Introduction: Coronary microvascular dysfunction (CMD) is a common condition contributing to heterogenous cardiac diseases, such as myocardial ischemia and heart failure. The pathogenesis of CMD is not fully understood, and current studies mainly measured microvascular function only in very selected population with a cross-sectional design. Therefore, data on the contribution of classical cardiovascular risk factors – and in particular of type 2 diabetes (T2DM) - on the genesis of CMD in the general population are scarce and partly contrasting. Therefore, we investigated the role of T2DM on CMD development in an all-comer population.

Methods: 271 patients undergoing elective coronary angiography at two timepoints at least 6 months apart were included; average time between the two coronary angiographies was 34±21 months. Microvascular function was measured retrospectively by means of angiography-based index of microvascular resistance (aIMR) at both timepoints in the same vessel (LAD in 93.4% of cases, LCx in 1.5%, RCA in 4.8%), in order to assess variation of microvascular function over time. An aIMR ≥25 was considered indicative of CMD.

Results: Of the 271 patients, 90 presented with T2DM at inclusion (33.3%). At baseline, CMD prevalence did not differ between patients with (n=33, 36.7%) and without T2DM (n=72, 40.0%, p=0.596); average baseline aIMR was comparable in the two groups (23.1±8.3 in T2DM vs. 23.2±7.7 in Non-T2DM patients, p=0.945). At the second timepoint, after an average of 34±21 months, the rate of development of de novo CMD was comparable between T2DM (n=18, 20.0%) and Non-T2DM patients (n=42, 23.3%, p=0.540). Also, the variation of aIMR normalized per year did not significantly differ between the two groups (-0.4±5.7 per year in T2DM vs. +0.7±6.5 per year in Non-T2DM patients, p=0.180).

Conclusion: In our study longitudinally assessing CMD in an all-comer population, we could not detect any significant difference in the natural history of CMD between patients with and without T2DM. However, it still remains elusive whether CMD progression is irrespective of T2DM or, on the contrary, the effects of T2DM on CMD progression may be ameliorated by modern antidiabetic treatments and higher intensity of care in T2DM patients. Further studies need to elucidate the role of T2DM in the development of CMD.