CORRESPONDENCE: LETTER TO THE EDITOR
Relationship Between Coronary Microcirculatory Function and Aortic Stiffness in Diabetes
Attila Nemes, MD, PhD, FESC*
* Second Department of Medicine and Cardiology Center, Medical Faculty, University of Szeged, P. O. Box 427, H-6720 Szeged, Korányi fasor 6, Hungary (Email: nemes{at}in2nd.szote.u-szeged.hu).
I read with great interest the paper by Cortigiani et al. (1). This intriguing study confirmed that coronary flow reserve (CFR) provides independent prognostic information in diabetic and nondiabetic patients with known or suspected coronary artery disease (CAD) and negative dipyridamole stress echocardiography. I feel that a few additional comments are necessary.
It is well known that aortic distensibility and CFR as characteristics of coronary microcirculatory function are reduced in diabetes mellitus (DM) (2). Moreover, aortic stiffening may lead to early pulse wave reflection, causing an increase in central systolic blood pressure (BP), a decrease in diastolic BP, and an increase in pulse pressure. The elevation in systolic BP increases myocardial oxygen demand, reduces left ventricular ejection fraction, increases ventricular overload, and induces left ventricular hypertrophy. Because myocardial blood supply depends largely on pressure throughout diastole and the duration of diastole, the contemporary decrease in diastolic BP can compromise coronary perfusion, resulting in subendocardial ischemia (3). Reduction in CFR was found in patients with increased aortic stiffness compared with age-, gender-, and risk factor-matched controls with normal aortic distensibility (4). These findings direct our attention to consider aortic stiffness as an important parameter affecting coronary hemodynamics.
The prognostic role of CFR and DM in patients with known or suspected CAD has been confirmed, demonstrating that both variables are independently predictive of cardiovascular survival (5). In recent studies, it has been demonstrated that CFR and indices describing aortic distensibility can be measured simultaneously by echocardiography, helping us better understand their relationship to each other (4,6). To see whether aortic distensibility could add predictive value, patients with and without CAD were examined (7,8). It was found in patients with CAD that aortic distensibility did not offer any added information in predicting cardiovascular survival. The potential complementary prognostic information of aortic distensibility over CFR in patients without CAD and abnormal CFR found, which should be the topic of future research (8).
Interestingly, the number of studies evaluating the relationship between CFR and aortic stiffness in DM is limited (2,9,10). Alterations were found in CFR and aortic distensibility indices with correlations in diabetic patients with normal epicardial coronary arteries (2). In diabetic versus nondiabetic patients with CAD, aortic distensibility was reduced, but CFR was similar (9). Moreover, patients with aortic valve stenosis and type 2 DM had similar CFR and aortic distensibility indices compared with nondiabetic patients with aortic valve stenosis (10).
It should be considered that theoretically the echocardiographic evaluation of aortic distensibility simultaneously with CFR measurement is a relatively easy and patient-friendly method. Further investigations are warranted to examine the direct effect of aortic stiffness on coronary perfusion, especially in patients with DM. Furthermore, studies should evaluate the effect of antidiabetic drugs on coronary perfusion as well. Finally, studies evaluating the prognostic role of a combination of indices characterizing aortic distensibility and CFR in DM are warranted.
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References
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- Cortigiani L, Rigo F, Gherardi S, et al. Additional prognostic value of coronary flow reserve in diabetic and nondiabetic patients with negative dipyridamole stress echocardiography by wall motion criteria J Am Coll Cardiol 2007;50:1354-1361.[Abstract/Free Full Text]
- Nemes A, Forster T, Csanady M. Reduced aortic distensibility and coronary flow velocity reserve in diabetes mellitus patients with a negative coronary angiogram Can J Cardiol 2007;23:445-450.[ISI][Medline]
- Belz GG. Elastic properties and Windkessel function of the human aorta Cardiovasc Drugs Ther 1995;9:73-83.[CrossRef][ISI][Medline]
- Nemes A, Forster T, Csanady M. Reduction in coronary flow reserve in patients with increased aortic stiffness Can J Physiol Pharmacol 2007;85:818-822.[CrossRef][ISI][Medline]
- Nemes A, Forster T, Geleijnse ML, et al. The additional prognostic power of diabetes mellitus on coronary flow reserve in patients with suspected coronary artery disease Diabetes Res Clin Pract 2007;78:126-131.[CrossRef][ISI][Medline]
- Nemes A, Forster T, Csanady M. Relationship between coronary flow velocity reserve and aortic stiffness Am J Physiol Heart Circ Physiol 2006;290:H1311.[Abstract/Free Full Text]
- Nemes A, Geleijnse ML, Soliman OI, ten Cate FJ. Prognostic role of combination of coronary flow reserve with aortic distensibility indices Eur Heart J 2006;27:2607-2608.[Free Full Text]
- Nemes A, Forster T, Geleijnse ML, et al. Prognostic value of coronary flow reserve and aortic distensibility indices in patients with suspected coronary artery disease Heart Vessels 2008In press.
- Nemes A, Csanady M, Forster T. Aortic distensibility is reduced, but coronary flow velocity reserve is similar in diabetic versus non-diabetic patients with coronary artery disease Diabetes Res Clin Pract 2008In press.
- Nemes A, Forster T, Csanady M. Patients with aortic valve stenosis and type 2 diabetes have similar coronary flow reserve and aortic distensibility compared with non-diabetic patients with aortic valve stenosis Diabetes Res Clin Pract 2007;77:159-160.[CrossRef][ISI][Medline]
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