Ethnicity and Left Ventricular Diastolic Function in Hypertension
Objectives: We investigated whether diastolic function differs between hypertensive patients of African-Caribbean or white European origin and established whether differences could be explained by confounding variables.
Background: African Caribbeans are known to have a higher prevalence of heart failure than white Europeans but it is unclear whether this is a result of known risk factors. Tissue Doppler technology now allows accurate quantification of diastolic function, which is recognized as an important factor in the development of heart failure.
Methods: Participants from a single center participating in the ASCOT (Anglo-Scandinavian Cardiac Outcomes Trial), composed of patients with hypertension but no evidence of heart failure, were studied. Left ventricular structure and function were measured in 509 patients using conventional and tissue Doppler echocardiography. Diastolic function was assessed using the tissue Doppler early diastolic velocity E' (averaged from 3 left ventricular segments) and the ratio of this and the transmitral early filling velocity E (E/E').
Results: In African-Caribbean patients, mean E' was significantly lower (7.7 cm/s vs. 8.6 cm/s, p = 0.003) and mean E/E' was significantly higher (8.85 vs. 7.93, p = 0.003). After adjustment for confounding variables–age, gender, systolic blood pressure, pulse pressure, cholesterol, smoking, ejection fraction, left ventricular mass index, and diabetes mellitus–the effect of African-Caribbean ethnicity on diastolic function remained highly significant (E': 7.52 vs. 8.51; p <0.001; E/E': 8.89 vs. 7.93; p = 0.003; African Caribbeans vs. white Europeans for both comparisons).
Conclusions: Diastolic function is significantly worse in hypertensive patients of African-Caribbean origin than in white Europeans. This difference in diastolic performance is not due to known confounding variables.
Persons of black African descent in the Western world (African Americans in the U.S. and African Caribbeans in the United Kingdom) have a greater risk of heart failure than comparator populations of white European origin. It is not known whether this cardiac dysfunction occurs because of an ethnic difference in myocardial susceptibility, or because of an increased prevalence of factors that contribute to ventricular dysfunction among African Caribbeans, such as left ventricular hypertrophy (LVH), type 2 diabetes mellitus, obesity, and high blood pressure (BP). In addition, interpretation of comparator studies performed in patients with established end organ failure is made more difficult by possible differential effects of complex treatment regimes. What is required is a study performed at an earlier stage of disease, with stratification or adjustment for risk factors.
The earliest cardiac consequence of hypertension is diastolic dysfunction, which is part of a continuum of ventricular impairment ending in systolic heart failure. However, until relatively recently it has been difficult to reliably quantify diastolic dysfunction.
The advent of tissue Doppler technology has provided a solution to some of the problems associated with traditional Doppler echocardiography. Rather than interpreting patterns of blood flow, it measures myocardial velocities directly and is more reproducible than historically used echocardiographic methods for assessing diastolic function, such as the Valsalva maneuver or pulmonary vein flow. It provides measures that are less affected by volume status or vasodilator drug therapy than are conventional techniques, and when combined with the transmitral early filling wave (E) to form a ratio (E/E'), provides an estimate of left atrial filling pressures.
In this study, tissue Doppler was used to investigate whether diastolic function differs between hypertensive persons of African-Caribbean origin and white Europeans, and whether any differences observed could be explained by potential confounding variables.
Abstract and Introduction
Abstract
Objectives: We investigated whether diastolic function differs between hypertensive patients of African-Caribbean or white European origin and established whether differences could be explained by confounding variables.
Background: African Caribbeans are known to have a higher prevalence of heart failure than white Europeans but it is unclear whether this is a result of known risk factors. Tissue Doppler technology now allows accurate quantification of diastolic function, which is recognized as an important factor in the development of heart failure.
Methods: Participants from a single center participating in the ASCOT (Anglo-Scandinavian Cardiac Outcomes Trial), composed of patients with hypertension but no evidence of heart failure, were studied. Left ventricular structure and function were measured in 509 patients using conventional and tissue Doppler echocardiography. Diastolic function was assessed using the tissue Doppler early diastolic velocity E' (averaged from 3 left ventricular segments) and the ratio of this and the transmitral early filling velocity E (E/E').
Results: In African-Caribbean patients, mean E' was significantly lower (7.7 cm/s vs. 8.6 cm/s, p = 0.003) and mean E/E' was significantly higher (8.85 vs. 7.93, p = 0.003). After adjustment for confounding variables–age, gender, systolic blood pressure, pulse pressure, cholesterol, smoking, ejection fraction, left ventricular mass index, and diabetes mellitus–the effect of African-Caribbean ethnicity on diastolic function remained highly significant (E': 7.52 vs. 8.51; p <0.001; E/E': 8.89 vs. 7.93; p = 0.003; African Caribbeans vs. white Europeans for both comparisons).
Conclusions: Diastolic function is significantly worse in hypertensive patients of African-Caribbean origin than in white Europeans. This difference in diastolic performance is not due to known confounding variables.
Introduction
Persons of black African descent in the Western world (African Americans in the U.S. and African Caribbeans in the United Kingdom) have a greater risk of heart failure than comparator populations of white European origin. It is not known whether this cardiac dysfunction occurs because of an ethnic difference in myocardial susceptibility, or because of an increased prevalence of factors that contribute to ventricular dysfunction among African Caribbeans, such as left ventricular hypertrophy (LVH), type 2 diabetes mellitus, obesity, and high blood pressure (BP). In addition, interpretation of comparator studies performed in patients with established end organ failure is made more difficult by possible differential effects of complex treatment regimes. What is required is a study performed at an earlier stage of disease, with stratification or adjustment for risk factors.
The earliest cardiac consequence of hypertension is diastolic dysfunction, which is part of a continuum of ventricular impairment ending in systolic heart failure. However, until relatively recently it has been difficult to reliably quantify diastolic dysfunction.
The advent of tissue Doppler technology has provided a solution to some of the problems associated with traditional Doppler echocardiography. Rather than interpreting patterns of blood flow, it measures myocardial velocities directly and is more reproducible than historically used echocardiographic methods for assessing diastolic function, such as the Valsalva maneuver or pulmonary vein flow. It provides measures that are less affected by volume status or vasodilator drug therapy than are conventional techniques, and when combined with the transmitral early filling wave (E) to form a ratio (E/E'), provides an estimate of left atrial filling pressures.
In this study, tissue Doppler was used to investigate whether diastolic function differs between hypertensive persons of African-Caribbean origin and white Europeans, and whether any differences observed could be explained by potential confounding variables.