modality of treatment. Those treated with mechanical thrombectomy with or without bridging IV-tPA composed the MT group. Patients treated with medical therapy alone with or without IV-tPA composed the standard medical treatment (SMT) group. Results A total of 7 articles were included in final analysis. Only 2 studies had comparable data between MT and SMT. A total of 150 patients were treated with MT and 213 with SMT. Patients treated with MT had significantly lower mean age (MT, 70.7 years vs SMT, 73.5 years; P=0.0007), higher mean/median NIHSS at presentation (MT, 7.4 vs SMT, 6.6; P=0.017) and longer time from onset of symptoms to treatment (MT, 230.3 minutes vs SMT, 154.1 minutes; P<0.0001). Intravenous alteplase was given to 45.3% of patients treated with MT and 53.1% of patients treated with SMT (P=0.152). The MT group was associated with a significantly higher rate of patients with occluded P1 segment (MT, 25.4% vs SMT, 14.5%; P=0.012) and significantly lower rate of patients with occluded P2 segment (MT, 63.3% vs SMT, 75.8%; P=0.012), while the rate of patients with occluded P3 segment did not differ between the two groups (MT, 11.3% vs SMT, 10.2%; P=0.741). The rate of good outcome was significantly higher in patients treated with MT than in those treated with SMT (MT, 68.5% vs SMT, 55.3%; P=0.014). There was no significant difference in the rates of sICH (MT, 3.9% vs SMT, 3%, P=0.568) and mortality (MT, 11.8% vs SMT, 12.4%, P=0.891). Good outcome significantly favored MT (OR, 1.78; 95% CI, 1.11 -2.85), while sICH and mortality did not favor any modality. Conclusions Our systematic review demonstrated the scarcity of available studies focusing on aPCAO in literature and complete absence of prospective comparison between MT and medical therapy alone. Our pooled analysis comparing treatment modalities demonstrated better odds of good outcome in patients treated with MT in comparison to SMT, while there was no difference in sICH and mortality. However, significant differences in the characteristics of patients among the treatment groups, such as age, NIHSS, occluded segment of the PCA and time from onset of symptoms to treatment, highlight the need of further studies with comparable data.
