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Coronary microvascular disease in hypertensives
A R Lucarini1, E Picano, A Salvetti
1Clinica Medica I, University of Pisa, Italy.
Insights
Essential hypertension may involve coronary microvascular disease, impacting coronary flow reserve. This condition, identified by dipyridamole-echocardiography, is linked to arrhythmia risk and improves with antihypertensive treatment.
Area of Science:
- Cardiology
- Hypertension Research
- Vascular Biology
Background:
- Arterial hypertension affects coronary circulation via coronary artery disease, left ventricular hypertrophy, and microvascular disease.
- Coronary microvascular disease (CMD) in hypertensives may reduce coronary flow reserve and shift the autoregulation curve.
- Dipyridamole-echocardiography can detect microvascular dysfunction in conditions like Syndrome X and hypertrophic cardiomyopathy.
Purpose of the Study:
- To investigate the presence and consequences of coronary microvascular disease in patients with essential hypertension.
- To assess the utility of dipyridamole-echocardiography in identifying hypertensive patients with CMD.
- To explore the relationship between CMD, ventricular arrhythmias, and response to antihypertensive treatment.
Main Methods:
- Utilized dipyridamole-echocardiography to assess coronary circulation.
- Evaluated mild-moderate essential hypertensives with normal epicardial arteries and increased forearm vascular resistance.
- Monitored for echocardiographically silent ST segment depression, a marker of ischemic-like response.
Main Results:
- Dipyridamole infusion induced ST segment depression in hypertensives, indicating CMD despite normal epicardial arteries.
- This response was associated with reduced coronary reserve and increased risk of ventricular arrhythmias.
- The observed microvascular dysfunction and forearm vascular resistance were reversible with chronic antihypertensive treatment.
Conclusions:
- Coronary microvascular disease is a significant complication in essential hypertension, affecting coronary flow reserve.
- Dipyridamole-echocardiography can identify this microvascular dysfunction in hypertensives.
- Chronic antihypertensive therapy can reverse CMD and reduce associated risks, including ventricular arrhythmias.
Abstract:
Arterial hypertension can badly affect coronary circulation through several mechanisms that are not mutually exclusive, namely, coronary artery disease, left ventricular hypertrophy, and microvascular disease. Theoretical and experimental data suggest that coronary microvascular disease may exist in hypertensives, in whom it can cause both a reduction of coronary flow reserve and a shift to the right of the coronary flow autoregulation curve. To address this issue, we used dipyridamole- echocardiography test, which causes ischemic-like ST segment depression with no detectable changes in left ventricular function in different subsets of patients with microvascular disease (Syndrome X; Hypertrophic cardiomyopathy; acute heart rejection). We found that dipyridamole infusion can cause a similar pattern of response (i.e., echocardiographically silent ST segment depression) in mild-moderate essential hypertensives with normal epicardial coronary arteries, without left ventricular hypertrophy, with increased forearm minimal vascular resistances and with a reduced coronary reserve. This pattern of response identifies hypertensives with higher risk of ventricular arrhythmias, is amplified by acute reduction of diastolic blood pressure and can be reversed, together with the reduction of forearm vascular resistances by chronic antihypertensive treatment. Taken together these findings suggest that microvascular coronary disease can exist in hypertensives with two adverse consequences, consistent with the experimental background: the reduction of coronary flow reserve as well as a shift to the right of the coronary flow autoregulation curve.