**3. Results**

#### *3.1. Comparison of CHD Patients and Healthy Volunteers*

The parameters assessed with the methods described above for all the CHD patients were different from the control values (Table 2). The first and second control group did not show statistically significant differences between themselves.


**Table 2.** The comparison of CHD patients and the control groups. The averaged values and the standard errors are presented. The *p*-value was calculated by a two-tailed *t*-test with unequal variance.

CHD—coronary heart disease; AI—aggregation index; CBV—capillary blood velocity; \* *p* < 0.05 for control group A.

The values for control groups A and B did not show statistically significant differences for AI and T1/2 (see Table 2), which proves the consistency of the laser aggregometry method. Unfortunately, other parameters (Tagg and CBV) could not be measured for both control groups, but they were consistent with our previous work [11]. Control group A was studied more recently and had a greater number of subjects than group B, so we used it in the analysis.

In CHD patients compared to the control group A, AI was higher by 20 ± 7% (*p* < 0.05), meaning more numerous aggregation, T1/2 was lower by 14 ± 9% (*p* < 0.05), meaning faster

aggregation, and Tagg was lower by 27 ± 7% (*p* < 0.05), showing faster doublet formation. As for CBV, it was smaller than the control, but significant only at *p* = 0.1 level due to high variation from person to person.

The CHD patients were divided into two groups by the presence of T2DM and they showed significant (*p* < 0.05) differences in some parameters (Table 3).

**Table 3.** The comparison of CHD patients with and without T2DM. The averaged values and the standard errors of the sample mean are presented. The *p*-value was calculated by a two-tailed *t*-test with unequal variance.


CHD—coronary heart disease; T2DM—type 2 diabetes mellitus; AI—aggregation index; CBV—capillary blood velocity; \* *p* < 0.05.

#### *3.2. Digital Capillaroscopy Results Matched with In Vitro Parameters*

Figure 3a–c shows the RBC aggregation parameters plotted as functions of CBV and the Pearson's r coefficient for each trend. AI for all the presented groups decreased with the increase of CBV, as indicated by the negative r. T1/2, on the other hand, increased and had positive r values. Tagg remained constant for the whole CBV range. These results show that for patients with high CBV the aggregation process in vitro was weaker compared to the patients with low CBV: The aggregation was less numerous and the doublet formation took longer.

**Figure 3.** The individual values of AI (**a**), T1/2 (**b**), and Tagg (**c**) for groups of patients with and without T2DM versus the CBV. The linear fit and the Pearson's r coefficient are shown. CHD—coronary heart disease; T2DM—type 2 diabetes mellitus; CBV—capillary blood velocity.

No statistically significant difference in aggregation was found between several patient subgroups, including the division by gender and smoking habits. AI weakly correlated with BMI (Pearson's r = 0.29) and did not correlate with age (r = −0.05).
