Age and Microvascular Function in Patients without Obstructive Coronary Artery Disease -

At present, there is increasing interest in the microvascular function of patients with and without obstructive coronary artery disease of different ages. However, these “physiological” effects of age on microvascular function have never been directly quantified on patients without obstructive CAD. Prior studies have focused on patients with angina and obstructive CAD, and the effects on aging.

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The aim of this prospective study was to quantitatively investigate the effect of age on microvascular function in patients with normal coronary arteries.

In 314 patients with angina and no obstructive CAD (ANOCA), microvascular function was assessed using the continuous thermodilution method. In 305 patients, the link between age and both resting and hyperemic myocardial blood flow was assessed, looking at coronary flow reserve (CFR) and microvascular resistance reserve (MRR). Also, patients were divided into three groups according to age quartile (≤52 [24,9%], 53-64 [49,2%], and ≥65 years [25,9%]).

Mean patient age was 59, and they were mostly women. Mean resting coronary flow showed no significant difference between groups. There was a trend towards reduced mean hyperemic flow (Qmax) as age increased (p=0,083). Resistance increased significantly with age (p=0,005). In consequence, MRR decreased with age (3,2±1,2, 3,1±1,0, 2,9±0,9; p=0,038). This trend was present in patients with (n=121) and without (n=184) coronary microvascular dysfunction (CMD).

Conclusion

There is increased hyperemic microvascular resistance and reduced microvascular function depending on age. This reduction was present in patients with and without microvascular dysfunction, and was particularly apparent in patients without obstructive CAD, which emphasizes the fact that this phenomenon is independent of atherosclerosis.