Table 1 Model variable definitions

Age

Patient age at the time of surgery

Gender

Male or Female

Body mass index

Calculated in kilograms and centimeters.

Diabetes

Any history of Diabetes Mellitus, regardless of duration

Pre-op Afib

Any previously documented history of Atrial Fibrillation

COPD

Any preivous documented history of Chronic Obstructive Pulmonary Disease

CVD

Any Transient Ischemic Attack, Cerebrovascular Accident/Stroke, history of cerebrovascular surgery, or any carotid disease.

PVD

Whether the patient has Peripheral Vascular Disease, as indicated by claudication; amputation for arterial insufficiency; aorto-iliac occlusive disease reconstruction; peripheral vascular bypass surgery, angioplasty, or stent; documented AAA.

Frailty

Any deficiency in the Katz index of Activities of Daily Living (independence in feeding, bathing, dressing, transferring, toileting, and urinary continence), as well as independence in ambulation (no walking aid or assist required) or any clear evidence of a previous diagnosis of dementia by a physician.

EF<40

Ejection fraction measured less than 40% by any modality.

NYHA (I-IV)

New York Heart Association Class. I = Patients with cardiac disease but without limitation of physical activity. II = Patients with cardiac disease resulting in slight limitation of physical activity (fatigue, palpitations, dyspnea, or anginal pain). III = Patients with cardiac disease resulting in marked limitation of physical activity. IV = Patients with cardiac disease resulting in inability to carry on any physical activity without discomfort. Symptoms of cardiac insufficiency or of the anginal syndrome may be present even at rest.

Hemoglobin

Most recent hemoglobin level prior to day of surgery.

Pre-op creatinine

Highest preop serum creatinine for this admission.

Redo sternotomy

Any history of previous surgery that traversed the anterior mediastinum.

Surigical priority

Elective [stable at home], in-house [requiring hospitalization until the time of surgery], urgent [requiring surgery within 24 hours to minimize further clinical deterioration], or emergent [no delay in surgery].

Procedure

Any Coronary artery bypass grafting, aortic valve replacement or repair with/without CABG, or Mitral valve replacement or repair with/without CABG.