Echocardiographic Normal Reference of Left Ventricular Contractile Reserve During Treadmill Exercise Stress Echocardiography in Healthy Chinese Adults – New Non-Sex-Specific Parameter for Left Ventricular Contractile Reserve Evaluation

Figures & data

Figure 1 LV LS analysis at rest (A) and postexercise (B). LV LS of base, middle and apex were all increased after exercise, especially the apex.

Abbreviation: LS, longitudinal strain.

Table 1 Characteristics of the Population

Parameters	Total (n=157), Mean±SD	Male (n=71), Mean±SD	Female (n=86), Mean±SD	P-value
Age (years)	45.3±13.0	44.6±13.5	45.8±12.6	0.561
Height (cm)	163.7±8.4	169.8±7.9	158.7±4.6	<0.001
Weight (kg)	61.4±12.0	68.7±12.1	55.4±8.0	<0.001
Body surface area (m2)	1.7±0.2	1.9±0.2	1.6±0.1	<0.001
Body mass index (kg/m2)	22.6±3.0	23.6±3.1	21.8±2.6	<0.001
HRrest (bpm)	93±15	93±15	92±15	0.620
HRpeak (bpm)	165±16	167±16	163±16	0.067
HRpeak/target HR (%)	96±7	97±6	95±7	0.087
SBPrest (mmHg)	124±16	128±16	119±15	<0.001
SBPpeak (mmHg)	168±23	176±24	161±18	<0.001
DBPrest (mmHg)	77±10	80±10	75±10	0.004
DBPpeak (mmHg)	78±13	78±13	78±12	0.906
Exercise duration (min)	8.7±1.7	9.1±1.9	8.5±1.8	0.031
METs (units)	9.6±1.7	9.9±1.7	9.3±1.7	0.029

Abbreviations: HR, heart rate; SBP, systolic blood pressure; DBP, diastolic blood pressure; METs, metabolic equivalents.

Table 2 Conventional Treadmill Exercise Stress Echocardiographic Parameters of the Left Ventricle

Parameters	Total, Mean±SD	Total, 95% CI	Male, Mean±SD	Male, 95% CI	Female, Mean±SD	Female, 95% CI	P-value
Rest
EDV (mL)	70.8±17.6	36.3–105.3	79.6±18.2	43.9–115.3	63.4±13.3	37.3–89.5	<0.001
EDVI (mL/m2)	40.3±8.2	24.2–56.4	42.4±8.5	25.7–59.1	38.6±7.6	23.7–53.5	0.004
ESV (mL)	24.2±7.7	9.1–39.3	27.7±8.1	11.8–43.6	21.3±6.1	9.3–33.3	<0.001
ESVI (mL/m2)	13.7±3.8	6.3–21.1	14.7±3.9	7.1–22.3	12.9±3.5	6.0–19.8	0.003
SV (mL)	46.6±11.9	23.3–69.9	52.0±12.3	27.9–76.1	42.2±9.6	23.4–61.0	<0.001
SVI (mL/m2)	26.6±5.8	15.2–38.0	27.7±5.9	16.1–39.3	25.7±5.7	14.5–36.9	0.028
CO (L/min)	4.3±1.2	1.9–6.7	4.8±1.2	2.4–7.3	3.9±1.0	1.8–5.9	<0.001
CI (L/min/m2)	2.5±0.6	1.2–3.7	2.6±0.6	1.4–3.8	2.4±0.6	1.1–3.6	0.034
EF	0.66±0.06	0.54–0.78	0.65±0.06	0.53–0.77	0.66±0.06	0.54–0.78	0.320
Postexercise
EDV (mL)	61.9±16.9	28.8–95.0	64.2±18.7	27.5–100.9	60.1±15.0	30.7–89.5	0.133
EDVI (mL/m2)	35.5±8.8	18.3–52.7	34.2±9.0	16.6–51.8	36.5±8.5	19.8–53.2	0.094
ESV (mL)	11.8±5.5	1.0–22.6	11.4±5.8	0.03–22.8	12.1±5.3	1.7–22.5	0.455
ESVI (mL/m2)	6.8±3.1	0.7–12.9	6.1±2.9	0.4–11.8	7.4±3.1	1.3–13.5	0.009
SV (mL)	50.1±13.4	23.8–76.4	52.7±14.5	24.3–81.1	48.0±12.1	24.3–71.7	0.027
SVI (mL/m2)	28.7±7.0	15.0–42.2	28.1±7.0	14.4–41.8	29.2±6.9	15.7–42.7	0.336
CO (L/min)	8.2±2.3	3.7–13.3	8.8±2.5	3.9–13.7	7.8±2.1	3.7–11.9	0.006
CI (L/min/m2)	4.716±1.2	2.4–7.1	4.7±1.2	2.4–7.0	4.7±1.2	2.4–7.1	0.829
EF	0.81±0.05	0.71–0.91	0.83±0.05	0.73–0.93	0.80±0.05	0.70–0.90	0.004

Abbreviations: EDV, end diastolic volume; EDVI, end diastolic volume index; ESV, end systolic volume; ESVI, end systolic volume index; SV, stroke volume; SVI, stroke volume index; CO, cardiac output; CI, cardiac index; EF, ejection fraction.

Figure 2 LS changes during exercise at different levels of LV. The strain gradient at different levels of LV did not change either at rest or postexercise, with the highest LS at apex and the lowest LS at the base of LV. The LS of the apex increased much more than the other two levels.

Abbreviations: LS, longitudinal strain; LV, left ventricle.

Table 3 Changes in Exercise Characteristics

Parameters	Total, Mean±SD or Median (IQR)	Total, Limits of Normality ± SE†	Male, Mean±SD or Median (IQR)	Male, Limits of Normality ± SE†	Female, Mean±SD or Median (IQR)	Female, Limits of Normality ± SE†	P-value
ΔEF	0.15±0.06	0.05±0.01†	0.17±0.05	0.09±0.01†	0.14±0.05	0.06±0.01†	<0.001
ΔEFI (/m2)	0.09±0.03	0.04±0.003†	0.09±0.03	0.04±0.003†	0.09±0.04	0.03±0.004†	0.162
ΔEF to rest (%)	24.0±10.1	7.4±0.8†	27.0±9.8	10.9±1.2†	21.5±9.7	5.6±1.0†	0.001
ΔGLS (%)	5.0 (3.0–7.0)	1.0±0.25†	5.0 (3.0–7.0)	1.0±0.38†	4.0 (3.0–6.0)	0.5±0.31†	0.046
ΔGLSI (%/m2)	2.66±1.68	0.52±0.14†	2.77±1.65	0.52±0.19†	2.58±1.73	0.51±0.18†	0.485
ΔGLS to rest (%)	23.8 (12.8–35.1)	4.3±1.4†	27.0 (14.0–41.2)	4.8±2.2†	19.0 (12.2–30.2)	0.0±1.6†	0.007
ΔLSbase (%)	2.1 (1.0–3.7)	0.3±0.16†	1.9 (1.0–3.3)	0.2±0.27†	2.3 (0.9–4.0)	0.3±0.19†	0.509
ΔLSbase to rest (%)	11.5 (5.0–20.7)	1.5±1.1†	11.1 (5.3–21.1)	1.3±1.9†	11.7 (4.7–21.7)	1.5±1.1†	0.931
ΔLSmid (%)	3.4 (1.8–5.0)	0.5±0.32†	3.5 (1.9–4.9)	0.42±0.3†	3.3 (1.5–5.1)	0.5±0.53†	0.447
ΔLSmid to rest (%)	16.3 (8.3–27.1)	4.1±1.7†	18.4 (9.4–31.6)	5.9±1.7†	15.0 (7.5–25.5)	3.8±0.03†	0.093
ΔLSapex (%)	7.8 (4.6–11.6)	2.8±0.36†	9.1 (6.6–12.9)	2.8±0.57†	7.0 (4.4–10.0)	2.6±0.43†	0.012
ΔLSapex to rest (%)	31.5 (16.1–49.6)	7.1±2.0†	36.8 (18.2–61.5)	6.2±3.3†	28.2 (15.0–45.3)	7.0±2.3†	0.040

Note: †Lowest expected value.

Abbreviations: ΔEF, changes of ejection fraction; ΔEFI, changes of ejection fraction indexed by BSA; ΔGLS, changes of global longitudinal strain; ΔGLSI, changes of global longitudinal strain indexed by BSA; ΔLSbase, changes of longitudinal strain at the base of left ventricle; ΔLSmid, changes of longitudinal strain at the middle of left ventricle; ΔLSapex, changes of longitudinal strain at apex of left ventricle.

Figure 3 Correlation between parameters of LV contractile reserve and BSA. LV, left ventricle; BSA, body surface area; EF, ejection fraction; GLS, global longitudinal strain; %ΔEF, percentage of EF increase compared to rest; %ΔGLS, percentage of GLS increase compared to rest.