Substrate and procedural predictors of outcomes after catheter ablation for atrial fibrillation in patients with hypertrophic cardiomyopathy

Background: Hypertrophic cardiomyopathy (HCM) is often accompanied by atrial fibrillation (AF) due to diastolic dysfunction, elevated left atrial pressure, and enlargement. Although catheter ablation for drug‐refractory AF is an effective treatment, the efficacy in HCM remains to be established. Methods: Thirty‐three consecutive patients (25 male, age 51 ± 11 years) with HCM underwent pulmonary vein (PV) isolation (n = 8) or wide area circumferential ablation with additional linear ablation (n = 25) for drug‐refractory AF. Twelve‐lead and 24‐hour ambulating ECGs, echocardiograms, event monitor strips, and SF 36 quality of life (QOL) surveys were obtained before ablation and for routine follow‐up. Results: Twenty‐one (64%) patients had paroxysmal AF and 12 (36%) had persistent/permanent AF for 6.2 ± 5.2 years. The average ejection fraction was 0.63 ± 0.12. The average left atrial volume index was 70 ± 24 mL/m 2 . Over a follow‐up of 1.5 ± 1.2 years, 1‐year survival with AF elimination was 62%(Confidence Interval [CI]: 66‐84) and with AF control was 75%(CI: 66‐84). AF control was less likely in patients with a persistent/chronic AF, larger left atrial volumes, and more advanced diastolic disease. Additional linear ablation may improve outcomes in patient with severe left atrial enlargement and more advanced diastolic dysfunction. Two patients had a periprocedureal TIA, one PV stenosis, and one died after mitral valve replacement from prosthetic valve thrombosis. QOL scores improved from baseline at 3 and 12 months. Conclusion: Outcomes after AF ablation in patients with HCM are favorable. Diastolic dysfunction, left atrial enlargement, and AF subtype influence outcomes. Future studies of rhythm management approaches in HCM patients are required to clarify the optimal clinical approach.     

Effects of isometric exercise and heart rate on left ventricular filling pattern assessed by pulsed Doppler echocardiography

Left ventricular filling pattern was assessed by pulsed Doppler echocardiography at rest and during handgrip exercise in 33 healthy middle-aged subjects. The peak mitral flow-velocities during the early rapid filling phase (E) and during late (atrial) filling (A) were measured and the ratio of these peak flow-velocities (E:A ratio) was calculated. The E:A ratio was inversely related to age (r = -0.50), heart rate (r = -0.47) and septal thickness (r = -0.36) at rest. Exercise caused a significant (P less than 0.001) decrease in E:A ratio as a result of an increase in the peak A velocity. No significant change in the peak E velocity was observed during exercise. The exercise E:A ratio was related to heart rate (r = -0.53), but not to resting E:A ratio or age, since the decrease in E:A ratio tended to be less in the older subjects. Our study shows that isometric exercise augments the relative contribution of atrial contraction of left ventricular filling and this increase may 'mask' minor changes in resting transmitral flow pattern associated with, e.g. ageing. Secondly, in addition to age, heart rate must be taken into account when studying populations with different heart-rate levels or interventions associated with simultaneous heart rate changes.     

Beta-blocker infusion did not improve left ventricular diastolic function in myocardial infarction: A doppler echocardiography and cardiac catheterization study

Left ventricular (LV) diastolic function changes after myocardial infarction. It has been suggested that beta blockers may improve diastolic function in hypertensive and heart failure patients. Doppler echocardiographic filling patterns and invasive hemodynamic indices have been used to analyze LV diastolic function. To determine the effect of beta blockers on LV diastolic function, we studied 32 patients with anterior wall myocardial infarction with a mean age of 53 years. Peak early and late flow velocities, peak early-to-late flow velocities ratio, pressure half time, diastolic filling period, isovolumic relaxation time, cardiac index, mean arterial pressure, wedge pressure, and systemic and pulmonary vascular resistance indices were obtained simultaneously before and after an intravenous infusion of 10 mg of atenolol. Cardiac index decreased from 4.27 ± 0.97 to 3.19 ± 0.911/min/m² (p=0.0001); mean arterial pressure decreased from 85 ± 10 to 80 ± 11 mmHg (p=0.004); wedge pressure increased from 11 ± 5 to 13 ± 4 rnmHg (p = 0.002); systemic vascular resistance index increased from 1586 ± 409 to 1980 ± 634 dynm²s/cm⁵ (p = 0.0002); pulmonary vascular resistance index increased from 115 ± 58 to 163 ± 72 dynm²s/cm⁵ (p = 0.0004); peak late flow velocity decreased from 64 ± 15 to 49 ± 14 cm/s (p = 0.0001); early-to-late ratio increased from 0.95 ± 0.35 to 1.29 ± 0.36 (p = 0.0001); diastolic filling period increased from 300 ± 108 to 400 ± 110 ms (p=0.0001) and isovolumic relaxation time increased from 133 ± 29 to 143 ± 29 ms (p = 0.009). No significant changes were observed for peak early flow velocity and pressure half-time. Multivariate regression analysis suggests that significant changes observed on Doppler echocardiographic parameters can be attributed in part to beta-blocker effect on heart rate analyzed as diastolic filling period. We concluded that beta-blocker infusion changes LV diastolic function analyzed by Doppler echocardiography in patients with anterior wall myocardial infarction. Moreover, the increase observed on wedge pressure suggests deterioration in cardiac function.     

高频超声评价阿托伐他汀对高胆固醇血症动脉内皮功能的影响

目的评价新型调脂药物阿托伐他汀对高胆固醇血症内皮功能的影响。方法高胆固醇血症组采用阿托伐他汀降脂治疗 ,于治疗前和治疗 8周后利用高分辨率超声仪评价肱动脉内皮依赖性舒张功能的变化 ,并与正常对照组进行比较。结果高胆固醇血症组患者内皮依赖舒张功能 (EDD)明显受损 (4 .8± 1.9) % ,与对照组 (12 .2± 3 .4) %比较 ,有显著性差异 (P<0 .0 1)。阿托伐他汀治疗 8周后 ,内皮功能明显改善 [(10 .3± 2 .5 ) % ] ,与治疗前 [(4 .8± 1.9) % ]比较 ,有显著性差异 (P<0 .0 1) ;与正常对照组 [(12 .2± 3 .4) % ]比较 ,无显著性差异 (P>0 .0 5 )。结论高胆固醇血症患者内皮依赖舒张功能明显减退 ,阿托伐他汀可有效降低血脂 ,恢复内皮功能。高频血管超声能准确、可靠地检测出血管内皮依赖舒张功能的损害 ,并可用于评价药物治疗对内皮功能的影响     

Left Atrial Strain for Assessment of Left Ventricular Diastolic Function: Focus on Populations With Normal LVEF

Left atrial (LA) strain has emerged as a useful parameter for the assessment of left ventricular (LV) diastolic function and the estimation of LV filling pressures. Some have advocated using LA strain by itself, mainly reservoir strain, as a single stand-alone measurement for this objective. Recent data indicate several challenges for this application in patients with normal left ventricular ejection fraction (LVEF) because of the wide range for normal values and the load dependency of LA strain. Both findings can result in reduced left atrial reservoir strain (LARS) values in normal subjects that overlap those seen in patients with diastolic dysfunction. LARS for the estimation of LV filling pressures is most accurate in patients with depressed LVEF. It is less accurate in patients with normal ejection fraction. In this group of patients, LARS <18% has high specificity for increased LV filling pressures. There are promising data showing the association of LARS with outcome events in patients with normal ejection fraction, and additional data are needed to confirm that it provides incremental information over clinical and other echocardiographic measurements.     

Relation of Left Ventricular Diastolic Function to Global Fibrosis Burden: Implications for Heart Failure Risk Stratification

BackgroundLeft ventricular (LV) diastolic function is primarily assessed by means of echocardiography, which has limited utility in detecting fibrosis. Cardiac magnetic resonance (CMR) readily detects and quantifies fibrosis.ObjectivesIn this study, the authors sought to determine the association of LV diastolic function by echocardiography with CMR-determined global fibrosis burden and the incremental value of fibrosis with diastolic function grade in prediction of total mortality and heart failure hospitalizations.MethodsA total of 549 patients underwent comprehensive echocardiography and CMR within 30 days. Echocardiography was used to assess LV diastolic function, and CMR was used to determine LV volumes, mass, ejection fraction, replacement fibrosis, and percentage extracellular volume fraction (ECV).ResultsNormal diastolic function was present in 142 patients; the rest had diastolic dysfunction grades I to III, except for 18 (3.3%) with indeterminate results. The event rate was higher in patients with diastolic dysfunction compared with patients with normal diastolic function (33.4% vs 15.5; P < 0.001). The model including LV diastolic function grades II and III predicted composite outcome (C-statistic: 0.71; 95% CI: 0.67-0.76), which increased by adding global fibrosis burden (C-statistic: 0.74, 95% CI: 0.70-0.78; P = 0.02). For heart failure hospitalizations, the competing risk model with LV diastolic function grades II and III was good (C-statistic: 0.78; 95% CI: 0.74-0.83) and increased significantly with the addition of global fibrosis burden (C-statistic: 0.80; 95% CI: 0.76-0.85; P = 0.03).ConclusionsHigher grades of diastolic dysfunction are seen in patients with replacement fibrosis and increased ECV. Fibrosis burden as determined with the use of CMR provides incremental prognostic information to echocardiographic evaluation of LV diastolic function.