This heart valve surgery risk calculator determines in-hospital mortality in the case of patients with aortic and/or mitral cardiac surgery based on preoperative criteria. The text below the form contains information on the original study, the scores involved and subsequent mortality risk percentages.
How does this heart valve surgery risk calculator work?
This health tool predicts in-hospital mortality in patients undergoing heart valve surgery based on a series of clinical predictors.
The original study and validation (Simple Risk Stratification Model for Heart Valve Surgery) were constructed on a national database of 32,502 patients with data collected routinely from 30 different institutions over a period of 8 years.
As the first risk model for in-hospital mortality for aortic and/or mitral heart valve patients, it accounts for both CABG and none.
The following table introduces the preoperative characteristics that can be found in the heart valve surgery risk calculator, their selections and the corresponding points.
| Preoperative Characteristic | Item | Score |
| Age (years) | 50–59 | 1 |
| 60–69 | 2 | |
| 70–79 | 4 | |
| >79 | 5 | |
| Gender | Female | 1 |
| BMI | <20 kg/m2 | 2 |
| Valve operation | Mitral | 1 |
| Aortic and mitral | 2 | |
| Concomitant tricuspid surgery | Yes | 3 |
| Concomitant CABG surgery | Yes | 2 |
| Renal failure | Creatinine >200 µmol/L | 3 |
| With dialysis | 5 | |
| Arrhythmias | Atrial fibrillation/ heart block | 1 |
| Ventricular tachycardia/fibrillation | 2 | |
| Hypertension | Yes | 1 |
| Diabetes | Yes | 1 |
| Ejection fraction (%) | 30–50 | 1 |
| <30 | 4 | |
| Surgical priority | Urgent | 2 |
| Emergency | 7 | |
| Prior cardiac operation | 1 | 3 |
| ≥2 | 4 |
The strongest group of predictors are operative priority followed by renal failure, age and then operation sequence.
The below table introduces the total risk scores from 0 to 27 (maximum value obtained in the validation study).
| Total Risk Score | Risk of in-hospital death (%) | Total Risk Score | Risk of in-hospital death (%) |
| 0 | 0.2 | 14 | 20.2 |
| 1 | 0.4 | 15 | 23.5 |
| 2 | 0.6 | 16 | 26.7 |
| 3 | 1 | 17 | 30.1 |
| 4 | 1.4 | 18 | 33.4 |
| 5 | 2.1 | 19 | 36.6 |
| 6 | 3 | 20 | 39.7 |
| 7 | 4.1 | 21 | 42.6 |
| 8 | 5.5 | 22 | 45.5 |
| 9 | 7.3 | 23 | 48.1 |
| 10 | 9.3 | 24 | 50.6 |
| 11 | 11.7 | 25 | 52.9 |
| 12 | 14.3 | 26 | 55 |
| 13 | 17.2 | 27 | 57 |
The total risk scores range from 0 to 39 and each risk prediction in % can be obtained from the risk score (S) by following these two formulas:
■ Log odds = 1.36 − 1.75 × exp(1.45 − 0.0716 × S)
■ Risk of in-hospital death (%) = 100/[1 + exp(−Log odds)]
The study also lists other mortality predictors such as active endocarditis, stenosis or regurgitation. Although statistically relevant, these predictors were not considered sufficiently strong.
Heart valve surgery guidelines
Heart valve surgeries make for the second most common type of cardiac surgery and carry an in-hospital mortality of 4-8%. The functioning of the valve in question is usually tested through a transesophogeal echo. The most commonly repaired valve is the mitral one.
In some cases, there is the possibility of minimally invasive heart valve surgery which is performed through small incisions and aims to reduce blood loss and the length of recovery days in hospital.
In cases when the patient is not well enough to support cardiac surgery, a transcatheter aortic valve implantation procedure may take place instead.
Surgery is performed to make repairs, recover function, help preserve heart muscles, as well as to allow the patient to lower the dose or come off anticoagulant medication.
The following are the types of valve repair procedures:
■ Commissurotomy – helps widen the valve opening in case of fuses or flaps.
■ Decalcification – helps remove calcium deposits in order to recover valvular function.
■ Chordal transfer – applied in case of prolapse of one leaflet of the mitral valve.
■ Reshape leaflets (Quandrangular resection) – applied in case of floppy leaflets.
■ Patching leaflets – covering of tears and holes in leaflets with tissue patches.
Valve replacement surgery occurs when repairs cannot be performed and a new valve, either mechanical, biological or allograft, is attached to the annulus of the original valve. Tissue valves usually have some artificial parts in their structure.
Recovery depends on patient characteristics and the type of procedure but most patients are released within a week. Average full recovery takes place in 2 to 3 months.
One of the main complications after valve surgery is the occurrence of endocarditis, when the valve becomes infected.
Most patients are also required to start on a therapy with anticoagulants, usually warfarin in order to prevent the forming of blood clots.
References
1) Ambler G, Omar RZ, Royston P, Kinsman R, Keogh BE, Taylor KM. (2005) Generic, simple risk stratification model for heart valve surgery. Circulation; 112(2):224-31.
2) Edwards FH, Peterson ED, Coombs LP, DeLong ER, Jamieson WR, Shroyer ALW, Grover FL. (2001) Prediction of operative mortality after valve replacement surgery. J Am Coll Cardiol; 37(3):885-92.
3) Jamieson WR, Edwards FH, Schwartz M, Bero JW, Clark RE, Grover FL. (1999) Risk stratification for cardiac valve replacement. National Cardiac Surgery Database. Database Committee of The Society of Thoracic Surgeons. Ann Thorac Surg; 67(4):943-51.
4) Parsonnet V, Dean D, Bernstein AD. (1989) A method of uniform stratification of risk for evaluating the results of surgery in acquired adult heart disease. Circulation; 79(6 Pt 2):I3-12.
04 Oct, 2016