Background: Plaques with a large necrotic core or lipid pool and thin-cap fibroatheroma manifest as attenuated plaques on intravascular ultrasound (IVUS). Their impact on TIMI grade flow and clinical outcomes remains undefined. We performed a systematic review and meta-analysis to summarize the association between attenuated plaque and distal embolization and clinical outcomes of coronary artery disease (CAD) from pooled data of published eligible cohort studies. Methods: We searched the literature on TIMI grade flow and clinical outcomes on PubMed, Ovid, EMBASE, the Cochrane Library, CNKI and WanFang databases. Study heterogeneity and publication bias were estimated. Results: A total of 3,833 patients were enrolled in nine studies. Five studies investigated TIMI grade flow and attenuated plaques. They revealed no difference in TIMI grade flow before percutaneous coronary intervention (PCI) between the attenuated and non-attenuated plaque group (RR = 1.25; 95% CI: 0.65 to 2.41; P=0.50). After balloon dilation and stent implantation, the incidence of TIMI 0 similar to 2 grade flow in the attenuated plaque group was statistically significant higher than that of the non-attenuated plaque group (RR = 4.73; 95% CI: 3.03 to 7.40; P<0.001). Five other studies investigated major cardiovascular events (MACEs) and attenuated plaques and found no difference in MACE rates within three years of follow up. Conclusions: Our study presents the evidence that plaque with ultrasound signal attenuation would induce slow/no reflow phenomenon and distal embolization during PCI, but this appearance has no impact on MACE rates within three years.