Abstract
Aims: Clonal hematopoiesis of indeterminate potential (CHIP), which has recently been shown to be an age-related phenomenon, is associated with cardiovascular diseases, including atherosclerosis and stroke. This study focused on the association between CHIP and short- and long-term stroke recurrence in patients with acute ischemic stroke and intracranial atherosclerotic stenosis (ICAS).
Methods: This study included 4,699 patients with acute ischemic stroke based on data from the Third China National Stroke Registry (CNSR-III), a nationwide prospective hospital-based registry. The ICAS assessment followed the criteria established by the Warfarin-Aspirin Symptomatic Intracranial Disease Study and Brain Imaging. Atherosclerosis Scores (AS) were used to assess the atherosclerosis burden, as determined by the number and severity of steno-occlusions in the intracranial arteries. The primary outcome was stroke recurrence three months and one year after the event.
Results: Among the 4,699 patients, 3,181 (67.7%) were female, and the median age was 63.0 (55.0–71.0) years. We found that CHIP significantly increased the risk of stroke recurrence at the 1-year follow-up in patients with ICAS (adjusted hazard ratio [HR] 2.71, 95% confidence interval [CI] (1.77–4.16),P for interaction, 0.008).
Conclusions: Our results revealed that CHIP might have a significant impact on the long-term risk of recurrent stroke, particularly in patients with a higher atherosclerotic burden.
Keywords: Ischemic Stroke, Clonal Hematopoiesis, Aging, Stroke, Intracranial Arteriosclerosis, Atherosclerotic burden
Introduction
Clonal hematopoiesis of indeterminate potential (CHIP) is commonly defined as the presence of an expanded somatic blood cell clone resulting from somatic mutations in individuals without other hematological abnormalities. These mutations mostly occur in three genes: DNMT3A, TET2 and ASXL1 1 , 2) . Research has shown that CHIP is associated with higher all-cause mortality and an increased risk of stroke, coronary artery disease, and coronary atherosclerosis burden 3 - 5) . Experimental results in mice indicate that CHIP accelerates the development of atherosclerosis by promoting inflammasome activation and regulating inflammatory factors such as interleukin (IL)-1β. This regulation may play a crucial role in the atherosclerotic development associated with CHIP. Recent studies have also demonstrated that CHIP is associated with recurrent stroke in patients with first-ever ischemic stroke and that inflammation may be a critical mechanism 6 , 7) . The focus on the possible inflammatory correlation between CHIP and atherosclerosis serves as a reminder to researchers of the need to further investigate stroke recurrence in patients stratified by the intracranial atherosclerotic burden.
Stroke is the second leading cause of death worldwide and it is a complex multifactorial disease, in which genetic and environmental determinants play important roles 8 - 10) . In some populations, particularly in Asia, intracranial atherosclerotic stenosis (ICAS) is one of the most prevalent causes of stroke and is thought to be associated with the risk of stroke recurrence at one year 11 , 12) . However, the correlation among CHIP, ICAS, and stroke recurrence remains unclear.
This study aimed to investigate the association between CHIP and the short- and long-term risks of stroke recurrence in patients with ischemic stroke, while considering various ICAS scenarios.
Methods
Study Population
Data were collected from the Third China National Stroke Registry (CNSR-III), a nationwide, prospective hospital-based registry. The registry included 15,166 patients with ischemic stroke or transient ischemic attack (TIA) in China. Individuals over 18 years of age with TIA or ischemic stroke within 7 days of symptom onset were recruited from 201 participating hospitals in 26 provinces and municipalities between August 2015 and March 2018 13) . Patients diagnosed with transient ischemic attack (TIA) or a history of prior stroke or hematological malignancy were excluded ( Fig.1 ) . CNSR-III was approved by the Ethics Committee of Beijing Tiantan Hospital and all participating centers. Written informed consent was obtained from all the participants. The study complied with the principles of the Declaration of Helsinki.
Fig.1.
Flowchart of the included and excluded patients
Blood samples were collected, and biomarkers were tested at baseline. All patients underwent standard imaging examinations during hospitalization, including brain magnetic resonance imaging (MRI) and at least one intracranial vascular assessment, such as magnetic resonance angiography (MRA), computed tomography angiography (CTA), or digital subtraction angiography (DSA). Patients with missing vascular imaging findings were excluded from this study. Trained research coordinators uploaded detailed data, including clinical phenotypes, etiological classifications, neuroimaging, biomarkers, and clinical outcomes, using an electronic data capture system (EDC).
Evaluations of ICAS and Atherosclerosis Burden
Intracranial artery stenosis or occlusion was assessed based on at least one of the aforementioned vascular imaging results. The degree of ICAS was identified by neuroimaging experts according to the Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) study criteria 14 , 15) . Assessments of the intracranial arteries included the anterior, middle, posterior, intracranial carotid, basilar, and intracranial vertebral arteries. The patients were divided into two groups according to the degree of ICAS: “ICAS=0” indicating no stenosis, “ICAS ＞0” indicating 0–99% stenosis or occlusion. Atherosclerosis Scores (AS) were used to evaluate the atherosclerosis burden, which was determined by the number and degree of steno-occlusion of the intracranial arteries 16) . AS was calculated as the sum of the scores for each artery based on the following criteria: 0, ＜50% stenosis; 1, 50–99% stenosis; and 2, occlusion.
Outcomes
The primary outcome of this study was recurrent stroke three months and one year after symptom onset. Recurrent stroke was defined as a new-onset focal neurological deficit induced by cerebral ischemic or hemorrhagic events. Confirmation was made using computed tomography or MRI, following the World Health Organization criteria 17) . The patients were interviewed face-to-face at three months and one year by trained research personnel 13) . Confirmation of stroke events was sought from the treating hospitals. Suspected stroke events without hospitalization were confirmed by an independent end-point judgment committee.
Identification of CHIP
The identification of CHIP was based on whole genome sequencing (WGS) data, which was performed on 10,914 patients as part of the genetic substudy within CNSR-III 18) . DNA was extracted from the white blood cells (WBCs) of each sample and WGS was performed using the BGISEQ-500 platform. The intended average sequencing depth for each participant was set greater than 30 times 18) . CHIP carriers were identified based on a prespecified list of variants in 74 genes known to be repeatedly mutated in bone marrow cancer. Additional details have been published previously 3 , 7) .
Statistical Analysis
Continuous variables are presented as the mean (standard deviation [SD]) and median (interquartile range [IQR]), unless otherwise noted. Wilcoxon’s t-test was used to compare continuous variables between the groups.
Categorical variables were reported as frequencies with percentages and analyzed using the χ2 test. The patients were divided into groups according to ICAS or AS to compare the rates of stroke recurrence at three months and one year between the CHIP and non-CHIP carriers. A Cox proportional hazards regression model was used to test the association between CHIP carriers and the outcomes. We used stabilized inverse probability of treatment weighting (IPTW) based on the propensity score (PS) to balance the characteristics of CHIP and non-CHIP carriers. Model 1 included age, sex, body mass index (BMI), smoking, drinking, stroke, TIA, hypertension, diabetes, lipids, coronary heart disease (CHD), myocardial infarction (MI), National Institute of Health Stroke Scale (NIHSS) scores, and interleukin-6 (IL-6) levels, which were used to calculate PS when using the stabilized IPTW.
Results
Patient Characteristics and Detection of CHIP
In total, 4,699 patients with ischemic stroke with available data were recruited for this study. Of the 4,699 patients (3.8%) were identified as CHIP carriers. The median age of the participants was 63.0 (55.0–71.0) years at the time of DNA sample collection, and 67.7% (3,181/4,699) were female. The baseline characteristics of the CHIP and non-CHIP carriers are shown in Table 1 .
Table 1. Baseline characteristics of the enrolled patients.
| Variables |
Total (N= 4699 [100%]) |
CHIP carriers (N= 180 [3.8%]) |
Non-CHIP carriers (N= 4519 [96.2%]) |
P Value |
|---|---|---|---|---|
| Age, median (IQR), y | 63.0 (55.0–71.0) | 69.0 (62.0–77.5) | 63.0 (55.0–70.0) | ＜0.0001 |
| Age, n. (%) | ＜0.0001 | |||
| ＜ 40 | 108 (2.3) | 1 (0.6) | 107 (2.4) | |
| 40-49 | 485 (10.3) | 13 (7.2) | 472 (10.4) | |
| 50-59 | 1185 (25.2) | 22 (12.2) | 1163 (25.7) | |
| 60-69 | 1606 (34.2) | 57 (31.7) | 1549 (34.3) | |
| 70-79 | 1022 (21.7) | 54 (30.0) | 968 (21.4) | |
| ≥ 80 | 293 (6.2) | 33 (18.3) | 260 (5.8) | |
| Sex, n. (%) | 0.01 | |||
| Female | 3181 (67.7) | 106 (58.9) | 3075 (68.0) | |
| BMI, kg/m2, median (IQR), y | 24.5 (22.6–26.7) | 23.9 (22.0–26.2) | 24.5 (22.6–26.7) | 0.05 |
| Current smoking, n. (%) | 1552 (33.0) | 49 (27.2) | 1503 (33.3) | 0.25 |
| Current drinking, n. (%) | 832 (17.7) | 25 (13.9) | 807 (17.9) | 0.02 |
| Medical history, n. (%) | ||||
| Hypertension, | 2876 (61.2) | 107 (59.4) | 2769 (61.3) | 0.62 |
| Diabetes mellitus | 1120 (23.8) | 47 (26.1) | 1073 (23.7) | 0.46 |
| Dyslipidemia | 334 (7.1) | 12 (6.7) | 322 (7.1) | 0.81 |
| CHD | 446 (9.5) | 16 (8.9) | 430 (9.5) | 0.78 |
| MI | 75 (1.6) | 1 (0.6) | 74 (1.6) | 0.26 |
| Angina | 152 (3.2) | 10 (5.6) | 142 (3.1) | 0.07 |
| AF | 336 (7.2) | 16 (8.9) | 320 (7.1) | 0.36 |
| HF | 32 (0.7) | 1 (0.6) | 31 (0.7) | 0.83 |
| Prior TIA | 114 (2.4) | 3 (1.7) | 111 (2.5) | 0.50 |
CHIP, clonal hematopoiesis of indeterminate potential; BMI, body mass index; CHD, coronary heart disease; MI, Myocardial infarction; AF, Atrial fibrillation; HF, Heart failure.
The median age of CHIP carriers was significantly older than that of non-CHIP carriers (69.0 [62.0–77.5] vs. 63.0 [55.0–70.0], P＜0.0001). In addition, the prevalence of CHIP carriers increases with age. Among the patients, 1.9% were aged 50–59 years (22/1,185), 3.5% were aged 60–69 years (57/1,606), 5.3% were aged 70–79 years (54/1,022), and 11.3% were aged ≥ 80 years (33/293). There was a lower rate of females among CHIP carriers (58.9% vs. 68.0%, P=0.01).
Association between CHIP and the Baseline Clinical Characteristics
Table 1 shows that CHIP carriers were significantly older and had a lower BMI than non-CHIP carriers (23.9 [22.0–26.2] kg/m2 versus 24.5 [22.6–26.7] kg/m2, P=0.05] and did not frequently have a history of current alcohol abuse (13.9% vs. 17.9%, P=0.02). Other vascular risk factors, such as hypertension, diabetes, dyslipidemia, CHD, MI, atrial fibrillation, and prior TIA, were generally comparable between CHIP and non-CHIP carriers. The proportion of CHIP carriers did not exhibit any significant difference compared with non-CHIP carriers when stroke was classified into five subtypes according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria 19) ( Table 2 ) . No significant differences were observed between CHIP and non-CHIP carriers in terms of NIHSS scores upon arrival at the hospital (＞3; 50.0% versus 50.5%, P=0.90), presence of ICAS (＞0; 56.1% versus 56.2%, P=0.99), and AS score (1.6±1.8 versus 1.6±1.9, P=0.96).
Table 2. Stroke characteristics and atherosclerosis scores of the enrolled patients.
| Variables |
Total (N = 4,699 [100%]) |
CHIP carriers (N = 180 [3.8%]) |
Non-CHIP carriers (N = 4,519 [96.2%]) |
P Value |
|---|---|---|---|---|
| TOAST classification, n. (%) | 0.33 | |||
| LAA | 1652 (35.2) | 58 (32.2) | 1594 (35.3) | |
| CE | 256 (5.4) | 12 (6.7) | 244 (5.4) | |
| SAO | 954 (20.3) | 29 (16.1) | 925 (20.5) | |
| SOE | 66 (1.4) | 2 (1.1) | 64 (1.4) | |
| SUE | 1771 (37.7) | 79 (43.9) | 1692 (37.4) | |
| Admitting NIHSS, n | 0.51 | |||
| Mean±SD | 4.5±4.3 | 4.7±4.3 | 4.5±4.3 | |
| Admitting NIHSS, n. (%) | 0.90 | |||
| ≤ 3 | 2327 (49.5) | 90 (50.0) | 2237 (49.5) | |
| ＞3 | 2372 (50.5) | 90 (50.0) | 2282 (50.5) | |
| ICAS | 0.99 | |||
| 0 | 2060 (43.8) | 79 (43.9) | 1981 (43.8) | |
| ＞0 | 2639 (56.2) | 101 (56.1) | 2538 (56.2) | |
| AS | 0.96 | |||
| Mean±SD | 1.6±1.9 | 1.6±1.8 | 1.6±1.9 |
TOAST, Trial Org 10,172 in Acute Stroke Treatment; LAA, Large-artery atherosclerosis; CE, Cardiac embolism; SAO, Small-artery occlusion; SOE, stroke of other determined etiology; SUE, stroke of undetermined etiology; NIHSS, National Institutes of Health Stroke Scale. “ICAS = 0” indicating no stenosis, “ICAS ＞0” indicating 0-99% stenosis or occlusion. Atherosclerosis Scores (AS) were used to evaluate the atherosclerosis burden, which was determined by the number and degree of steno-occlusion of the intracranial arteries.
Table 3 compares the laboratory tests and examination results of CHIP carriers with those of non-CHIP carriers. CHIP carriers had a higher rate of elevated hypersensitive CRP (3.1 [1.2–6.5] mg/L vs. 1.9 [0.9–4.8] mg/L, P=0.01) and a higher level of IL-6 (3.7 [2.1–6.6] pg/mL vs. 2.7 [1.7–5.2] pg/mL, P=0.0001). Compared to non-CHIP carriers, CHIP carriers had a lower lymphocyte level (1.5 [1.1–2.1] 109/L versus 1.7 [1.3–2.2] 109/L, P=0.003) and a lower hemoglobin level (137.0 [128.0–150.0] g/L versus 142.0 [131.0–152.0] g/L, P=0.005]. WBC and neutrophil counts were higher in CHIP carriers than in non-CHIP carriers, although the differences were not statistically significant (7.3 [5.8–8.9] 109/L vs. 7.1 [5.8–8.6] 109/L, P=0.48; 4.9 [3.7–6.2] 109/L vs. 4.6 [3.5–5.9] 109/L, P=0.08). Additionally, there were no differences between the two groups regarding blood lipid indicators, such as free fatty acids, triglycerides, total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol.
Table 3. Clinical characteristics of CHIP and non-CHIP carriers.
| Variables |
Total (N = 4699 [100%]) |
CHIP carriers (N = 180 [3.8%]) |
Non-CHIP carriers (N = 4519 [96.2%]) |
P Value |
|---|---|---|---|---|
| SBP at admission, mmHg | 150.0 (136.5–165.0) | 151.0 (137.3–168.5) | 150.0 (136.5–165.0) | 0.35 |
| DBP at admission, mmHg | 86.5 (79.0–96.0) | 88.0 (80.0–95.8) | 86.5 (79.0–96.0) | 0.98 |
| Hypersensitive CRP, mg/L | 1.9 (0.9–4.8) | 3.1 (1.2–6.5) | 1.9 (0.9–4.8) | 0.01 |
| CRP, mg/L | 2.6 (1.1–6.0) | 3.3 (1.9–13.2) | 2.6 (1.1–5.9) | 0.07 |
| WBC, 109/L | 7.1 (5.8–8.6) | 7.3 (5.8–8.9) | 7.1 (5.8–8.6) | 0.48 |
| LY, 109/L | 1.7 (1.3–2.2) | 1.5 (1.1–2.1) | 1.7 (1.3–2.2) | 0.003 |
| MONO, 109/L | 0.4 (0.3–0.6) | 0.4 (0.3–0.5) | 0.4 (0.3–0.6) | 0.57 |
| NA, 109/L | 4.6 (3.5–5.9) | 4.9 (3.7–6.2) | 4.6 (3.5–5.9) | 0.08 |
| EA, 109/L | 0.1 (0.1–0.2) | 0.1 (0.1–0.1) | 0.1 (0.1–0.2) | 0.23 |
| BA, 109/L | 0.0 (0.0–0.0) | 0.0 (0.0–0.0) | 0.0 (0.0–0.0) | 0.57 |
| Hgb, g/L | 142.0 (131.0–152.0) | 137.0 (128.0–150.0) | 142.0 (131.0–152.0) | 0.005 |
| PLT count, 109/L | 212.0 (177.0–252.0) | 220.0 (172.0–264.0) | 211.0 (177.0–251.5) | 0.44 |
| A/G | 1.6 (1.4–1.8) | 1.6 (1.4–1.8) | 1.6 (1.4–1.8) | 0.81 |
| FFA, mmol/L | 0.7 (0.5–1.0) | 0.7 (0.5–1.0) | 0.7 (0.5–1.0) | 0.76 |
| Triglyceride, mmol/L | 1.4 (1.0–1.9) | 1.4 (1.1–1.8) | 1.4 (1.0–1.9) | 0.86 |
| TC, mmol/L | 4.0 (3.4–4.8) | 4.2 (3.5–4.9) | 4.0 (3.4–4.8) | 0.30 |
| HDL-C, mmol/L | 0.9 (0.8–1.1) | 1.0 (0.8–1.1) | 0.9 (0.8–1.1) | 0.30 |
| LDL-C, mmol/L | 2.4 (1.8–3.0) | 2.5 (1.9–3.3) | 2.4 (1.8–3.0) | 0.07 |
| IL-6, pg/mL | 2.8 (1.7–5.2) | 3.7 (2.1–6.6) | 2.7 (1.7–5.2) | 0.0001 |
| IL-6R, | 39770.2 (31033.6–49706.5) | 39608.7 (32063.5–50337.1) | 39770.4 (31011.5–49668.1) | 0.37 |
| IL-1RA, pg/mL | 351.2 (262.1–509.1) | 379.3 (276.8–547.2) | 349.7 (261.6–505.3) | 0.01 |
| HCY, smol/L; | 15.2 (12.2–20.4) | 15.2 (12.6–20.4) | 15.1 (12.1–20.5) | 0.42 |
| D-D, sg/ml | 1.2 (0.6–2.1) | 1.2 (0.5–2.2) | 1.2 (0.6–2.1) | 0.65 |
| ALB, g/L | 40.2 (37.8–43.0) | 39.7 (37.4–43.0) | 40.3 (37.8–42.9) | 0.41 |
| Cr, smol/L | 69.0 (58.0–81.0) | 69.5 (56.0–86.0) | 69.0 (58.0–81.0) | 0.76 |
SBP, systolic blood pressure; DBP, diastolic blood pressure; CRP, C-reactive protein; WBC, white blood cell count; LY, lymphocyte count; MONO, monocyte count; NA, neutrophil absolute; EA, eosinophilic absolute; BA, basophilic absolute; Hgb, hemoglobin count; PLT count, platelet; A/G, albumin/globulin absolute; FFA, free fatty acids; TC, total cholesterol; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; IL-6, interleukin-6; IL-6R, interleukin-6 receptor; IL-1RA, Interleukin-1 receptor antagonist; HCY, homocysteine; D-D, D-dimer; ALB, albumin; Cr, creatinine.
Table 4 compares the stroke prevention strategies during hospitalization between CHIP and non-CHIP carriers. The results showed no significant differences in the medications used for treatment, including antiplatelet, anticoagulant, antihypertensive, lipid-regulating, or glucose-lowering drugs. Additionally, there were no significant differences between the two groups that underwent carotid artery stenting (CAS) or carotid endarterectomy (CEA).
Table 4. Comparison of the stroke prevention strategies during hospitalization between CHIP and non-CHIP carriers.
| Variables |
Total (N = 4,699) |
CHIP carriers (N = 180 [3.8%]) |
Non-CHIP carriers (N = 4,519 [96.2%]) |
P Value |
|---|---|---|---|---|
| Antiplatelet therapy | 4542 (96.7) | 175 (97.2) | 4367 (96.6) | 0.668 |
| Aspirin | 4136 (88.0) | 153 (85.0) | 3983 (88.1) | 0.204 |
| Clopidogrel | 2934 (62.4) | 109 (60.6) | 2825 (62.5) | 0.594 |
| Anticoagulation | 488 (10.4) | 19 (10.6) | 469 (10.4) | 0.939 |
| Statin drugs | 4533 (96.5) | 170 (94.4) | 4363 (96.5) | 0.134 |
| Glucose-lowering drugs | 1298 (27.6) | 48 (26.7) | 1250 (27.7) | 0.770 |
| Anti-hypertension | 2178 (46.4) | 86 (47.8) | 2092 (46.3) | 0.695 |
| CAS | 10 (0.2) | 10 (0.2) | 0.528 | |
| CEA | 1 (0.0) | 1 (0.0) | 0.842 |
carotid artery stenting, CAS; carotid endarterectomy, CEA
Association of CHIP Carriers with Recurrent Stroke
The associations between CHIP carriers and stroke recurrence at three months and one year in patients with ischemic stroke, stratified by the intracranial atherosclerotic burden, are shown in Table 5 . In total, 305 (6.5%) and 445 (9.5%) patients experienced stroke recurrence at three months and one year, respectively. After classifying the patients according to ICAS, at both ICAS ＞0 and ICAS=0, CHIP carriers had a higher rate of stroke recurrence at three months compared to non-CHIP carriers, regardless of ICAS status (ICAS ＞0:8.9% versus 6.5%, ICAS=0:7.6% versus 6.3%). In an unadjusted model, CHIP carriers were associated with an increased risk of recurrent stroke in patients with ICAS ＞0 at three months. However, no significant difference was observed (hazard ratio [HR] 1.37, 95% confidence interval [CI] 0.70–2.68, P=0.36). In the IPTW model, CHIP carriers with an ICAS degree ＞0 were associated with an increased risk of recurrent stroke (adjusted HR 2.26, 95% CI [1.30–3.95], P=0.004). However, the P-value for the interaction was not statistically significant. When CHIP and non-CHIP carriers were divided into two groups based on whether the AS score was higher than the median, that is, an AS score of ≥ 1 or ＜1, the rates of stroke recurrence in CHIP carriers were higher than those in non-CHIP carriers (AS score ≥ 1:7.5% versus 6.8%; AS score ＜1:10% versus 5.7%). In the IPTW model, CHIP carriers with AS scores ≥ 1 were associated with an increased risk of recurrent stroke (adjusted HR 1.83, 95% CI [1.06–3.19], P=0.03), while the P-value for the interaction was not statistically significant.
Table 5. Associations between CHIP carriers with a 3-month and 1-year stroke recurrence in deferent ICAS or Atherosclerosis Scores.
|
Total (N= 4699 [100%]) |
CHIP carriers (N= 180 [3.8%]) |
Non – CHIP carriers (N= 4519 [96.2%]) |
Unadjusted① | Model 1② | |||||
|---|---|---|---|---|---|---|---|---|---|
| HR (95%CI) | P value | P for Interaction | HR (95%CI) | P value | P for Interaction | ||||
| 3-months stroke recurrence | |||||||||
| ICAS= 0 | 131 (6.4) | 6 (7.6) | 125 (6.3) | 1.23 (0.54 2.80) | 0.617 | 1.17 (0.52 2.60) | 0.705 | ||
| ICAS ＞0 | 174 (6.6) | 9(8.9) | 165 (6.5) | 1.37 (0.70 2.68) | 0.358 | 0.22 | 2.26 (1.30 3.95) | 0.004 | 0.182 |
| AS ＜Median | 96 (5.9) | 6 (10) | 90 (5.7) | 1.83 (0.80 4.17) | 0.153 | 1.60 (0.71 3.59) | 0.254 | ||
| AS ≥ Median | 209 (6.8) | 9 (7.5) | 200 (6.8) | 1.10 (0.56 2.14) | 0.788 | 0.349 | 1.83 (1.06 3.19) | 0.032 | 0.782 |
| 1-year stroke recurrence | |||||||||
| ICAS= 0 | 189 (9.2) | 6 (7.6) | 183 (9.2) | 0.85 (0.38 1.91) | 0.685 | 0.81 (0.36 1.78) | 0.592 | ||
| ICAS ＞0 | 256 (9.7) | 14 (13.9) | 242 (9.5) | 1.47 (0.86 2.52) | 0.162 | 0.266 | 2.71 (1.77 4.16) | ＜.0001 | 0.008 |
| AS ＜Median | 137(8.4) | 6 (10) | 131 (8.3) | 1.27 (0.56 2.87) | 0.571 | 1.12 (0.50 2.50) | 0.779 | ||
| AS ≥ Median | 308 (10.1) | 14 (11.7) | 294 (10) | 1.17 (0.68 2.0) | 0.571 | 0.871 | 2.17 (1.42 3.32) | 0.0003 | 0.154 |
Unadjusted; Model1: age, sex, BMI, smoking, drinking, history (stroke, TIA, hypertension, diabetes, lipid, CHD, and MI), NIHSS score, and IL-6 level. “ICAS = 0” indicating no stenosis, “ICAS ＞0” indicating 0-99% stenosis or occlusion. Atherosclerosis Scores (AS) were used to evaluate the atherosclerosis burden, which was determined by the number and degree of steno-occlusion of the intracranial arteries.
For 1-year stroke recurrence since stroke onset, Table 5 shows that CHIP carriers with ICAS ＞0 had a significantly higher incidence of recurrent stroke than non–CHIP carriers (model 1: adjusted HR 2.71, 95% CI [1.77–4.16], P＜0.0001; P for interaction =0.008). CHIP carriers with an AS score ≥ 1 were associated with an increased risk of recurrent stroke in model 1 (adjusted HR 2.17, 95% CI [1.42–3.32], P=0.0003). However, the P-value for the interaction was not statistically significant.
Additionally, the association between the intracranial atherosclerotic burden and stroke recurrence within three months or one year only in CHIP carriers was evaluated. The results showed that those with “ICAS ＞0” tend to have a higher risk of stroke recurrence within three months or one year compared to those without vascular stenosis, but this trend is not statistically significant ( Supplementary Table 1 ) . Similar results were observed when evaluating AS ( Supplementary Table 2 ) .
Supplementary Table 1. Comparison of stroke recurrence risk at 3 months and 1 year among CHIP-carriers with different degrees of ICAS.
| CHIP Carriers (N = 180) |
ICAS ＞0 (N = 101) |
ICAS = 0 (N = 79) |
Unadjusted① | Model 1② | ||
|---|---|---|---|---|---|---|
| HR (95%CI) | P value | HR (95%CI) | P value | |||
| 3 months stroke recurrence | 9 (8.9) | 6 (7.6) | 1.15 (0.41 3.24) | 0.79 | 1.01 (0.31 3.28) | 0.99 |
| 1-year stroke recurrence | 14 (13.9) | 6 (7.6) | 1.8 (0.69 4.69) | 0.23 | 1.57 (0.54 4.61) | 0.41 |
① Unadjusted
② Model1: age, sex, BMI, smoking, drinking, history (stroke, TIA, hypertension, diabetes, lipid, CHD, and MI), NIHSS score, and IL-6 level. ICAS, Intracranial atherosclerotic stenosis; “ICAS = 0” indicating no stenosis, “ICAS ＞0” indicating 099% stenosis or occlusion.
Supplementary Table 2. Comparison of Stroke Recurrence Risk at 3 Months and 1 Year among CHIP-Carrying Patients with Different Degrees of AS③ .
| CHIP Carriers (N = 180) | AS ≥ Median (N = 120) | AS ＜Median (N = 60) | Unadjusted① | Model 1② | ||
|---|---|---|---|---|---|---|
| HR (95%CI) | P value | HR (95%CI) | P value | |||
| 3 months stroke recurrence | 9 (7.5) | 6 (10) | 0.72 (0.26 2.03) | 0.54 | 0.68 (0.21 2.24) | 0.53 |
| 1-year stroke recurrence | 14 (11.7) | 6 (10) | 1.13 (0.43 2.94) | 0.80 | 0.99 (0.33 3.01) | 0.99 |
① Unadjusted
② Model1: age, sex, BMI, smoking, drinking, history (stroke, TIA, hypertension, diabetes, lipid, CHD, MI), NIHSS score, and IL-6 level.
③ AS, Atherosclerosis Scores, to evaluate the atherosclerosis burden.
Discussion
In this study, we provided evidence of an association between CHIP and long-term risk of stroke recurrence in patients with ischemic stroke, which was found to be related to the degree of ICAS. In patients with a higher atherosclerotic burden, the presence of CHIP increased the risk of stroke recurrence one year after symptom onset. Our results suggest that detecting CHIP in patients with a higher atherosclerotic burden can be a helpful strategy for screening individuals at a high risk of long-term stroke recurrence.
We found that CHIP increased the risk of long-term stroke recurrence in the patients with ICAS. Stroke is a complex multifactorial disease in which unknown age-related factors play an important role. As a novel risk factor for atherosclerotic cardiovascular disease, CHIP has also been reported to be associated with an increased risk of stroke occurrence 1 , 5 , 20) . In addition, Qiu et al. provided evidence that somatic mutations contributing to CHIP increase the risk of short-term recurrent stroke in patients with first-ever AIS 7) . Our study has placed greater emphasis on assessing both the short-term and long-term recurrence risk in patients with different atherosclerotic burdens, while addressing the gap in understanding CHIP’s impact of CHIP on long-term stroke recurrence risk. This offers a new perspective on secondary prevention strategies for stroke.
In a recent study, CHIP identified in patients with AIS was associated with large-artery atherosclerosis stroke 6) . Atherosclerosis, a prevalent cause of ischemic stroke, can lead to stenosis of the internal carotid artery, serving as the underlying cause of 8–15% of ischemic strokes 21) . As an age-related and intimal inflammatory disease, the development of atherosclerosis likely requires low-density lipoproteins and the stimulation of inflammatory cells and factors, which could cause a locally impaired homeostatic function of the luminal endothelium 22) . Thus, atherosclerosis has the potential to gradually affect intracranial arterial beds, and persistent occlusive thrombi can provoke AIS 19) . Therefore, atherosclerosis significantly increases the risk of stroke and recurrent events. The association between ischemic symptoms and narrowing of the arterial lumen reminds researchers to assess the degree of intracranial arterial stenosis 23) . In a previous study, the degree of ICAS was evaluated to calculate AS, which can effectively reflect the risk of stroke 24) . However, a comparison of stroke recurrence risks among CHIP carriers with varying degrees of atherosclerotic burden showed that the impact of ICAS on 1-year stroke recurrence depends on the presence of CHIP. This finding highlights the importance of CHIP in influencing stroke recurrence.
Based on these findings, we identified a significant association between CHIP and atherosclerosis. As previously mentioned, experimental results showed that Tet2 knockout mice had larger atherosclerotic lesions in the aorta than the controls. In addition, analyses of macrophages from Tet2 knockout mice showed elevated expression of several chemokines, cytokines, and cytokine genes that contribute to atherosclerosis 3) . The effect of CHIP on accelerating atherosclerosis may be related to the interaction between inflammatory factors. In our study, we found that CHIP carriers had higher hs-CRP, IL-6, and IL-1RA levels than non-CHIP carriers, which is consistent with the results of previous research 1 , 5) . Therefore, the results demonstrate that CHIP may accelerate atherosclerotic lesions in patients through long-term chronic regulation of inflammatory factors, thus leading to an increased risk of stroke recurrence.
Limitations
Our study was associated with some limitations. First, as a multicenter study, patients were recruited from various hospitals, and the imaging tests were completed inconsistently, which may have led to subtle differences in the neuroimaging data collected. However, imaging data were evaluated by professionals according to a unified standard. Second, because of the limited number of patients and the number of recurrent cases, calculations could not be supported to further distinguish between the anterior and posterior circulation.
Conclusion
CHIP is associated with a long-term risk of stroke recurrence in patients with AIS and a higher AS burden. It would be helpful to identify CHIP carriers among patients with a higher atherosclerotic burden to identify those at high risk for long-term recurrent stroke.
Sources of Funding
This study was supported by grants from the National Natural Science Foundation of China (grant number 82171270), the Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences (2019-I2M-5-029), and the Natural Science Foundation of Beijing Municipality (Z200016).
Author Contributions:
Jiaxu Weng: Conceptualization (equal); data curation (equal); writing – original draft (lead). Xin Qiu: Conceptualization (equal); investigation (lead); writing – original draft (equal). Yingyu Jiang: Formal analysis (equal). Hongqiu Gu: Methodology (lead). Xia Meng: Conceptualization (equal); writing, review, and editing (equal). Xingquan Zhao: Writing, reviewing, and editing (equal). Yongjun Wang: Conceptualization (equal); writing, review, and editing (equal). Zixiao Li: Conceptualization (equal); writing, review, and editing (equal). All authors have read and approved the final manuscript.
Competing Interests:
The authors have no relevant financial or non-financial interests to disclose.
Data Availability:
Data supporting the findings of this study are available upon request from the corresponding author.
Ethics Approval:
The Ethics Committee of Beijing Tiantan Hospital approved the study protocol (KY2015-001-01).
Consent to Participate:
Informed consent was obtained from all participants included in the study.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
Data supporting the findings of this study are available upon request from the corresponding author.