Acoustic cardiography to improve detection of coronary artery disease with stress testing

Table 1 Baseline clinical characteristics

	All (n = 59)	No CAD by angiography (n = 25)	CAD by angiography (n = 34)
Baseline characteristics
Age (yr)	62 ± 11	61 ± 13	62 ± 10
History of angina	37 (63)	13 (52)	24 (71)
Echo ejection fraction (%)	59 ± 11	59 ± 7	59 ± 12
Invasive LV end-diastolic pressure (mmHg)	15 ± 7	14 ± 6	15 ± 8
Baseline heart rate (beats/min)	67 ± 12	66 ± 11	69 ± 13
Maximum heart rate during ETT (beats/min)	129 ± 19	137 ± 19	122 ± 17
Baseline ST depression	12 (20)	2 (8)	10 (29)
Maximum workload during ETT (W)	132 ± 41	149 ± 43	119 ± 34
Heart rate × SBP at rest (mmHg/min)	9357 ± 2397	8991 ± 2314	9634 ± 2457
Heart rate × SBP at peak exercise (mmHg/min)	25 790 ± 5740	27 870 ± 5070	24 210 ± 5780
Rise in double pressure product (factor)	2.9 ± 0.9	3.3 ± 1.0	2.6 ± 0.7
Baseline SBP (mmHg)	138 ± 24	137 ± 22	140 ± 27
Maximum SBP during ETT (mmHg)	200 ± 28	203 ± 25	197 ± 29
Symptomatic ST depression (mm)	1.98 ± 0.55	NA	1.98 ± 0.55
Silent ST depression (mm)	2.05 ± 1.23	NA	2.05 ± 1.23
LBBB	1 (2)	0 (0)	1 (3)
RBBB	3 (5)	2 (8)	1 (3)
Acoustic cardiographic S3 detected	1 (2)	0 (0)	1 (3)
Acoustic cardiographic S4 detected	6 (10)	1 (4)	5 (14)
CAD risk factors
High cholesterol (> 5.2 mmol/L)	41 (69)	18 (72)	23 (68)
Stage 1 blood pressure (SBP 140-159, DBP 90-99 mmHg)	18 (30)	7 (28)	11 (32)
Stage 2 blood pressure (SBP > 160, DBP > 100 mmHg)	14 (24)	5 (20)	9 (26)
Diabetes (fasting glucose > 6.1)	5 (8)	2 (8)	3 (9)
Body mass index (kg/m2)
Overweight (25-29.9)	29 (49)	11 (44)	18 (53)
Obese (> 30)	14 (24)	5 (20)	9 (26)
Age (men > 45 yr, women > 55 yr)	41 (69)	17 (68)	24 (71)
Prior myocardial infarction	13 (22)	5 (20)	8 (23)

Values are given either as mean ± SD for continuous parameters or as n (percentage) for dichotomous variables. Prior myocardial infarction based on medical history, echocardiography or angiography. SBP: Systolic blood pressure; DBP: Diastolic blood pressure; NA: Not applicable; CAD: Coronary artery disease; ETT: Exercise tolerance testing; LBBB: Left bundle branch block; RBBB: Right bundle branch block; LV: Left ventricular.

Table 2 Medical therapy in patients with and without CAD by angiography

Condition	All (n = 59)	No CAD by angiography (n = 25)	CAD by angiography (n = 34)
Hyperlipidemia	23 (70)	7 (86)	16 (62.5)
Hypertension	30 (87)	12 (92)	18 (83)
Diabetes	5 (20)	2 (0)	3 (33)

Values are given as n (percentage) of the group being treated with drug therapy.

Table 3 Extent of angiographic CAD

	All (n = 34)	S4 at Max HR (n = 18)	ST depression (n = 10)	S4 or ST depression (n = 23)
Left main artery	2 (6)	1 (6)	1 (10)	2 (9)
Left anterior descending	24 (71)	15 (83)	8 (80)	20 (87)
Right circumflex artery	17 (50)	10 (56)	7 (70)	13 (57)
Right coronary artery	24 (71)	10 (56)	6 (60)	13 (57)
One-vessel disease	13 (38)	7 (39)	3 (30)	8 (35)
Two-vessel disease	10 (29)	5 (28)	2 (20)	6 (26)
Three-vessel disease	11 (32)	6 (33)	5 (50)	9 (39)
Invasive ejection fraction (%)	65 ± 11	67 ± 11	70 ± 12	67 ± 11
Invasive LVEDP (mmHg)	15 ± 8	18 ± 9	11 ± 8	15 ± 9

Values are given either as mean ± SD for continuous parameters or as n (percentage) for dichotomous variables.

Table 4 Diagnostic performances of ECG versus heart sounds in 59 patients (40 men, 19 women)

Parameter	Group	Sensitivity (%)	Specificity (%)	PLR	NLR
ST depression	All	29 (CI 17-46)	92 (CI 75-98)	3.68 (CI 0.88-15.3)	0.77 (CI 0.60-0.98)
ST depression	Men	28 (CI 14-48)	93 (CI 70-99)	4.2 (CI 0.57-30.9)	0.77 (CI 0.58-1.02)
ST depression	Women	33 (CI 12-65)	90 (CI 60-98)	3.33 (CI 0.42-26.58)	0.74 (CI 0.45-1.23)
S4 present	All	53 (CI 37-69)	92 (CI 75-98)	6.62 (CI 1.7-25.9)	0.51 (CI 0.35-0.74)
S4 present	Men	52 (CI 34-70)	93 (CI 70-99)	7.8 (CI 1.13-53.8)	0.51 (CI 0.34-0.79)
S4 present	Women	56 (CI 27-81)	90 (CI 60-98)	5.56 (CI 0.79-39.01)	0.49 (CI 0.23-1.06)
S4 or ST-depression	All	68 (CI 51-81)	84 (CI 65-94)	4.23 (CI 1.7-10.7)	0.39 (CI 0.23-0.65)

PLR: Positive likelihood ratio; NLR: Negative likelihood ratio.