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Trends in left ventricular function over three years in the Tecumseh Study
J Amerena1, S Nesbitt, L Krause
1Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, USA.
Insights
Sustained hypertension significantly impairs left ventricular diastolic function, indicated by a reduced early/late diastolic filling rate (E/A ratio). This decline, alongside increased heart rate and altered stroke volume, suggests potential cardiovascular changes over time.
Area of Science:
- Cardiology
- Physiology
Background:
- Left ventricular diastolic function is crucial for heart health.
- Hypertension is a major cardiovascular risk factor.
- Understanding the long-term effects of blood pressure on cardiac function is vital.
Purpose of the Study:
- To investigate the relationship between sustained hypertension and left ventricular diastolic function.
- To assess changes in diastolic filling rates, heart rate, and stroke volume over time in relation to blood pressure status.
Main Methods:
- Analysis of data from the Tecumseh Blood Pressure study.
- Categorization of participants into normotensive (NN), one-time hypertensive (OH), and sustained hypertensive (SH) groups based on blood pressure measurements over 3 years.
- Evaluation of early/late diastolic filling rate (E/A ratio), heart rate, and stroke volume index.
Main Results:
- Sustained hypertensive subjects exhibited a significantly decreased E/A ratio compared to normotensive and one-time hypertensive groups.
- All groups showed a decline in E/A ratio over 3 years, consistent with age-related changes.
- Heart rates were initially higher in hypertensive groups and increased over time, with the largest increase in the sustained hypertensive group.
- Stroke volume index changes showed an inverse pattern to heart rate changes, with the smallest increase in the sustained hypertensive group.
Conclusions:
- Sustained hypertension is associated with reduced left ventricular diastolic function.
- Age-related decline in diastolic filling occurs in all blood pressure groups.
- Weight gain may influence sympathetic tone, potentially exacerbating cardiovascular changes in hypertensive individuals.
- Mild blood pressure elevation may reduce diastolic function and alter cardiac responsiveness to sympathetic stimulation.
Abstract:
The relationship between blood pressure and left ventricular diastolic function was examined in participants of the Tecumseh Blood Pressure study. When subjects were divided into three blood pressure groups according to blood pressure levels 3 years apart, it was found that subjects who were had sustained "hypertension" at both time points (SH) had a decreased early/late diastolic filling rate (E/A ratio) compared to subjects who were hypertensive at only one of the timepoints (OH) and those who were consistently normotensive (NN) (1.71 +/- 0.02 NN vs 1.55 +/- 0.05 OH, (p < 0.0001) vs 1.56 +/- 0.07 SH, (p < 0.04)). This relative order was maintained when the second estimation of diastolic filling was performed 3 years later, but the E/A ratio had decreased significantly in all groups (1.54 +/- 0.01 NN vs 1.45 +/- 0.03 OH (p < 0.01) vs 1.37 +/- 0.06 SH (p < 0.006)), consistent with an age-related reduction in diastolic filling. Heart rates were significantly higher in the hypertensive groups initially (63.5 NN vs 66.2 OH (p < 0.03) vs SH 67.3 (p < 0.01)) and increased in all groups over time, with the largest increase in the SH group (64.9 +/- 0.04 NN vs 67.8 +/- 1.02 OH (p < 0.0001) vs 70.9 +/- 1.6 SH (p < 0.01)). Stroke volume index changed in all groups over time, with the increase greatest in the NN group and least in the SH groups the reverse of this pattern was seen for changes in heart rate. All subjects gained weight over the 3 years of the study so that these unexpected changes in stroke volume index and heart rate could be a consequence of a weight gain-related increase in the sympathetic tone, although we have no direct evidence that this is the case. Should this be so, the smaller increase in stroke volume in conjunction with the larger increase in the heart rate in the sustained hypertensive group may reflect the effects of mild blood pressure elevation in producing a reduction in left ventricular diastolic function associated with a decrease in the inotropic responsiveness of the heart to enhanced sympathetic tone.