial scarring after ASA are expected to influence left anterior descending (LAD) coronary blood flow. Methods: Cine, contrast-enhanced (CE) imaging and breath-hold CMR phase contrast velocity mapping were performed at baseline and 1 and 6 months after ASA in seven patients. Changes of coronary blood flow were related to left ventricular (LV) mass reduction, enzyme release, volume of ethanol administered, LVOT gradient reduction, and LV rate pressure product (LVRPP). Results: A significant mass reduction was observed bothin the target septal myocardium and in the total myocardium (both P < 0.01). Mean myoca

Functional outcome after revascularization in patients with chronic ischemic heart disease: a quantitative late gadolinium enhancement CMR study evaluating transmural scar extent, wall thickness and periprocedural necrosis

In patients with chronic ischemic myocardial dysfunction, late gadolinium enhancement CMR (LGE-CMR) accurately depicts the regional extent of fibrosis and predicts functional recovery after revascularization. We hypothesized that the predictive accuracy of LGE-CMR could be optimized by not only taking into account the transmural extent of hyperenhancement but also the amount of residual, non-enhanced viable myocardium, and procedure related necrosis. We studied 45 patients with chronic ischemic left ventricular dysfunction, who underwent cine and LGE-CMR 1 month before and 3 months after surgical or percutaneous revascularization. Segmental and global function, scar, presence of a significant residual viable rim (defined as ≥4.5 mm), and procedure related necrosis were fully quantified using standardized methods and objective thresholds. Sixty percent of segments without hyperenhancement showed functional improvement at follow-up. No improvement was observed in segments with > 75% segmental extent of hyperenhancement (SEH), while segments with 1-25%, 26-50%, and 51-75% SEH were 4, 8, and 20 times less likely to improve (multilevel analysis, p < 0.001). Thickness of the viable rim largely paralleled total wall thickness; therefore, the presence of a significant viable rim did not provide additional diagnostic value beyond SEH. Procedure related necrosis was found in 12 (27%) patients. The presence of procedure related necrosis was the only (negative) predictor of changes in left ventricular volumes and ejection fraction. In conclusion, we found that functional outcome after revascularization was influenced by both transmural extent of hyperenhancement and procedure related necrosis. However, the presence of a significant residual, viable rim was of no additional diagnostic value. Copyright © 2007 Informa Healthcare USA, Inc

Measurement of left ventricular volumes and function with O-15-labeled carbon monoxide gated positron emission tomography: comparison with magnetic resonance imaging

Background. Positron emission tomography (PET) with inhaled oxygen 15-labeled carbon monoxide (CO) is used as a marker of myocardial blood pool. Only a limited number of studies with small numbers of patients have reported on the assessment of left ventricular (LV) volumes by use of O-15-labeled CO. The aim of this study was to compare LV volumes and function as measured by routinely acquired blood pool images by use of gated O-15-labeled CO PET with the reference technique, cardiovascular magnetic resonance imaging (MRI). Methods and results. Thirty-four subjects with a varying degree of LV function were studied. LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), and LV ejection fraction (LVEF) were determined by both MRI and gated PET by use of O-15-labeled CO. Volumes were comparable with respect to LVEDV (196 ± 83 and 192 ± 91 mL, respectively; P = not significant). LVESV, however, was slightly overestimated by PET (119 ± 85 and 136 ± 94 mL, respectively; P < .05), resulting in a significant underestimation of LVEF (44% ± 19% and 35% ± 18%, respectively; P < .05). Observed correlations for LVEDV, LVESV, and LVEF were 0.90, 0.96, and 0.86, respectively (all P< .01). Conclusions. Gated O-15-labeled CO PET measurements of LVEDV, LVESV, and LVEF show good correlation with MRI over a wide range of LV volumes during routinely acquired blood pool images. LVEF, however, may be underestimated compared with MRI

Determinants of coronary microvascular dysfunction in symptomatic hypertrophic cardiomyopathy

Impaired hyperemic myocardial blood flow (MBF) in hypertrophic cardiomyopathy (HCM), despite normal epicardial coronary arteries, results in microvascular dysfunction. The aim of the present study was to determine the relative contribution of extravascular compressive forces to microvascular dysfunction in HCM. Eighteen patients with symptomatic HCM and normal coronary arteries and 10 age-matched healthy volunteers were studied with PET to quantify resting and hyperemic MBF at a subendocardial and subepicardial level. In HCM patients, MRI was performed to determine left ventricular (LV) mass index (LVMI) and volumes, echocardiography to assess diastolic perfusion time, heart catheterization to measure LV outflow tract gradient (LVOTG) and LV pressures, and serum NH2-terminal pro-brain natriuretic peptide (NT-proBNP) as a biochemical marker of LV wall stress. Hyperemic MBF was blunted in HCM vs. controls (2.26 ± 0.97 vs. 2.93 ± 0.64 ml·min-1·g-1, P < 0.05). In contrast to controls (1.38 ± 0.15 to 1.25 ± 0.19, P = not significant), the endocardial-to-epicardial MBF ratio decreased significantly in HCM during hyperemia (1.20 ± 0.11 to 0.88 ± 0.18, P < 0.01). This pattern was similar for hypertrophied septum and lateral wall. Hyperemic MBF was inversely correlated with LVOTG, NT-proBNP, left atrial volume index, and LVMI (all P < 0.01). Multivariate regression analysis, however, revealed that only LVMI and NT-proBNP were independently related to hyperemic MBF, with greater impact at the subendocardial myocardial layer. Hyperemic MBF is more severely impaired at the subendocardial level in HCM patients. The level of impairment is related to markers of increased hemodynamic LV loading conditions and LV mass. These observations suggest that, in addition to reduced capillary density caused by hypertrophy, extravascular compressive forces contribute to microvascular dysfunction in HCM patients. Copyrigh