Relationship Between Spotty Calcification And Plaque Stability In Patients With Coronary Heart Disease:an Optical Coherence Tomography Study

Objective:The relationship between the characteristics of calcification deposition and plaque stability in patients with coronary heart disease(CAD)has not been incompletely understood.Optical coherence tomography(OCT)was used to detect the morphological features of spotty calcification in patients with acute myocardial infarction(AMI),unstable angina pectoris(UAP)and stable angina pectoris(SAP),and to further explore the relationship between these features and plaque rupture.Methods:A total of 101 patients with CAD who received coronary angiography(CAG)and OCT examination in our hospital from January 2019 to January 2021 were retrospectively analyzed.They were divided into three groups according to disease types:AMI group(n=49),UAP group(n=22)and SAP group(n=30).The general information and laboratory examination data of the selected patients were collected,and the plaque types and data of the criminal lesions(20-mm segment)were analyzed and measured by the software of OCT system.According to the presence or absence of plaque rupture under OCT examination,43 patients were divided into the ruptured plaque group and 58 patients were divided into the unruptured plaque group.All statistical analysis were performed using SPSS 26.0(SPSS,Chicago,IL,USA).A p value less than 0.05 was regarded as statistically significant.Results:1.Spotty calcification was found in 29 of 43 patients in the ruptured plaque group,accounting for 67.4%.Quantitative characteristics of spotty calcification:A total of 66 spotty calcifications were detected in the ruptured plaque group.The average depth of spotty calcification was 60.16±29.00μm,the arc was 39.76±18.33°and the length was 1.52±0.79mm.One case(2.3%)of large calcification was found in the ruptured plaque group.The arc of the large calcification was 95°,the length was 4.5mm,and the depth was only 50μm.It was a superficial calcification lesion,which tended to be unstable.Spotty calcification was found in 21(36.8%)of 58 patients in the unruptured plaque group.Quantitative characteristics:A total of 39 spotty calcifications were detected in the unruptured plaque group.The average depth of spotty calcifications was 125.28±47.97μm,the arc was 62.69±26.62°,and the length was 2.23±1.67mm.Compared with the ruptured plaque group,the spotty calcifications in the unruptured plaque group were deeper,more arc and longer.There were statistically significant differences(P<0.01),and the lesions were more likely to be stable.21 cases(36.2%)of large calcifications were detected in the unruptured plaque group.The average arc was 99.95±9.01°,the length was 2.94±1.88mm,and the depth was 131.53±32.29μm.Most of the lesions were deep calcifications,which tended to be stable.2.The presence of spotty calcification was positively correlated with plaque rupture(correlation coefficient r=0.31),and there was a statistically significant difference(P<0.01).On the contrary,the presence of large calcification was negatively correlated with plaque rupture(r=-0.41),and there was a statistically significant difference(P<0.01).The arc(r=-0.62)and depth(r=-0.77)of spotty calcification were negatively correlated with the occurrence of plaque rupture,and there was a statistically significant difference(P<0.01).The length of spotty calcification(r=-0.26)was negatively correlated with the occurrence of plaque rupture,and the difference was statistically significant(P<0.05).3.Univariate logistic regression analysis showed that the related risk factors for plaque rupture occurred and spotty calcification(OR:5.18,95%CI:2.60 10.33,P<0.001),the arc of spotty calcification(OR:0.983,95%CI:0.93 0.96,P<0.001),the depth of spotty calcification(OR:0.93,95%CI:0.91 0.95,P<0.001),the existence of thin-cap fibroatheroma(TCFA)(OR:16.44,95%CI:5.51-49.01,P<0.001),macrophage infiltration(OR:2.41,95%CI:1.18-4.89,P=0.015),microchannels(OR:3.23,95%CI:1.70-6.15,P<0.001).Except for macrophage infiltration(P=0.015),the remaining five variables(P<0.01 in univariate test)were analyzed in multivariate modeling.When all five parameters were presented,the probability of plaque rupture increased to 94.2%.Multivariate logistic regression analysis results indicated that the existence of TCFA(OR:9.83,95%CI:1.15 84.16,P=0.037)associated with the occurrence of plaque rupture independently,and the arc of spotty calcification(OR:0.96,95%CI:0.94 0.99,P=0.011)and depth(OR:0.94,95%Cl:0.91 0.97,P<0.001)were independent of classical risk factors of vulnerable plaques,were still associated with the occurrence of plaque rupture independently.4.Compared with the unruptured plaque group,the presence of TCFA(48.8%vs.5.2%),spotty calcification(67.4%vs.36.2%)and thrombosis(32.6%vs.8.6%)were higher in the ruptured plaque group,with statistically significant differences(P<0.01).The minimum lumen diameter(1.27±0.37 vs.1.50±0.37mm)and the minimum lumen area(1.67±0.64 vs.2.07±0.76mm2)in the ruptured plaque group were lower than those in the unruptured plaque group,with statistically significant differences(P<0.01).The percentage of area stenosis in the ruptured plaque group(71.61±10.60 vs.66.08± 13.02%)was higher than that in the non-ruptured group,with statistical difference(P<0.05).There were 33 cases with lipid-rich plaque(76.7%)in the ruptured plaque group,and 32 cases(55.2%)in the non-rupture group,with statistical difference(P<0.05).Macrophage infiltration was found in 17 cases(39.5%)of the ruptured group and 12 cases(20.7%)of the non-rupture group,with statistical difference(P<0.05).There were 24 microchannels(53.3%)in the ruptured group,and 17 microchannels(29.3%)in the non-rupture group,and the difference was statistically significant(P<0.05).Homocysteine in the ruptured group(16.20±6.51 umol/L)was higher than that in the unruptured group(13.39±3.92 umol/L),and the difference was statistically significant(P<0.01).White blood cell count(10.09±3.72 vs.7.62±2.70×109/L)and neutrophil count(7.53±3.68 vs.5.18±2.56×109/L)in the ruptured group were significantly higher than those in the non-rupture group,with statistical significance(P<0.01).The hemoglobin of the ruptured group was lower(138.81±24.89 vs.149,19±16.47 g/L),and the difference was statistically significant(P<0.05).Conclusions:1.There is a clear relationship between the quantitative characteristics of spotty calcification seen by OCT and plaque stability.The smaller of the arc and the shallower of the depth in spotty calcification,the plaque tends to be unstable and the more prone to rupture.2.Spotty calcification may serve as a new vulnerable plaque phenotype.