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Pulmonary arterial hypertension (PAH) is a severe, progressive disease characterized by elevated pulmonary arterial pressure and increased vascular resistance. This hemodynamic strain forces the right ventricle to pump against a high-pressure system, ultimately leading to right-sided heart failure and death. The pathogenesis of PAH involves a complex interplay of vasoconstriction, chronic inflammation, and pathological remodeling of the pulmonary vessel walls-specifically hypertrophy of the smooth muscle and intimal layers-driven by molecular imbalances and genetic predispositions. Current FDA-approved therapies primarily manage symptoms through vasodilation but fail to directly target the underlying vascular remodeling. Imatinib, a tyrosine kinase inhibitor originally developed for oncological indications, has emerged as a potential disease-modifying agent for PAH. By inhibiting platelet-derived growth factor receptors (PDGFR), imatinib targets the aberrant proliferation of smooth muscle cells, offering a mechanism to potentially reverse or arrest vascular remodeling. Clinical trials, including the IMPRES study, have demonstrated encouraging hemodynamic improvements in patients with severe PAH refractory to standard therapies. However, systemic safety concerns and dose-dependent adverse reactions have limited its clinical approval. This review examines the pharmacological rationale for imatinib, its impact on vascular structure, and the safety signals observed in long-term studies. Furthermore, it discusses emerging strategies, such as inhaled formulations and pharmacogenetic approaches (e.g., the PIPAH study), aimed at enhancing the efficacy-to-safety ratio of kinase inhibitors to improve long-term outcomes for patients with PAH.