Associations of clonal haematopoiesis with recurrent vascular events and death in patients with incident ischemic stroke.

Clonal hematopoiesis (CH) is common among older people and associated with an increased risk of atherosclerosis, inflammation, and shorter overall survival. Age and inflammation are major risk factors for ischemic stroke, yet the association of CH with risk of secondary vascular events and death is unknown. We investigated CH in peripheral blood DNA from 581 patients with first-ever ischemic stroke from the Prospective Cohort with Incident Stroke-Berlin study (PROSCIS-B) using error-corrected targeted sequencing. The primary composite endpoint (CEP) consisted of recurrent stroke, myocardial infarction, and all-cause mortality. 348 somatic mutations with a variant allele frequency ≥ 1% were identified in 236/581 patients (41%). CH was associated with large-artery atherosclerosis stroke (P = 0.01) and white matter lesion (P < 0.001). CH-positive patients showed increased levels of pro-inflammatory cytokines such as IL-6, IFN-γ, hsCRP, and VCAM-1. CH-positive patients had a higher risk for the primary CEP (HR: 1.55, 95%-CI 1.04 - 2.31, P = 0.03), which was more pronounced in patients with larger clones. CH clone size remained an independent risk factor (HR 1.30, 95%-CI 1.04 - 1.62, P = 0.022) in multivariable Cox regression. While our data show that in particular larger and TET2- or PPM1D-mutated clones are associated with increased risk of recurrent vascular events and death, this risk is partially mitigated by a common germline variant of the IL-6 receptor (IL-6R p.D358A). The CH mutation profile is accompanied by a pro-inflammatory profile opening new avenues for preventive precision medicine approaches to resolve the self-perpetuating cycle of inflammation and clonal expansion.