Biventricular pacing improves cardiac function and prevents further left atrial remodeling in patients with symptomatic atrial fibrillation after atrioventricular node ablation.

BACKGROUND: Randomized trials have demonstrated benefits of biventricular (BiV) pacing in patients with advanced heart failure, intraventricular conduction delay, and atrial fibrillation (AF) post-atrioventricular (AV) node ablation. The AV Node Ablation with CLS and CRT Pacing Therapies for Treatment of AF trial (AVAIL CLS/CRT) was designed to demonstrate superiority of BiV pacing in patients with AF after AV node ablation, to evaluate its effects on cardiac structure and function, and to investigate additional benefits of Closed Loop Stimulation (CLS) (BIOTRONIK, Berlin, Germany). METHODS: Patients with refractory AF underwent AV node ablation and were randomized (2:2:1) to BiV pacing with CLS, BiV pacing with accelerometer, or right ventricular (RV) pacing. Echocardiography was performed at baseline and 6 months, with paired data available for 108 patients. RESULTS: The RV pacing contributed to significant increase in left atrial volume, left ventricular (LV) end-systolic volume, and LV mass compared to BiV pacing. Ejection fraction decreased insignificantly with RV pacing compared to significant increase with BiV pacing. Interventricular dyssynchrony significantly decreased with BiV compared with RV pacing. Closed Loop Stimulation did not result in additional echocardiographic changes; heart rate distribution was significantly wider with CLS. All groups showed significant improvement in 6-minute walk distance, quality-of-life score, and New York Heart Association class. CONCLUSION: In conclusion, RV pacing results in significant increase in left atrial volume, LV mass, and worsening of LV contractility compared to patients receiving BiV pacing post-AV node ablation for refractory AF. Closed Loop Stimulation was not associated with additional structural changes but resulted in significantly wider heart rate distribution.

Endothelial function and urine albumin levels among asymptomatic Mexican-Americans and non-Hispanic whites.

BACKGROUND: Mexican-Americans (MA) exhibit increases in various cardiovascular disease (CVD) risk factors compared to non-Hispanic Whites (NHW), yet are reported to have lower CVD mortality rates. Our aim was to help explain this apparent paradox by evaluating endothelial function and urine albumin levels in MA and NHW. METHODS: One hundred-five MA and 100 NHW adults were studied by brachial artery flow-mediated dilatation (FMD), blood and urine tests. Participants were studied by ultrasound-determined brachial artery flow-mediated dilatation (FMD), blood and urine tests, at a single visit. RESULTS: Despite higher BMI and triglycerides in MA, MA demonstrated higher FMD than did NHW (9.1 +/- 7.3% vs. 7.1 +/- 6.3%, p < 0.04). Among MA, urinary albumin was consistently lower in participants with FMD >or= 7% FMD versus < 7% FMD (p < 0.006). In multivariate analyses in MA men, urinary albumin was inversely related to FMD (r = -0.26, p < 0.05), as were BMI and systolic blood pressure. In MA women, urinary albumin:creatinine ratio was an independent inverse predictor of FMD (p < 0.05 ). CONCLUSION: To our knowledge, this is the first study to analyze, in asymptomatic adults, the relation of MA and NHW ethnicity to FMD and urine albumin levels. The findings confirm ethnic differences in these important subclinical CVD measures.

Usefulness of carotid ultrasound to improve the ability of stress testing to predict coronary artery disease.

Carotid ultrasound is a useful tool to detect plaque and measure carotid intimal-medial thickness (CIMT), which help identify asymptomatic patients at risk of cardiovascular events. However, the role of carotid ultrasound in stratifying risk in symptomatic patients has not been studied. We prospectively examined the hypothesis that in symptomatic patients undergoing exercise (or pharmacologic) stress testing (EST), CIMT and carotid plaque will improve the ability to identify patients with > or =50% coronary diameter stenosis. Mean and maximal CIMTs were measured in 50 symptomatic patients without known coronary artery disease (CAD) who were scheduled to undergo diagnostic angiography after EST with imaging. Pretest probability of CAD was calculated for each patient based on age, gender, and nature of symptoms. Fifty percent of patients were men, 32% were diabetic, 70% had hypertension, and 58% had dyslipidemia. CAD > or =50% was associated with CIMT in the >75th percentile (74% vs 44%, p = 0.047) and with presence of carotid plaque (96% vs 59%, p = 0.003). Of patients with an equivocal/negative EST result (n = 38), those with carotid plaque had a 46% (13 of 28) prevalence of significant CAD; in the smaller subset of patients without carotid plaque (n = 10), none had luminal stenosis > or =50% (p = 0.007). Pretest probability of CAD, presence of carotid plaque, moderately/severely abnormal EST result, and hypertension were independent predictors of significant CAD. In conclusion, carotid ultrasound appears to offer incremental value to EST in predicting presence or absence of > or =50% coronary diameter stenosis in symptomatic patients with equivocal/negative EST result.

What parameters affect left ventricular diastolic flow propagation velocity? In vitro studies using color M-mode Doppler echocardiography.

BACKGROUND: Insufficient data describe the relationship of hemodynamic parameters to left ventricular (LV) diastolic flow propagation velocity (Vp) measured using color M-mode Doppler echocardiography. METHODS: An in vitro LV model used to simulate LV diastolic inflow with Vp measured under conditions of varying: 1) Stroke volume, 2) heart rate (HR), 3) LV volume, 4) LV compliance, and 5) transmitral flow (TMF) waveforms (Type 1: constant low diastasis flow and Type 2: no diastasis flow). RESULTS: Univariate analysis revealed excellent correlations of Vp with stroke volume (r = 0.98), LV compliance (r = 0.94), and HR with Type 1 TMF (r = 0.97). However, with Type 2 TMF, HR was not associated with Vp. LV volume was not related to Vp under low compliance, but inversely related to Vp under high compliance conditions (r = -0.56). CONCLUSION: These in vitro findings may help elucidate the relationship of hemodynamic parameters to early diastolic LV filling.

Which echocardiographic Doppler left ventricular diastolic function measurements are most feasible in the clinical echocardiographic laboratory?

Numerous measures of left ventricular diastolic function are currently in clinical use. To determine which echo-Doppler left ventricular diastolic function measurements are most feasible in the clinical echocardiographic laboratory, the success rate, recording time taken by the sonographer, and inter-reader variability were calculated for transmitral valve inflow, pulmonary vein flow, tissue Doppler imaging, and color M-mode flow propagation velocity in 80 inpatients.

Usefulness of Doppler echocardiographic left ventricular diastolic function and peak exercise oxygen consumption to predict cardiovascular outcomes in patients with systolic heart failure (from HF-ACTION).

Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training (HF-ACTION) was a multicenter, randomized controlled trial designed to examine the safety and efficacy of aerobic exercise training versus usual care in 2,331 patients with systolic heart failure (HF). In HF-ACTION patients with rest transthoracic echocardiographic measurements, the predictive value of 8 Doppler echocardiographic measurements-left ventricular (LV) diastolic dimension, mass, systolic (ejection fraction) and diastolic (mitral valve peak early diastolic/peak late diastolic [E/A] ratio, peak mitral valve early diastolic velocity/tissue Doppler peak early diastolic myocardial velocity [E/E'] ratio, and deceleration time) function, left atrial dimension, and mitral regurgitation severity-was examined for a primary end point of all-cause death or hospitalization and a secondary end point of cardiovascular disease death or HF hospitalization. Also compared was the prognostic value of echocardiographic variables versus peak oxygen consumption (Vo(2)). Mitral valve E/A and E/E' ratios were more powerful independent predictors of clinical end points than the LV ejection fraction but less powerful than peak Vo(2). In multivariate analyses for predicting the primary end point, adding E/A ratio to a basic demographic and clinical model increased the C-index from 0.61 to 0.62, compared with 0.64 after adding peak Vo(2). For the secondary end point, 6 echocardiographic variables, but not the LV ejection fraction or left atrial dimension, provided independent predictive power over the basic model. The addition of E/E' or E/A to the basic model increased the C-index from 0.70 to 0.72 and 0.73, respectively (all p values <0.0001). Simultaneously adding E/A ratio and peak Vo(2) to the basic model increased the C-index to 0.75 (p <0.0005). No echocardiographic variable was significantly related to the change from baseline to 3 months in exercise peak Vo(2). In conclusion, the addition of echocardiographic LV diastolic function variables improves the prognostic value of a basic demographic and clinical model for cardiovascular disease outcomes.

Relation of metabolic syndrome components to left ventricular mass in Mexican Americans versus non-Hispanic whites.

Metabolic syndrome (MetS) is associated with increased risk for cardiovascular disease (CVD). Mexican Americans (MA) exhibit increases in CVD risk factors compared with non-Hispanic whites (NHW), but few data exist comparing the relation of MetS to subclinical CVD, for example, left ventricular (LV) mass. Asymptomatic subjects (104 MA and 101 NHW, 52.2% female, aged 48 ± 12 years) were studied by echocardiography (echo) and by blood and urine tests. Metabolic syndrome was defined based on the American Heart Association/National Heart, Lung, and Blood Institute definition. Echo LV mass was compared with the presence or absence of MetS and with the number of MetS components. Multiple linear regression also examined the association of MetS with LV mass adjusted for non-MetS risk factors. Left ventricular mass was lower in MA (145.5 ± 43.9 g) compared with NHW (160.2 ± 49.9 g) (P < .05), although this difference was attenuated after adjusting for MetS and other risk factors. Left ventricular mass was higher in those with vs without MetS in both MA and NHW men and women (P < .05 to P < .01). There was a significant (P < .001) graded increase in echo LV mass with increasing number of MetS components both in MA (108.3 to 153.8 g) and NHW (144.3 to 215.1 g). In multiple regression analysis, male sex and MetS remained independently associated (P < .0001) with LV mass; however, body mass index explained much of this association, indicating the strong association of obesity with LV mass. Mean LV mass in both MA and NHW adults was higher in those with vs without MetS and with increasing number of MetS components, with body mass index the principal component of MetS associated with LV mass. The prognostic significance of LV mass in persons with MetS requires further study.

Do differences in subclinical cardiovascular disease in mexican americans versus European americans help explain the Hispanic paradox?

Mexican Americans have exhibited increases in various coronary heart disease risk factors compared to European Americans but have also had reportedly lower coronary heart disease mortality from vital statistics studies. We hypothesized this apparent paradox might relate to lower levels of subclinical disease in Mexican Americans. A total of 105 adult Mexican Americans (42 men and 63 women, age 46 +/- 14 years) and 100 European Americans (59 men and 41 women, age 50 +/- 11 years) were studied using blood tests, transthoracic echocardiography, and computed tomography coronary artery calcium (CAC) scans. Despite a greater body mass index and triglycerides in Mexican Americans (p <0.001), the Mexican Americans demonstrated less subclinical disease than did the European Americans (14.4% vs 25.7% with CAC scores >0, p <0.05 and mean left ventricular mass [LV] of 146 vs 160 g, p <0.05). Also, the LV mass was significantly greater in Mexican Americans with than in those without CAC (mean 172 vs 140 g, p <0.05). On logistic regression analysis, age and diastolic blood pressure were associated with an increased likelihood of CAC (p <0.001 and p <0.01, respectively), and Mexican-American ethnicity was associated with a decreased likelihood of CAC (odds ratio 0.33, 95% confidence interval 0.12 to 0.87, p <0.05). On multiple regression analysis, male gender, body surface area, and systolic blood pressure were independently associated with an increased LV mass (all p <0.001). The body mass index was less strongly related to the LV mass than was the body surface area and was not related to CAC. In conclusion, Mexican-American ethnicity is associated with both a lower LV mass and a lower prevalence of CAC, although the differences in LV mass did not remain after adjustment for other factors. Although systolic blood pressure, body surface area, and male gender were most strongly associated with the LV mass, age and diastolic blood pressure, in addition to Mexican-American ethnicity, were the most important indicators of CAC.

Technical aspects of diastology: why mitral inflow and tissue Doppler imaging are the preferred parameters?

Doppler methods for assessing left ventricular (LV) diastolic function have increased in number and complexity. However, time constraints may prevent measurement of all parameters during routine transthoracic echocardiography. Therefore, we designed a study to determine which Doppler parameters could be most successfully and quickly obtained. The recording success rate and time required to record different LV diastolic function parameters were evaluated in 80 patients. A specific recording protocol was followed by an experienced, credentialed sonographer and time intervals to record each parameter were measured. In comparison with color Doppler M-mode of LV inflow propagation velocities (Vp) and pulmonary venous (PV) flow measurements, transmitral valve (MV) flow and tissue Doppler imaging (TDI) of the mitral annulus had the highest recording success rate and required the shortest time to record. PV flow and Vp took longer to obtain (80.1+/-34.3 sec and 57.1+/-29.1 sec, respectively) than did mitral valve inflow (36.3+/-20.7 sec) and mitral valve annular TDI (29.3+/-18.4 sec for septal and 33.3+/-14.5 sec for lateral). MV flow velocities, Vp, and TDI were successfully recorded in virtually all patients (99-100%). In comparison, the PV flow velocities and durations were successfully recorded less often. The range of success rates for the six PV flow parameters was 49-84%. Since MV flow and TDI also have been shown by us to have the lowest interreader variability, measurement of these two parameters may be preferred for routine clinical evaluation of LV diastolic function in a busy echocardiography laboratory.