Assessment of Ventricular Repolarization in Sickle Cell Anemia Patients: The Role of QTc Interval, Tp-e Interval and Tp-e/QTc Ratio and Its Gender Implication

Figures & data

Figure 1 Measurement of the interval between the peak and the end of the T wave (Tp-e).

Table 1 Biological and Laboratory Parameters of the Study Population

Parameters	HbAA (60)	HbSS (60)	p-Value
Age (years)	25.9±5.5	25.2±6.7	1.000
Gender (M/F)	36/24	35/25
Weight (kg)	64.1±10.1	53.3±8.9	<0.001
Height (m)	1.69±0.1	1.65±0.1	0.006
Neck circumference (cm)	35.3±2.7	32.5±2.2	<0.001
Waist circumference (cm)	80.2±8.0	76.8±6.9	0.028
Hip circumference (cm)	94.4±7.7	89.4±7.4	0.001
Body mass index (kg/m^2)	22.4±2.9	19.6±2.7	<0.001
Red blood cells (×10^12/L)	4.8±0.7	3.2±0.7	<0.001
White blood cells (×10^9/L)	4.1±1.1	7.6±3.2	<0.001
Platelets (×10^9/L)	227.4±7.2	330.7±1.8	<0.001
Hemoglobin (g/dL)	130.4±12.5	85.9±14.2	<0.001
Hematocrit (%)	42.6±4.7	26.6±6.1	<0.001
Plasma viscosity	1.4±0.2	2.1±0.4	<0.001
Blood viscosity	3.4±0.5	4.0±1.0	0.015
Fasting glucose (mmol/L)	4.7±1.2	4.3±1.5	0.166
Triglyceride (mmol/L)	0.9±0.3	1.1±0.4	0.132
Total cholesterol (mmol/L)	5.3±1.0	4.6±1.5	0.003
HDL-cholesterol (mmol/L)	0.8±0.2	0.7±0.3	0.010
LDL-cholesterol (mmol/L)	4.1±1.0	3.2±1.5	<0.001
TG/HDL-cholesterol	1.2±0.4	1.2±0.5	1.000
TC/HDL-cholesterol	7.2±2.0	5.3±2.1	<0.001
C-reactive protein (mg/L)	3.2±0.5	5.9±0.7	0.035
PAI-1 (ng/mL)	13.5±2.7	92.8±5.2	<0.001

Notes: Means±SD. Significant difference (p˂0.05).

Abbreviations: AA, HbAA individuals (control); SS, HbSS individuals (sickle cell disease, SCD); TG, triglyceride; TC, total cholesterol; HDL-C, high-density lipoprotein cholesterol; LDL, low-density lipoprotein cholesterol; PAI-1, plasminogen activator inhibitor-1.

Table 2 Clinical and Electrocardiographic Variables of the Study Population

Parameters	HbAA (60)	HbSS (60)	p-Value
Systolic BP (mmHg)	112.4±10.4	106.1±14.4	0.015
Diastolic BP (mmHg)	75.0±9.5	61.1±10.6	<0.001
Pulse pressure (mmHg)	37.4±11.0	45.0±12.5	0.001
MAP (mmHg)	87.4±8.3	76.1±10.4	<0.001
Heart rate (bpm)	67.3±10.3	71.4±11.4	0.097
QT (ms)	366.4±23.5	387.5±23.7	<0.001
QTc (ms)	387.9±27.9	417.6±27.5	<0.001
Tp-e (ms)	80.0±16.2	82.7±15.4	1.000
Tp-e/QT ratio	0.22±0.1	0.21±0.1	1.000
Tp-e/QTc ratio	0.21±0.1	0.20±0.1	0.805

Notes: Means±SD. Significant difference (p˂0.05).

Abbreviations: AA, HbAA individuals (control); SS, HbSS individuals (SCD); BP, blood pressure; MAP, mean arterial pressure.

Table 3 Biological and Laboratory Parameters of the Study Population Characterized by Gender

Parameters	Male		Female
	HbAA (36)	HbSS (35)	HbAA (24)	HbSS (25)
Age (years)	27.8±6.3	26.5±7.8	23.0±1.7	24.5±6.0
Population	36	35	24	25
Weight (kg)	65.5±9.0	56.4±9.4*	62.1±11.4	51.5±8.2†
Height (m)	1.73±0.1	1.70±0.1	1.64±0.1	1.62±0.1
Neck circumference (cm)	36.3±2.7	34.5±0.9*	33.7±1.7	31.3±1.8†
Waist circumference (cm)	80.2±6.8	73.3±5.2*	80.3±9.6	78.9±6.9
Hip circumference (cm)	92.1±5.1	86.7±6.5*	97.7±9.7	91.0±7.5†
Body mass index (kg/m^2)	22.0±2.4	19.5±2.4*	23.0±3.5	19.7±2.8†
Red blood cells (×10^12/L)	5.0±0.7	3.2±0.5*	4.4±0.5	3.3±0.8†
White blood cells (×10^9/L)	3.9±0.9	7.9±2.7*	4.3±1.2	7.4±3.5†
Platelets (×10^9/L)	214.8±64.1	391.3±200.1*	246.3±81.0	298.8±159.2
Hemoglobin (g/dL)	131.9±11.9	83.8±12.1*	128.2±13.4	87.1±15.3†
Hematocrit (%)	43.4±4.8	26.0±4.5*	41.5±4.4	27.0±6.9†
Plasma viscosity	1.8±0.2	2.1±0.4*	1.8±0.2	2.0±0.3†
Blood viscosity	4.4±0.5	5.0±0.7*	4.4±0.4	5.0±1.1
Fasting glucose	4.8±1.5	4.3±1.5	4.6±0.5	4.5±1.5
Triglyceride (mmol/L)	0.8±0.2	0.9±0.4	1.0±0.3	1.1±0.4
Total cholesterol (mmol/L)	5.1±1.0	4.6±1.0*	5.5±1.1	4.6±1.7†
HDL-cholesterol (mmol/L)	0.8±0.2	0.7±0.2	0.7±0.1	0.6±0.3†
LDL-cholesterol (mmol/L)	4.0±1.0	3.3±0.9*	4.3±1.0	3.2±1.8†
TG/HDL-cholesterol	1.1±0.4	1.1±0.5	1.3±0.4	1.3±0.5
TC/HDL-cholesterol	7.0±2.3	5.6±1.6*	7.6±1.5	5.1±2.4†
C-reactive protein (mg/L)	3.5±0.6	6.1±0.7*	2.7±2.6	5.7±0.8†
PAI-1 (ng/mL)	16.4±35.4	79.3±27.8*	9.5±7.5	101.0±61.1†

Notes: Means±SD. Significant difference (p˂0.05). *Comparison of male AA to male SS. †Comparison of female AA to female SS.

Abbreviations: AA, HbAA individuals (control); SS, HbSS individuals (sickle cell disease, SCD); TG, triglyceride; TC, total cholesterol; HDL-C, high-density lipoprotein cholesterol; LDL, low-density lipoprotein cholesterol; PAI-1, plasminogen activator inhibitor-1.

Table 4 Clinical and Electrocardiographic Variables of the Study Population Characterized by Gender

Parameters	Male		Female
	HbAA (36)	HbSS (35)	HbAA (24)	HbSS (25)
Systolic BP (mmHg)	115.0±10.6	109.0±13.7	108.5±8.8	104.4±14.7
Diastolic BP (mmHg)	75.7±10.4	61.6±11.0*	73.9±8.1	60.8±10.5†
Pulse pressure (mmHg)	39.3±13.4	47.4±13.0*	34.6±5.1	43.6±12.2†
MAP (mmHg)	88.8±8.4	77.4±10.3*	85.4±8.0	75.4±10.6†
Heart rate (bpm)	65.1±8.6	70.9±6.5	70.6±11.9	75.8±11.3
QT (ms)	370.6±26.2	391.6±22.4*	360.0±17.5	385.0±24.4†
QTc (ms)	383.5±25.6	402.1±21.2*	394.5±30.7	426.9±26.8†
Tp-e (ms)	75.3±14.8	90.5±13.9*	87.3±15.8	78.1±14.5†
Tp-e/QT ratio	0.21±0.1	0.23±0.1*	0.24±0.1	0.20±0.1†
Tp-e/QTc ratio	0.20±0.1	0.22±0.1*	0.22±0.1	0.18±0.1†

Notes: Means±SD. Significant difference (p˂0.05). *Comparison of male AA to male SS. †Comparison of female AA to female SS.

Abbreviations: AA, HbAA individuals (control); SS, HbSS individuals (SCD); BP, blood pressure; MAP, mean arterial pressure.

Table 5 Linear Regression in the Sickle Cell Anemia Population (PAI-1 and QTc)

	Male QTc				Female QTc
	Beta	SE	β	p	Beta	SE	β	p
PAI-1	0.000	0.000	0.474	0.047	0.000	0.000	0.339	0.020

Notes: Male model r²=0.474; male model p=0.047; β, regression coefficient. Female model r²=0.594; female model p=0.003; β, regression coefficient. Significant difference (p˂0.05).

Abbreviation: PAI-1, plasminogen activator inhibitor-1.

Table 6 Linear Regression in the Sickle Cell Anemia Population (BMI and Tp-e)

	Male Tp-e				Female Tp-e
	Beta	SE	β	p	Beta	SE	β	p
BMI	0.006	0.001	0.926	<0.001	0.002	0.001	0.496	0.002

Notes: Male model r²=0.987; male model p<0.001; β, regression coefficient. Female model r²=0.665; female model p<0.001; β, regression coefficient. Significant difference (p˂0.05).

Abbreviation: BMI, body mass index.

Table 7 Linear Regression in the Sickle Cell Anemia Population (BMI and Tp-e/QTc Ratio)

	Male Tp-e/QTc Ratio				Female Tp-e/QTc Ratio
	Beta	SE	β	p	Beta	SE	β	p
BMI	0.014	0.003	0.833	0.006	0.006	0.002	0.550	0.002

Notes: Male model r²=0.866; male model p<0.001; β, regression coefficient. Female model r²=0.550; female model p=0.002; β, regression coefficient. Significant difference (p˂0.05).

Abbreviation: BMI, body mass index.