Table 1

Patient characteristics and operative variables before and after propensity score matching

	Before matching							After matching
	Overall		Biological		Mechanical			Overall		Biological		Mechanical
	(n=3862)		(n=1945)		(n=1917)			(n=2362)		(n=1181)		(n=1181)
Continuous variables
	Mean	SD	Mean	SD	Mean	SD	Δ (%)	Mean	SD	Mean	SD	Mean	SD	Δ (%)
Age (years)	73.0	4.9	74.8	4.7	71.2	4.4	79.5	72.9	4.3	73.0	4.3	72.7	4.4	6.3
BMI	25.9	4.6	25.7	4.7	26.1	4.6	−7.4	25.9	4.7	25.9	4.7	25.9	4.7	0.9
BMI²	691.1	264.8	682.7	267.7	699.7	261.7	−6.4	691.4	264.6	692.5	259.4	690.2	269.8	0.8
Categorical and dichotomous variables
	n	%	n	%	n	%	Δ (%)	n	%	n	%	n	%	Δ (%)
Female	2244	58.1	1095	56.3	1149	59.9	−7.4	1377	58.3	696	58.9	681	57.7	2.6
Angina (CCS grade)
Class 0	2352	60.9	1191	61.2	1161	60.6	1.4	1438	60.9	723	61.2	715	60.5	1.4
Class I	608	15.7	283	14.6	325	17.0	−6.6	367	15.5	189	16.0	178	15.1	2.6
Class II	527	13.6	265	13.6	262	13.7	−0.1	332	14.1	162	13.7	170	14.4	−1.9
Class III	278	7.2	157	8.1	121	6.3	6.8	166	7.0	80	6.8	86	7.3	−2.0
Class IV	97	2.5	49	2.5	48	2.5	0.1	59	2.5	27	2.3	32	2.7	−2.7
IV nitrates	54	1.4	27	1.4	27	1.4	−0.2	35	1.5	14	1.2	21	1.8	−4.9
Dyspnoea (NYHA grade)
Class I	343	8.9	187	9.6	156	8.1	5.2	213	9.0	105	8.9	108	9.1	0.9
Class II	1140	29.5	591	30.4	549	28.6	3.8	688	29.1	346	29.3	342	29.0	0.7
Class III	1935	50.1	945	48.6	990	51.6	−6.1	1188	50.3	594	50.3	594	50.3	0.0
Class IV	444	11.5	222	11.4	222	11.6	−0.5	273	11.6	136	11.5	137	11.6	−0.3
Neurological dysfunction	114	3.0	53	2.7	61	3.2	−2.7	65	2.8	34	2.9	31	2.6	1.6
Diabetes	469	12.1	243	12.5	226	11.8	2.2	290	12.3	149	12.6	141	11.9	2.1
Atrial fibrillation	2001	51.8	827	42.5	1174	61.2	−38.1	1244	52.7	620	52.5	624	52.8	−0.7
History of hypertension	1919	49.7	1048	53.9	871	45.4	16.9	1197	50.7	596	50.5	601	50.9	−0.8
Pulmonary hypertension	516	13.4	251	12.9	265	13.8	−2.7	316	13.4	164	13.9	152	12.9	3.0
Previous MI	482	12.5	279	14.3	203	10.6	11.4	294	12.4	148	12.5	146	12.4	0.5
Creatinine >200 μmol/L	93	2.4	67	3.4	26	1.4	13.7	49	2.1	26	2.2	23	1.9	1.8
Chronic pulmonary disease	605	15.7	330	17.0	275	14.3	7.2	360	15.2	180	15.2	180	15.2	0.0
Extracardiac arteriopathy	218	5.6	127	6.5	91	4.7	7.7	130	5.5	65	5.5	65	5.5	0.0
Ejection fraction
Good (LVEF >50%)	2590	67.1	1265	65	1325	69.1	−8.7	1593	67.4	803	68	790	66.9	2.3
Fair (LVEF 30–50%)	1109	28.7	595	30.6	514	26.8	8.4	675	28.6	332	28.1	343	29.0	−2.1
Poor (LVEF<30%)	163	4.2	85	4.4	78	4.1	1.5	94	4.0	46	3.9	48	4.1	−0.9
Urgent	700	18.1	404	20.8	296	15.4	13.9	420	17.8	209	17.7	211	17.9	−0.4
Critical preoperative state	108	2.8	61	3.1	47	2.5	4.2	61	2.6	29	2.5	32	2.7	–1.6
Haemodynamics
Stenosis	658	17	225	11.6	433	22.6	−29.6	391	16.6	189	16.0	202	17.1	−3.0
Regurgitation	2432	63.0	1393	71.6	1039	54.2	36.7	1486	62.9	747	63.3	739	62.6	1.4
Mixed	772	20.0	327	16.8	445	23.2	−16.0	485	20.5	245	20.7	240	20.3	1.0
Active infective endocarditis	125	3.2	76	3.9	49	2.6	7.6	78	3.3	40	3.4	38	3.2	0.9
TV repair	395	10.2	246	12.6	149	7.8	16.1	238	10.1	122	10.3	116	9.8	1.7
CABG	1330	34.4	743	38.2	587	30.6	16.0	780	33.0	384	32.5	396	33.5	−2.2

Δ, standardised difference; BMI, Body Mass Index; CABG, coronary artery bypass graft; CCS, Canadian Cardiovascular Society; LVEF, left ventricular ejection fraction; MI, myocardial infarction; NYHA, New York Heart Association; TV, tricuspid valve.