Table 4. Cox-proportional hazard model of mid-term survival by procedure sub-groups.

Significant variables	HR	95% CI		P value (≤)
		Lower	Upper
Age (years)	1.064	1.032	1.096	0.001
Preoperative creatinine (mg/dL)	1.195	1.106	1.291	0.001
NYHA class III/IV	1.585	1.250	2.012	0.001
Chronic lung disease (vs. none)				0.007
Mild	1.213	0.738	1.996	0.446
Moderate	1.364	0.836	2.225	0.213
Severe	1.864	1.103	3.150	0.020
Previous cardiac surgery	1.277	1.004	1.626	0.047