• For our first objective (i.e., the incidence of major perioperative vascular events) our primary outcome is major vascular events (i.e., a composite of vascular death, nonfatal myocardial infarction, nonfatal cardiac arrest, and nonfatal stroke) [ Time Frame: 30 days post surgery. ] [ Designated as safety issue: No ]
  

• For our second objective (i.e., the optimal clinical model to predict major perioperative vascular events) our primary and only outcome is major vascular events. [ Time Frame: 30 days after surgery. ] [ Designated as safety issue: No ]
  
• For our third objective (i.e., the proportion of patients with perioperative MIs that may go undetected without perioperative troponin monitoring) our outcome is myocardial infarction that probably or possibly would have gone undetected [ Time Frame: 30 days after surgery. ] [ Designated as safety issue: No ]
  
• For our fourth objective (i.e., the relationship between postoperative troponin measurements and the 1 year risk of vascular death) our outcomes are vascular death, and major vascular events (i.e., vascular death, MI, cardiac arrest, stroke) [ Time Frame: 1 year after surgery ] [ Designated as safety issue: No ]
  

The increase in elderly patients undergoing surgery, the change in the invasiveness of some surgical interventions, limitations in the methodology and generalizability of previous research, and the VISION Pilot Study results highlight uncertainty about the current incidence of major vascular events and the optimal clinical risk estimation model to predict these events in patients undergoing noncardiac surgery. There is promising but inconclusive preliminary evidence that troponin measurements after surgery may allow physicians to avoid missing perioperative myocardial infarctions and may predict mortality and major vascular events in the first year following surgery. These considerations provide the impetus for the large, adequately powered, multicentre, international, prospective cohort study.

We will to determine the incidence of major vascular events, the optimal clinical model to predict major perioperative vascular events, and the extent to which troponin measurements post surgery can identify myocardial infarctions that are likely to go unrecognized and predict vascular death at 1 year. We call this study the Vascular events In noncardiac Surgery patIents cOhort evaluatioN (VISION) Study.

The VISION Study is a prospective cohort study of 40,000 patients who are > 45 years of age, undergoing noncardiac surgery requiring overnight hospital admission, and receiving a general or regional anesthetic. Hospitals (including both university and non-university hospitals) in several countries around the world will recruit patients, over a 2 year period. Study personnel will evaluate patients prior to surgery, follow patients throughout their hospitalization, and contact patients at 30 days and 1 year after surgery. All patients will have troponin T measured post surgery and on the first, second, and third days after surgery. Outcome adjudicators will adjudicate all major vascular events without knowledge of a patient's vascular risk factors.

We will also determine if there are associations between any preoperative or postoperative medications and major perioperative vascular events. We will also determine if there are associations between any medications started after a major perioperative vascular event and vascular mortality 1 year after surgery. We will evaluate the 1 year risk of stroke in patients who do and do not develop atrial fibrillation after surgery and if there is an association with antiplatelet or warfarin therapy. We will measure N-terminal prohormone brain natriuretic peptide (NT-proBNP) in 8,000 - 10,000 patients prior to surgery and determine if NT-proBNP is an independent predictor of major perioperative vascular events. We will determine the incidence of perioperative new acute renal failure requiring dialysis and pneumonia and develop models to predict these events.