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Early impairment of coronary flow reserve in young men with borderline hypertension
H Laine1, O T Raitakari, H Niinikoski
1Department of Medicine, Turku Positron Emission Tomography Centre, Turku University, Finland. hannal@pet.tyks.fi
Insights
Young men with borderline hypertension exhibit reduced coronary reactivity, indicating impaired maximal vasodilator capacity. This occurs despite normal baseline myocardial blood flow and no signs of heart disease.
Area of Science:
- Cardiology
- Hypertension Research
- Vascular Physiology
Background:
- Previous research linked sustained hypertension to reduced coronary flow reserve.
- Hypertension can induce microvascular heart disease and left ventricular hypertrophy.
Purpose of the Study:
- To investigate coronary vasomotion abnormalities in young, asymptomatic men with borderline hypertension.
- To determine if early-stage hypertension affects coronary blood flow regulation.
Main Methods:
- Positron emission tomography (PET) with oxygen-15-labeled water measured myocardial blood flow.
- Dipyridamole infusion assessed coronary reactivity during hyperemia.
- Echocardiography evaluated left ventricular (LV) mass, dimensions, and function.
Main Results:
- Young men with borderline hypertension showed significantly lower coronary flow response to dipyridamole compared to controls.
- Maximal vasodilator capacity was impaired in the borderline hypertension group.
- No differences in LV mass, dimensions, or diastolic function were observed between groups.
Conclusions:
- Reduced coronary reactivity is present in young asymptomatic men with borderline hypertension.
- Impaired maximal vasodilator capacity, not altered baseline flow, underlies reduced coronary flow reserve.
- These findings highlight early vascular dysfunction in pre-hypertension.
Objectives:
The purpose of this study was to investigate whether functional abnormalities in coronary vasomotion are present in young healthy asymptomatic men fulfilling the World Health Organization (WHO) criteria for borderline hypertension.
Background:
Previous studies have reported reduced coronary flow reserve in middle-aged subjects with sustained hypertension and hypertension-induced microvascular heart disease or left ventricular hypertrophy.
Methods:
Myocardial blood flow was measured at baseline and during dipyridamole-induced hyperemia by means of positron emission tomography and oxygen-15-labeled water in asymptomatic young men with borderline hypertension (group 1: n = 16, mean +/- SD age 37 +/- 4 years, 24-h ambulatory blood pressure 135 +/- 10/81 +/- 9 mm Hg) and matched healthy control subjects (group 2: n = 19, age 35 +/- 3 years, 24-h ambulatory blood pressure 119 +/- 8/69 +/- 8 mm Hg, p < 0.001). Left ventricular (LV) mass, dimensions and function were measured by echocardiography.
Results:
LV mass, dimensions and diastolic function were similar in the study groups. Baseline myocardial blood flow was similar (0.83 +/- 0.21 vs. 0.80 +/- 0.22 ml/g per min, group 1 vs. group 2, respectively, p = NS), and a significant increase in flow was detected after dipyridamole infusion (0.56 mg/kg body weight in 4 min intravenously) in both groups. However, the flow response to dipyridamole was significantly lower in group 1, leading to lower hyperemic flow in group 1 than in group 2 (2.85 +/- 1.20 vs. 3.80 +/- 1.44 ml/g per min, respectively). Consequently, the coronary flow response was lower in hypertensive than in normotensive men (3.46 +/- 1.23 vs. 4.99 +/- 2.5 ml/g per min, group 1 vs. group 2, respectively, p < 0.05).
Conclusions:
These results demonstrate reduced coronary reactivity present in young asymptomatic men with borderline hypertension and no signs of hypertension-induced angina or left ventricular hypertrophy. Because baseline basal myocardial blood flow was unchanged, the reduction in coronary flow reserve depends on an impaired maximal vasodilator capacity.