title: Nonobstructive Versus Obstructive Coronary Artery Disease in Acute Coronary Syndrome: A Meta-Analysis.
abstract: Differences in prognosis and baseline clinical presentation have been documented among patient with acute coronary syndrome and coronary artery disease with obstructive (ObCAD) or nonobstructive arteries (NObCAD), but the rates of events largely varied across single studies. We carried out a meta-analysis to compare the clinical presentation and prognosis of NObCAD versus ObCAD acute coronary syndrome patients, as well as of the subjects with zero versus mild occlusion.
  
  
  
  Searches were made in MedLine, EMBASE, Cochrane databases, and proceedings of international meetings up to June 30, 2015. We compared the risk of events of NObCAD versus ObCAD patients using random-effect meta-analyses. We also performed meta-analyses to estimate the yearly or monthly outcome rates in each single group. In NObCAD and ObCAD patients, respectively, the combined yearly rates were as follows: 2.4% versus 10.1% (all-cause mortality); 1.2% versus 6.0% (myocardial infarction), 4.0% versus 12.8% (all-cause mortality plus myocardial infarction), 1.4% versus 5.9% (cardiac death), and 9.2% versus 16.8% (major cardiovascular events). In the studies directly comparing NObCAD versus ObCAD, all of the above outcomes were significantly less frequent in NObCAD subjects (with risk ratios ranging from 0.33 to 0.66). No differences in any outcome rate were observed between mild occlusion (1-49% stenosis) and zero occlusion patients.
  
  
  
  NObCAD in patients with acute coronary syndrome has a significantly lower cardiovascular risk at baseline and a subsequent lower likelihood of death or main cardiovascular events. However, these subjects are still at high risk for cardiovascular mortality and morbidity, suggesting potential undertreatment and calling for specific management.
authors.affiliation: Department of Specialised, Experimental and Diagnostic Medicine, University of Bologna, Italy carmine.pizzi@unibo.it.
authors.forename: Carmine
authors.initials: C
authors.lastname: Pizzi
authors.affiliation: Department of Specialised, Experimental and Diagnostic Medicine, University of Bologna, Italy.
authors.forename: Borejda
authors.initials: B
authors.lastname: Xhyheri
authors.affiliation: Department of Specialised, Experimental and Diagnostic Medicine, University of Bologna, Italy.
authors.forename: Grazia Maria
authors.initials: GM
authors.lastname: Costa
authors.affiliation: Cardiology Department, Private Hospital "L. Pierangeli", Pescara, Italy.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Faustino
authors.affiliation: Department of Medicine, University of Chieti, Italy.|Local Health Unit of Pescara, Italy.|Department of Community Health and Social Medicine, Sophie Davis School of Biomedical Education, The City College of New York, New York, NY.
authors.forename: Maria Elena
authors.initials: ME
authors.lastname: Flacco
authors.affiliation: Department of Public Health Sciences, University of Turin, Torino, Italy.
authors.forename: Maria Rosaria
authors.initials: MR
authors.lastname: Gualano
authors.affiliation: Department of Medicine, University of Chieti, Italy.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Fragassi
authors.affiliation: Department of Specialised, Experimental and Diagnostic Medicine, University of Bologna, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Grigioni
authors.affiliation: Local Health Unit of Pescara, Italy.|Regional Healthcare Agency of Abruzzo, Pescara, Italy.|Department of Medicine Sciences, University of Ferrara, Italy.
authors.forename: Lamberto
authors.initials: L
authors.lastname: Manzoli
mesh_terms: D054058:Acute Coronary Syndrome / Q000150:complications* / Q000401:mortality; D002318:Cardiovascular Diseases / Q000401:mortality; D003324:Coronary Artery Disease / Q000150:complications* / Q000401:mortality; D054059:Coronary Occlusion / Q000150:complications / Q000401:mortality; D005260:Female; D006801:Humans; D008297:Male; D011379:Prognosis; D012307:Risk Factors
keywords: acute coronary syndrome; acute myocardial infarction; angina pectoris; coronary artery disease; epicardial vessel stenosis; meta‐analysis; microcirculation; nonobstructive coronary artery disease; obstructive coronary artery disease; prognosis