Association between Left-Handedness and Cardiac Autonomic Function in Healthy Young Men ¨ SINAN ˙IS ¸ CEN, M.D.,* SALIM OZENC ¸ , M.D.,† and URAT TAVLASOGLU, M.D.‡ From the *Department of Cardiology; †Department of Family Medicine; and ‡Department of Cardiovascular Surgery, Diyarbakir Military Hospital, Yenis¸ehir/Diyarbakir, Diyarbakir, Turkey
Background: Effects of nonright-handedness on risk for sudden death associated with coronary artery disease via sympathetic imbalance contributed to ventricular arrhythmogenesis previously have been demonstrated. This study hypothesized that left-handedness might be associated with cardiac autonomic functions in healthy young men. The aim of this study was to examine the association between lefthandedness and cardiac autonomic functions in healthy young men. Methods: A total of 992 asymptomatic young male subjects underwent routine health checkup between May 2012 and July 2013, and were included in this study. All were submitted to a standard protocol that included a complete clinical examination, laboratory evaluation, 12-lead electrocardiogram, and 2Dechocardiogram. Fifty-two subjects were left-handed; 32 subjects had abnormal QRS-T angle. Statistical analyses were performed using statistical package SPSS 15.0 (IBM Corp., Armonk, NY, USA) and statistical significance was assessed at the two-tailed 0.05 threshold. Results: A total of 52 (5%) subjects were left-handed; 32 (3%) subjects had an abnormal frontal QRST angle. The mean age, body mass index, systolic blood pressure, diastolic blood pressure, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, fasting glucose, current smoking, estimated glomerular filtration rate, hemoglobin, leukocyte count, platelet count, and echocardiographic parameters were not different between two groups. But subjects with left-handedness had greater prevalence of abnormal QRS-T angle. The left-handedness group had 18 subjects with abnormal QRS-T angle (34%) and the right-handedness group had 14 subjects with abnormal QRS-T angle (1.4%). The difference between two groups was significant (P < 0.001). Conclusion: In this study, there was a significant association between left-handedness and abnormal QRS-T angle in healthy young subjects. (PACE 2014; 37:884–888) left-handedness, abnormal QRS-T angle, cardiac autonomic function
Introduction Many studies have shown that lefthandedness is associated with several chronic diseases such as bronchial asthma,1 migraine,2 dyslexia,3 and diabetes mellitus.4 Effects of nonright-handedness on risk for sudden death associated with coronary artery disease via sympathetic imbalance contributed to ventricular arrhythmogenesis previously have been demonstrated. This study hypothesized that left-handedness might be associated with cardiac autonomic functions in healthy young men.5 The QRS-T angle is cardiac autonomic function parameter that has been showed to be increased in patients with type 2 diabetes who have cardiac autonomic neuropathy.6 The QRSAddress for reprints: Sinan Is¸cen, M.D., Diyarbakir Military Hospital, Mimar Sinan st., 21100 Yenisehir, Diyarbakir, Turkey. Fax: 09 004 122 236 237; e-mail: [email protected] Received October 26, 2013; revised January 2, 2014; accepted January 6, 2014. doi: 10.1111/pace.12365
T angle can be measured as their projections on the frontal plane, which is simpler and easily obtainable. It has also been demonstrated to predict cardiovascular morbidity and mortality in clinical7–9 and in general populations.10–14 The prognostic value of the QRS-T angle has never been evaluated in individuals with lefthandedness in healthy young men. The aim of this study was to examine the association between left-handedness and cardiac autonomic functions in healthy young men. Material and Methods Subjects A cross-sectional analysis was conducted among asymptomatic healthy young men. A total of 992 asymptomatic young male subjects underwent routine health checkup between May 2012 and July 2013. All were submitted to a standard protocol that includes a complete clinical examination, laboratory evaluation, 12-lead electrocardiogram (ECG), 2D-echocardiogram. Fifty-two subjects were left-handed, 32 subjects had abnormal QRS-T angle, and none of
©2014 Wiley Periodicals, Inc. 884
July 2014
PACE, Vol. 37
LEFT-HANDEDNESS AND CARDIAC AUTONOMIC FUNCTION
Figure 1. In the study, 52 (5%) subjects were left-handed; 32 (3%) subjects had an abnormal frontal QRS-T angle. There was significant difference in between two groups (P < 0.001). Left-handedness was associated with abnormal QRS-T angle.
them had a history of stroke; coronary heart disease; and antihypertensive, antidiabetic, or antihypercholesterolemic medications. Electrocardiography Standard resting 12-lead ECGs were recorded digitally with the same equipment (HP PageWriter 300Pi Interpretive EKG System, Agilent Technologies, Santa Clara, CA, USA) and response frequencies at 25 mm/s paper speed and 10 mm/mV amplitude. Frontal plane QRS and Twave axes were analyzed automatically with equipment (HP PageWriter 300Pi Interpretive EKG System). The frontal plane QRS-T angle was defined as the absolute value of the difference between QRS and T-wave axes; if frontal QRST angle was >180, its value was determined as follows: 360 – |QRS axis – T axis|.14 Frontal QRS-T angle was categorized as abnormal, if >73, for men based on the 95th percentile values of a populationbased study.14
PACE, Vol. 37
Laboratory Subjects’ heights and body weights were measured barefoot wearing light clothing. The body weight was measured with the subjects wearing light clothes provided by our center and the weight of the clothing was subtracted from the measured body weight. The body mass index (BMI) was calculated as the weight in kilograms divided by the square of the height in meters. Blood samples were obtained to measure the blood levels of routinely evaluated laboratory values: plasma glucose, triglycerides, high-density lipoprotein (HDL) cholesterol, lowdensity lipoprotein (LDL) cholesterol, hemoglobin (Hgb), blood cell counts, and kidney function tests after an overnight fasting. The simple qualitative urinalyses were performed with test papers. The chemical measurements were all performed at DMH (Diyarbakır Military Hospital, Turkey) using routine laboratory methods. The estimated glomerular filtration rate (eGFR) was calculated as
July 2014
885
˙IS ¸ CEN ET AL.
Table I. Laboratory Data between Subjects with and Without Left-Handedness
n Male sex (%) Age (years) Current smoking (%) SBP (mm Hg) DBP (mm Hg) LDL (mg/dL) HDL (mg/dL) Triglycerides (mg/dL) Fasting glucose (mg/dL) Leucocyte count (/mL) Hemoglobin (g/dL) Platelet count (/mL) eGFR (mL/min/1.73 m2 ) BMI (kg/m2 ) Abnormal QRS-T angle
With LeftHandedness 52 (5%)
With RightHandedness 940 (95%)
100 33.1 ± 2.2 16.1 120 ± 11 70 ± 14 121 ± 28 59.1 ± 19 110 ± 25 100 ± 15 5,480 ± 1,635 14.2 ± 1.4 246,000 ± 22,000 88.0 ± 12.7(MDRD) 25.6 ± 4.7 18
100 31.4 ± 2.1 15.2 122 ± 18 72 ± 14 121 ± 21 59.0 ± 11 110 ± 52 99 ± 16 5,480 ± 998 14.6 ± 1.2 242,000 ± 35,000 85 ± 13.3(MDRD) 25.5 ± 4.1 14
P = 0.07 P = 0.11 P = 0.16 P = 0.10 P = 0.17 P = 0.13 P = 0.32 P = 0.21 P = 0.16 P = 0.12 P = 0.11 P = 0.89 P = 0.079 P < 0.001
BMI = body mass index; DBP = diastolic blood pressure; eGFR = estimated glomerular filtration rate; HDL = high-density lipoprotein; LDL = low-density lipoprotein; MDRD = Modification of Diet in Renal Disease; SBP = systolic blood pressure.
Table II. Echocardiographic Data between Subjects with and Without Left-Handedness
n End-diastolic LV diameter (cm) End-systolic LV diameter (cm) LV ejection fraction (%) LA diameter (cm)
With LeftHandedness 52 (5%)
With RightHandedness 940 (95%)
P
5.2 + 0.7
5.2 + 0.2
0.17
2.9 + 0.4
2.9 + 0.5
0.18
73.4 + 6.2
73.4 + 7.7
0.12
3.25 + 0.2
3.36 + 0.1
0.13
LA = left atrial; LV = left ventricular.
the eGFR (Modification of Diet in Renal Disease, mL/min/1.73 m2 ). An average systolic blood pressure (SBP) and diastolic blood pressure (DBP) was calculated from two measurements with the subjects in a sitting position after a 5-minute rest period. Echocardiograhy All patients were evaluated with standard 2D echocardiography. All echocardiographic measurements were performed using a commercially
886
available ultrasound system (Philips echocardiography machine version hd7xe, Koninklijke Philips N.V., Eindhoven, The Netherlands) equipped with a harmonic 4.0–2.5-MHz variable—frequency phased-array transducer. Images were taken in left decubitus position. M-mode echocardiography was performed to evaluate left ventricular enddiastolic diameter, interventricular septum thickness, and left atrium diameter. Left ventricular ejection fraction was assessed using Simpson’s rule. Transthoracic 2D echocardiography (2DTTE) was performed in all study subjects according to the published protocol adopted form the recommendations of the American Society of Echocardiography. Statistical analysis Data were expressed as means ± standard deviation, medians, or percentages. Subjects were categorized according to left-handedness and right-handedness. Results were expressed as subject number with percentage (%) and mean value with standard deviation. The unpaired t-test (for continuous variables) and the χ 2 test or the Fisher’s exact test when appropriate (for categorical variables) were used to analyze the differences among the characteristics of the participants at the time of enrollment in the study. All analyses were performed using statistical package SPSS 15.0 (IBM Corp., Armonk, NY, USA) and statistical
July 2014
PACE, Vol. 37
LEFT-HANDEDNESS AND CARDIAC AUTONOMIC FUNCTION
significance was assessed at the two-tailed 0.05 threshold. Results Fifty-two (5%) subjects were left-handed; 32 (3%) subjects had an abnormal frontal QRS-T angle (Fig. 1). Table I outlines the characteristics of subjects with left-handedness and righthandedness. The mean age, BMI, SBP, DBP, HDL cholesterol, LDL cholesterol, triglycerides, fasting glucose, current smoking, eGFR, Hgb, leukocyte count, platelet count, and echocardiographic parameters (Table II) were not different between two groups. But subjects with left-handedness had greater prevalence of abnormal QRS-T angle. The left-handedness group had 18 subjects with abnormal QRS-T angle (34%); the right-handedness group had 14 subjects with abnormal QRS-T angle (1.4%). The difference between the two groups was significant (P < 0.001). Discussion In this study, left-handedness was independently associated with abnormal QRS-T angle. Handedness is determined during fetal development.15 Most individuals with righthandedness show left-hemisphere dominance, while some left-handed individuals show righthemisphere dominance. Many studies have shown that left-handedness is associated with several chronic diseases such as bronchial asthma,1 migraine,2 dyslexia,3 and diabetes mellitus.4 It has previously been demonstrated that effects of nonright-handedness on risk for sudden death associated with coronary artery disease via sympathetic imbalance contributed to ventricular arrhythmogenesis.5 Although the previous study demonstrated the relation between dominant handedness and some anthropometric variables, including BMI and smoking,16 we could not find any differences of such factors between lefthanded and right-handed individuals. The frontal QRS-T angle is an easily obtainable electrocardiographic parameter, defined as the angle between the frontal QRS and Twave electrical axes, both of which are routinely calculated using standard electrocardiographic diagnostic software. This angle is an approximation of the spatial QRS-T angle, the angle between
the spatial axes of ventricular depolarization and repolarization. A greater angle represents a larger discordance between depolarization and repolarization. This signifies abnormal and heterogeneous ventricular repolarization. The QRS-T angle is cardiac autonomic function parameter that has been shown to be increased in patients with type 2 diabetes who have cardiac autonomic neuropathy.6 It has been demonstrated to predict cardiovascular morbidity and mortality in clinical7–9 and in general populations.10–14 To the best of our knowledge, there has been no study showing an independent association between left-handedness and abnormal QRS-T angle in healthy young men. The mean age, BMI, SBP, DBP, HDL cholesterol, LDL cholesterol, triglycerides, fasting glucose, current smoking, eGFR, Hgb, leukocyte count, platelet count, and echocardiographic parameters (Table II) were not different between two groups. But left-handedness was associated with an increased risk of abnormal QRS-T angle. Limitations This study has some limitations. First, we did not obtain the spatial T-wave axis and QRST angle, which needs computerized algorithms of vectorcardiographic reconstruction, but their readily obtainable frontal plane projections, which are expected to be dependent on variations of the anatomic position of the heart into the thorax. Second, as discussed previously, its crosssectional design did not allow any cause-andeffect inference. Finally, this study was carried on in a secondary-care hospital and included young men individuals. Hence, our results may not be generalized to all ages and all sex. Conclusion We found a significant association between left-handedness and abnormal QRS-T angle in the healthy young subjects. Because most individuals with right-handedness show left-hemisphere dominance, while some left-handed individuals show right-hemisphere dominance, the present results suggest that cerebral lateralization might affect the QRS-T as a cardiac autonomic function parameter.
References 1. Krommydas G, Gourgoulianis KI, Andreou G, Molyvdas PA. Lefthandedness in asthmatic children. Pediatr Allergy Immunol 2003; 14:234–237. 2. Waldie KE, Hausmann M, Milne BJ, Poulton R. Migraine and cognitive function: A lifecourse study. Neurology 2002; 59:904– 908.
PACE, Vol. 37
3. Tønnessen FE, Løkken A, Høien T, Lundberg I. Dyslexia, lefthandedness, and immune disorders. Arch Neurol 1993; 50:411–416. 4. Searleman A, Fugagli AK. Suspected autoimmune disorders and left-handedness: Evidence from individuals with diabetes. Crohn’s disease and ulcerative colitis. Neuropsychologia 1987; 25:367– 374.
July 2014
887
˙IS ¸ CEN ET AL. 5. Effects of non-right-handedness on risk for sudden death associated with coronary artery disease. Am J Cardiol 1994; 74:743–747. 6. Voulgari C, Moyssakis I, Perrea D, Kyriaki D, Katsilambros N, Tentolouris N. The association between the spatial QRS-T angle with cardiac autonomic neuropathy in subjects with Type 2 diabetes mellitus. Diabet Med 2010; 27:1420–1429. 7. Alagiakrishnan K, Beitel JD, Graham MM, Southern D, Knudtson M, Ghali WA, Tsuyuki RT; APPROACH Investigators. Relation of T-axis abnormalities to coronary artery disease and survival after cardiac catheterization. Am J Cardiol 2005; 96:639–642. 8. Borleffs CJ, Scherptong RW, Man SC, van Welsenes GH, Bax JJ, van Erven L, Swenne CA, et al. Predicting ventricular arrhythmias in patients with ischemic heart disease: Clinical application of the ECG-derived QRS-T angle. Circ Arrhythm Electrophysiol 2009; 2:548–554. 9. Yamazaki T, Froelicher VF, Myers J, Chun S, Wang P. Spatial QRS-T angle predicts cardiac death in a clinical population. Heart Rhythm 2005; 2:73–78. 10. Aro AL, Huikuri HV, Tikkanen JT, Junttila MJ, Rissanen HA, Reunanen A, Anttonen O., et al. QRS-T angle as a predictor of sudden cardiac death in a middle-aged general population. Europace 2012; 14:872–876.
888
11. Kors JA, de Bruyne MC, Hoes AW, van Herpen G, Hofman A, van Bemmel JH, Grobbee DE. T axis as an indicator of risk of cardiac events in elderly people. Lancet 1998; 352:601–605. 12. Rautaharju PM, Nelson JC, Kronmal RA, Zhang ZM, Robbins J, Gottdiener JS, Furberg CD, et al. Usefulness of T-axis deviation as an independent risk indicator for incident cardiac events in older men and women free from coronary heart disease (the Cardiovascular Health Study). Am J Cardiol 2001; 88:118–123. 13. Kardys I, Kors JA, van der Meer IM, Hofman A, van der Kuip DA, Witteman JC. Spatial QRS-T angle predicts cardiac death in a general population. Eur Heart J 2003; 24:1357–1364. 14. Zhang ZM, Prineas RJ, Case D, Soliman EZ, Rautaharju PM, ARIC Research Group. Comparison of the prognostic significance of the electrocardiographic QRS/T angles in predicting incident coronary heart disease and total mortality (from the Atherosclerosis Risk in Communities Study). Am J Cardiol 2007; 100:844– 849. 15. Hepper PG, Shahidullah S, White R. Handedness in the human fetus. Neuropsychologia 1991; 29:1107–1111. 16. Koley S, Singh AP. An association of dominant hand grip strength with some anthropometric variables in Indian collegiate population. Anthropol Anz 2009; 67:21–28.
July 2014
PACE, Vol. 37
Background: Effects of nonright-handedness on risk for sudden death associated with coronary artery disease via sympathetic imbalance contributed to ventricular arrhythmogenesis previously have been demonstrated. This study hypothesized that left-handedness might be associated with cardiac autonomic functions in healthy young men. The aim of this study was to examine the association between lefthandedness and cardiac autonomic functions in healthy young men. Methods: A total of 992 asymptomatic young male subjects underwent routine health checkup between May 2012 and July 2013, and were included in this study. All were submitted to a standard protocol that included a complete clinical examination, laboratory evaluation, 12-lead electrocardiogram, and 2Dechocardiogram. Fifty-two subjects were left-handed; 32 subjects had abnormal QRS-T angle. Statistical analyses were performed using statistical package SPSS 15.0 (IBM Corp., Armonk, NY, USA) and statistical significance was assessed at the two-tailed 0.05 threshold. Results: A total of 52 (5%) subjects were left-handed; 32 (3%) subjects had an abnormal frontal QRST angle. The mean age, body mass index, systolic blood pressure, diastolic blood pressure, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, fasting glucose, current smoking, estimated glomerular filtration rate, hemoglobin, leukocyte count, platelet count, and echocardiographic parameters were not different between two groups. But subjects with left-handedness had greater prevalence of abnormal QRS-T angle. The left-handedness group had 18 subjects with abnormal QRS-T angle (34%) and the right-handedness group had 14 subjects with abnormal QRS-T angle (1.4%). The difference between two groups was significant (P < 0.001). Conclusion: In this study, there was a significant association between left-handedness and abnormal QRS-T angle in healthy young subjects. (PACE 2014; 37:884–888) left-handedness, abnormal QRS-T angle, cardiac autonomic function
Introduction Many studies have shown that lefthandedness is associated with several chronic diseases such as bronchial asthma,1 migraine,2 dyslexia,3 and diabetes mellitus.4 Effects of nonright-handedness on risk for sudden death associated with coronary artery disease via sympathetic imbalance contributed to ventricular arrhythmogenesis previously have been demonstrated. This study hypothesized that left-handedness might be associated with cardiac autonomic functions in healthy young men.5 The QRS-T angle is cardiac autonomic function parameter that has been showed to be increased in patients with type 2 diabetes who have cardiac autonomic neuropathy.6 The QRSAddress for reprints: Sinan Is¸cen, M.D., Diyarbakir Military Hospital, Mimar Sinan st., 21100 Yenisehir, Diyarbakir, Turkey. Fax: 09 004 122 236 237; e-mail: [email protected] Received October 26, 2013; revised January 2, 2014; accepted January 6, 2014. doi: 10.1111/pace.12365
T angle can be measured as their projections on the frontal plane, which is simpler and easily obtainable. It has also been demonstrated to predict cardiovascular morbidity and mortality in clinical7–9 and in general populations.10–14 The prognostic value of the QRS-T angle has never been evaluated in individuals with lefthandedness in healthy young men. The aim of this study was to examine the association between left-handedness and cardiac autonomic functions in healthy young men. Material and Methods Subjects A cross-sectional analysis was conducted among asymptomatic healthy young men. A total of 992 asymptomatic young male subjects underwent routine health checkup between May 2012 and July 2013. All were submitted to a standard protocol that includes a complete clinical examination, laboratory evaluation, 12-lead electrocardiogram (ECG), 2D-echocardiogram. Fifty-two subjects were left-handed, 32 subjects had abnormal QRS-T angle, and none of
©2014 Wiley Periodicals, Inc. 884
July 2014
PACE, Vol. 37
LEFT-HANDEDNESS AND CARDIAC AUTONOMIC FUNCTION
Figure 1. In the study, 52 (5%) subjects were left-handed; 32 (3%) subjects had an abnormal frontal QRS-T angle. There was significant difference in between two groups (P < 0.001). Left-handedness was associated with abnormal QRS-T angle.
them had a history of stroke; coronary heart disease; and antihypertensive, antidiabetic, or antihypercholesterolemic medications. Electrocardiography Standard resting 12-lead ECGs were recorded digitally with the same equipment (HP PageWriter 300Pi Interpretive EKG System, Agilent Technologies, Santa Clara, CA, USA) and response frequencies at 25 mm/s paper speed and 10 mm/mV amplitude. Frontal plane QRS and Twave axes were analyzed automatically with equipment (HP PageWriter 300Pi Interpretive EKG System). The frontal plane QRS-T angle was defined as the absolute value of the difference between QRS and T-wave axes; if frontal QRST angle was >180, its value was determined as follows: 360 – |QRS axis – T axis|.14 Frontal QRS-T angle was categorized as abnormal, if >73, for men based on the 95th percentile values of a populationbased study.14
PACE, Vol. 37
Laboratory Subjects’ heights and body weights were measured barefoot wearing light clothing. The body weight was measured with the subjects wearing light clothes provided by our center and the weight of the clothing was subtracted from the measured body weight. The body mass index (BMI) was calculated as the weight in kilograms divided by the square of the height in meters. Blood samples were obtained to measure the blood levels of routinely evaluated laboratory values: plasma glucose, triglycerides, high-density lipoprotein (HDL) cholesterol, lowdensity lipoprotein (LDL) cholesterol, hemoglobin (Hgb), blood cell counts, and kidney function tests after an overnight fasting. The simple qualitative urinalyses were performed with test papers. The chemical measurements were all performed at DMH (Diyarbakır Military Hospital, Turkey) using routine laboratory methods. The estimated glomerular filtration rate (eGFR) was calculated as
July 2014
885
˙IS ¸ CEN ET AL.
Table I. Laboratory Data between Subjects with and Without Left-Handedness
n Male sex (%) Age (years) Current smoking (%) SBP (mm Hg) DBP (mm Hg) LDL (mg/dL) HDL (mg/dL) Triglycerides (mg/dL) Fasting glucose (mg/dL) Leucocyte count (/mL) Hemoglobin (g/dL) Platelet count (/mL) eGFR (mL/min/1.73 m2 ) BMI (kg/m2 ) Abnormal QRS-T angle
With LeftHandedness 52 (5%)
With RightHandedness 940 (95%)
100 33.1 ± 2.2 16.1 120 ± 11 70 ± 14 121 ± 28 59.1 ± 19 110 ± 25 100 ± 15 5,480 ± 1,635 14.2 ± 1.4 246,000 ± 22,000 88.0 ± 12.7(MDRD) 25.6 ± 4.7 18
100 31.4 ± 2.1 15.2 122 ± 18 72 ± 14 121 ± 21 59.0 ± 11 110 ± 52 99 ± 16 5,480 ± 998 14.6 ± 1.2 242,000 ± 35,000 85 ± 13.3(MDRD) 25.5 ± 4.1 14
P = 0.07 P = 0.11 P = 0.16 P = 0.10 P = 0.17 P = 0.13 P = 0.32 P = 0.21 P = 0.16 P = 0.12 P = 0.11 P = 0.89 P = 0.079 P < 0.001
BMI = body mass index; DBP = diastolic blood pressure; eGFR = estimated glomerular filtration rate; HDL = high-density lipoprotein; LDL = low-density lipoprotein; MDRD = Modification of Diet in Renal Disease; SBP = systolic blood pressure.
Table II. Echocardiographic Data between Subjects with and Without Left-Handedness
n End-diastolic LV diameter (cm) End-systolic LV diameter (cm) LV ejection fraction (%) LA diameter (cm)
With LeftHandedness 52 (5%)
With RightHandedness 940 (95%)
P
5.2 + 0.7
5.2 + 0.2
0.17
2.9 + 0.4
2.9 + 0.5
0.18
73.4 + 6.2
73.4 + 7.7
0.12
3.25 + 0.2
3.36 + 0.1
0.13
LA = left atrial; LV = left ventricular.
the eGFR (Modification of Diet in Renal Disease, mL/min/1.73 m2 ). An average systolic blood pressure (SBP) and diastolic blood pressure (DBP) was calculated from two measurements with the subjects in a sitting position after a 5-minute rest period. Echocardiograhy All patients were evaluated with standard 2D echocardiography. All echocardiographic measurements were performed using a commercially
886
available ultrasound system (Philips echocardiography machine version hd7xe, Koninklijke Philips N.V., Eindhoven, The Netherlands) equipped with a harmonic 4.0–2.5-MHz variable—frequency phased-array transducer. Images were taken in left decubitus position. M-mode echocardiography was performed to evaluate left ventricular enddiastolic diameter, interventricular septum thickness, and left atrium diameter. Left ventricular ejection fraction was assessed using Simpson’s rule. Transthoracic 2D echocardiography (2DTTE) was performed in all study subjects according to the published protocol adopted form the recommendations of the American Society of Echocardiography. Statistical analysis Data were expressed as means ± standard deviation, medians, or percentages. Subjects were categorized according to left-handedness and right-handedness. Results were expressed as subject number with percentage (%) and mean value with standard deviation. The unpaired t-test (for continuous variables) and the χ 2 test or the Fisher’s exact test when appropriate (for categorical variables) were used to analyze the differences among the characteristics of the participants at the time of enrollment in the study. All analyses were performed using statistical package SPSS 15.0 (IBM Corp., Armonk, NY, USA) and statistical
July 2014
PACE, Vol. 37
LEFT-HANDEDNESS AND CARDIAC AUTONOMIC FUNCTION
significance was assessed at the two-tailed 0.05 threshold. Results Fifty-two (5%) subjects were left-handed; 32 (3%) subjects had an abnormal frontal QRS-T angle (Fig. 1). Table I outlines the characteristics of subjects with left-handedness and righthandedness. The mean age, BMI, SBP, DBP, HDL cholesterol, LDL cholesterol, triglycerides, fasting glucose, current smoking, eGFR, Hgb, leukocyte count, platelet count, and echocardiographic parameters (Table II) were not different between two groups. But subjects with left-handedness had greater prevalence of abnormal QRS-T angle. The left-handedness group had 18 subjects with abnormal QRS-T angle (34%); the right-handedness group had 14 subjects with abnormal QRS-T angle (1.4%). The difference between the two groups was significant (P < 0.001). Discussion In this study, left-handedness was independently associated with abnormal QRS-T angle. Handedness is determined during fetal development.15 Most individuals with righthandedness show left-hemisphere dominance, while some left-handed individuals show righthemisphere dominance. Many studies have shown that left-handedness is associated with several chronic diseases such as bronchial asthma,1 migraine,2 dyslexia,3 and diabetes mellitus.4 It has previously been demonstrated that effects of nonright-handedness on risk for sudden death associated with coronary artery disease via sympathetic imbalance contributed to ventricular arrhythmogenesis.5 Although the previous study demonstrated the relation between dominant handedness and some anthropometric variables, including BMI and smoking,16 we could not find any differences of such factors between lefthanded and right-handed individuals. The frontal QRS-T angle is an easily obtainable electrocardiographic parameter, defined as the angle between the frontal QRS and Twave electrical axes, both of which are routinely calculated using standard electrocardiographic diagnostic software. This angle is an approximation of the spatial QRS-T angle, the angle between
the spatial axes of ventricular depolarization and repolarization. A greater angle represents a larger discordance between depolarization and repolarization. This signifies abnormal and heterogeneous ventricular repolarization. The QRS-T angle is cardiac autonomic function parameter that has been shown to be increased in patients with type 2 diabetes who have cardiac autonomic neuropathy.6 It has been demonstrated to predict cardiovascular morbidity and mortality in clinical7–9 and in general populations.10–14 To the best of our knowledge, there has been no study showing an independent association between left-handedness and abnormal QRS-T angle in healthy young men. The mean age, BMI, SBP, DBP, HDL cholesterol, LDL cholesterol, triglycerides, fasting glucose, current smoking, eGFR, Hgb, leukocyte count, platelet count, and echocardiographic parameters (Table II) were not different between two groups. But left-handedness was associated with an increased risk of abnormal QRS-T angle. Limitations This study has some limitations. First, we did not obtain the spatial T-wave axis and QRST angle, which needs computerized algorithms of vectorcardiographic reconstruction, but their readily obtainable frontal plane projections, which are expected to be dependent on variations of the anatomic position of the heart into the thorax. Second, as discussed previously, its crosssectional design did not allow any cause-andeffect inference. Finally, this study was carried on in a secondary-care hospital and included young men individuals. Hence, our results may not be generalized to all ages and all sex. Conclusion We found a significant association between left-handedness and abnormal QRS-T angle in the healthy young subjects. Because most individuals with right-handedness show left-hemisphere dominance, while some left-handed individuals show right-hemisphere dominance, the present results suggest that cerebral lateralization might affect the QRS-T as a cardiac autonomic function parameter.
References 1. Krommydas G, Gourgoulianis KI, Andreou G, Molyvdas PA. Lefthandedness in asthmatic children. Pediatr Allergy Immunol 2003; 14:234–237. 2. Waldie KE, Hausmann M, Milne BJ, Poulton R. Migraine and cognitive function: A lifecourse study. Neurology 2002; 59:904– 908.
PACE, Vol. 37
3. Tønnessen FE, Løkken A, Høien T, Lundberg I. Dyslexia, lefthandedness, and immune disorders. Arch Neurol 1993; 50:411–416. 4. Searleman A, Fugagli AK. Suspected autoimmune disorders and left-handedness: Evidence from individuals with diabetes. Crohn’s disease and ulcerative colitis. Neuropsychologia 1987; 25:367– 374.
July 2014
887
˙IS ¸ CEN ET AL. 5. Effects of non-right-handedness on risk for sudden death associated with coronary artery disease. Am J Cardiol 1994; 74:743–747. 6. Voulgari C, Moyssakis I, Perrea D, Kyriaki D, Katsilambros N, Tentolouris N. The association between the spatial QRS-T angle with cardiac autonomic neuropathy in subjects with Type 2 diabetes mellitus. Diabet Med 2010; 27:1420–1429. 7. Alagiakrishnan K, Beitel JD, Graham MM, Southern D, Knudtson M, Ghali WA, Tsuyuki RT; APPROACH Investigators. Relation of T-axis abnormalities to coronary artery disease and survival after cardiac catheterization. Am J Cardiol 2005; 96:639–642. 8. Borleffs CJ, Scherptong RW, Man SC, van Welsenes GH, Bax JJ, van Erven L, Swenne CA, et al. Predicting ventricular arrhythmias in patients with ischemic heart disease: Clinical application of the ECG-derived QRS-T angle. Circ Arrhythm Electrophysiol 2009; 2:548–554. 9. Yamazaki T, Froelicher VF, Myers J, Chun S, Wang P. Spatial QRS-T angle predicts cardiac death in a clinical population. Heart Rhythm 2005; 2:73–78. 10. Aro AL, Huikuri HV, Tikkanen JT, Junttila MJ, Rissanen HA, Reunanen A, Anttonen O., et al. QRS-T angle as a predictor of sudden cardiac death in a middle-aged general population. Europace 2012; 14:872–876.
888
11. Kors JA, de Bruyne MC, Hoes AW, van Herpen G, Hofman A, van Bemmel JH, Grobbee DE. T axis as an indicator of risk of cardiac events in elderly people. Lancet 1998; 352:601–605. 12. Rautaharju PM, Nelson JC, Kronmal RA, Zhang ZM, Robbins J, Gottdiener JS, Furberg CD, et al. Usefulness of T-axis deviation as an independent risk indicator for incident cardiac events in older men and women free from coronary heart disease (the Cardiovascular Health Study). Am J Cardiol 2001; 88:118–123. 13. Kardys I, Kors JA, van der Meer IM, Hofman A, van der Kuip DA, Witteman JC. Spatial QRS-T angle predicts cardiac death in a general population. Eur Heart J 2003; 24:1357–1364. 14. Zhang ZM, Prineas RJ, Case D, Soliman EZ, Rautaharju PM, ARIC Research Group. Comparison of the prognostic significance of the electrocardiographic QRS/T angles in predicting incident coronary heart disease and total mortality (from the Atherosclerosis Risk in Communities Study). Am J Cardiol 2007; 100:844– 849. 15. Hepper PG, Shahidullah S, White R. Handedness in the human fetus. Neuropsychologia 1991; 29:1107–1111. 16. Koley S, Singh AP. An association of dominant hand grip strength with some anthropometric variables in Indian collegiate population. Anthropol Anz 2009; 67:21–28.
July 2014
PACE, Vol. 37
