Table 3. Top three attributes according to contribution level of the models.

	C4.5	ID3	Logistic regression analysis	Logistic regression analysis
	Dataset 1	Dataset 2	Dataset 1	Dataset 2
1	Pulmonary hypertension*	Recent myocardial infarct	Pulmonary hypertension	Surgery on thoracic aorta
2	Recent myocardial infarct	Other than isolated CABG	Age	Critical preoperative state
3	Surgery on thoracic aorta	Age	Previous cardiac surgery	Recent myocardial infarct
* It is thought that the initial presence of a large number of missing values of pulmonary hypertension has an effect on the obtained result; CABG: Coronary artery bypass grafting.