Serum Zinc Level in Dilated and Ischemic Cardiomyopathy
Seyed Mahmood Nouraei, MD1*, Ali Ghayemian, MD1, Ebrahim Salehifar, PhD2
1Mazandaran Heart Centre, Mazandaran University of Medical Sciences, Sari, Iran.
2Department of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran.
Receive 18 December 2006; Accepted 5 March 2007
Background: Serum trace element alteration has been reported in dilated and ischemic cardiomyopathy. The reports were controversial. We have studied serum Zinc level in cardiomyopathy patients in northern province of Mazandaran and compared them with healthy volunteers.
Methods: Serum Zinc level was measured in 30 ischemic and 18 dilated cardiomyopathy patients against 27 healthy volunteers. It was measured using atomic absorption spectrophotometry. Statistical analysis was performed using SPSS for Windows version 14 and independent t-test was used for comparing serum Zinc level in ischemic and dilated cardiomyopathy. Pearson correlation and ANOVA tests were used for numeric variables in three different groups. P<0.05 was considered as statistically significant.
Results: The mean serum Zinc level was 0.97±0.25, 1.05±0.27, 1.21±0.42 mg/L for idiopathic dilated cardiomyopathy, ischemic cardiomyopathy and healthy volunteers respectively. There was no significant difference between three groups. There was also no correlation between echocardiography data and serum Zinc level.
Conclusion: This study showed serum Zinc level might not have a role in pathogenesis of ischemic and dilated cardiomyopathy. As intracellular Zinc level play a role in heart subjected to ischemia- reperfusion, measuring intracellular Zinc may give us a better clue about role of Zinc or other trace elements in pathogenesis of cardiomyopathy.
J Teh Univ Heart Ctr 3 (2007) 157-160
Ischemic cardiomyopathy • Dilated cardiomyopathy • Zinc
*Corresponding Author: Seyed Mahmood Nouraei, Assistance Professor of Cardiac Surgery, Mazandaran Heart Center, Mazandaran University of Medical Sciences, Serahe Joybar, Sari, Iran. 48157-33971. Tel: +98 09111542175. Fax: +98 01512224002. Email: email@example.com.
Congestive heart failure (CHF) is a debilitating condition affecting 1.5-2% of general population and is due to failure of the heart to pump blood into the circulatory system.1 Prognosis of CHF is poor and classical symptoms are edema, fatigue, tiredness and shortness of breath affecting patient’s quality of life and their life expectancy. 30-50% of CHF patients will die during the first year of diagnosis and 70% do not survive up to three years.2-3
Cardiomyopathy is a group of diseases affecting heart muscle. In this group, high blood pressure, congenital heart disease and valvular or pericardial disease do not have any role in their etiology. The most common form is dilated cardiomyopathy, which presents as a mono or biventricular failure. Ischemic cardiomyopathy (ISCMP) is due to coronary artery disease and insufficient myocardial blood supply. In idiopathic dilated cardiomyopathy (IDCMP) we can not establish a causative etiology for cardiomyopathy.3
The most principle cause of cardiomyopathy is high afterload, and preload and low myocardial contractility, however, imbalance of trace elements may cause myocardial metabolic dysfunction and may play a role in etiology of cardiomyopathy especially in IDCMP.4
The role of Zinc in pathogenesis of idiopathic dilated cardiomyopathy is unclear. Some researchers showed lower serum Zinc levels present in patients when compared with the control group4-8 and others showed no relation between serum Zinc level and IDCMP.7-9
In ischemic cardiomyopathy, both high serum Zinc level10 and low serum Zinc level8 have been reported.
As there is controversy regarding role of Zinc in pathogenesis of cardiomyopathy, we investigated its serum level in ischemic and dilated cardiomyopathy patients and compared them with a control group.
A correlational study was performed on 75 patients in three different groups in Mazandaran Heart Centre in Sari, Iran. Group one included 18 patients with Idiopathic Dilated Cardiomyopathy, group two 30
patients with ischemic cardiomyopathy and group three 27 healthy individuals.
Inclusion criterions for patient group were individuals with clinical symptoms and signs of heart failure i.e. shortness of breath, edema and low exercise tolerance. Clinical history, physical examination, 12 lead ECG, Chest X-ray and Echocardiography were diagnostic tools for CHF.
In idiopathic dilated cardiomyopathy, a normal coronary angiography and echocardiography with no valvular or pericardial disease and no history of myocarditis
were mandatory. Ischemic cardiomyopathy was diagnosed by history of myocardial infarction and an abnormal coronary angiography.
In healthy individuals, clinical history, physical examination and routine laboratory blood tests including: FBS, BUN, Creatinine, LFT, TG, and serum cholesterol and echocardiography were performed to rule out any underlying heart condition.
Exclusion criteria in patient group were renal and or liver disease, alcohol consumption plus vitamin supplement intakes such as multivitamin mineral, multivitamin therapeutic, or Zinc Sulfate within the past week. An exclusion criterion for control group was any disease or any medication for the past week.
Every individual person within the patient and control group had given informed consent for the study and clinical and para-clinical information was documented in study datasheet.
15cc of venous blood was taken from patients and the control group; it was transferred into a plastic test tube and was incubated for an hour in 37oC incubator. Serum was then separated from blood cells using a centrifuge and was kept at –20oc freezer.
For Zinc measurement we made a standard Zinc solution of 0.1%, 0.2%, 0.3% and 0.4% and then defreezed the serum. One cc of defreezed serum sample was put into a Balloon Jujeh and 5% Glycerol solution was added into it. The standard solutions and the serum sample solution Zinc level was then measured using Flame Atomic Absorption Spectrometry (Perking Elmer Analyst 100). Using 213.9 nanometer wavelength, the standard solution curves and equation line Serum Zinc level drawings were calculated.
For statistical analysis, we used SPSS 14 software for windows (SPSS Inc. Chicago Ill. USA), to measure mean Zinc level in different samples taken from a single group. We used independent t-test and to compare mean Zinc level in three different groups of samples we used (ANOVA) or analysis of variant test. Pearson correlation was used for quantitative data correlation. A p value of <0.05 was considered statistically significant.
Patient and control group demographic data are shown in table 1. Forty percent of ischemic cardiomyopathy group and 47% of dilated cardiomyopathy group were female. Mean age was higher in ISCMP compared to IDCMP and control group. Fasting blood sugar was within normal range in patient groups and mean BUN, creatinine, liver function tests, TG, and cholesterol levels were within normal limits in all groups.
Table 2 shows mean Zinc level and echocardiography data in three groups. There was no statistically significant difference between Zinc level in patient group and healthy individuals with a p value of 0.42 between control and ISCMP group and a p value of 0.18 between control and IDCMP group. There was a significant difference between LVESD and LVEDD of normal volunteers and patients in ISCMP and IDCMP group with a p value of less than 0.001.
Echocardiography data of ISCMP and control group shows a mean difference of 8.52 (6.01-11.03) of
LVESD with a p value of <0.001 and CI=95% and a mean difference of 17.05 (14.91-19.21) for
LVEDD with a p value of 0.001 and CI=95%.
In the present study, serum zinc levels were measured in 30 patients with ischemic cardiomyopathy, 18 patients with idiopathic dilated cardiomyopathy and 27 healthy volunteers as control group. There was no statistically significant difference between
serum Zinc level in control and cardiomyopathy group (P>0.05).
Trace elements are known to have a key role in myocardial metabolism.1 Research about the role of Zinc in cardiomyopathy is listed in table 3. Zinc is part of several enzymes like superoxide dismutase and glutation peroxidase.11 In superoxide dismutase, deficiencies in superoxide anions will react with hydrogen peroxide and produce hydroxide radicals, which react with cell membrane lipids and induce cell damage. Zinc and even copper have a protective role against free radicals and thus have a preventive role in cardiovascular diseases.11 In heart failure, activation of atrial natriuric peptide will induce high urine Zinc excretion, which reduces serum and RBC Zinc levels. Zinc deficiency will affect myocardial performance.
Kosan and colleagues reported that IDCMP serum Zinc level was less than that observed in the control group with a P value of (P=0.000). Topuzoglu and colleagues4 and Ripa and colleagues12 reported the same results.
Chou and colleagues7 on the other hand did not show any difference between serum Zinc level in IDSMP and control group. In our study, serum Zinc level in IDSMP patients was less than control group (0.97±0.25 in patient group comparing with1.12±0.41 in control group) which was not statistically significant with a p value 0.17.
Low serum Zinc level was reported 8,9,13 in the ischemic cardiomyopathy group as well, but with a (1.05±0.27 in patient group comparing with 1.12±0.41 in control group) p value of 0.41; our study did not show any statistically significant results.
In 1995, Powell and colleagues14 reported Zinc supplementation of St Thomas’s cardiopledgia solution would enhance its protective effectiveness in in-vitro hypothermic cardiac arrest.
Then in 2007, Karagulova and colleagues15 reported a protective role for intracellular Zinc in ischemia reperfusion heart.
In our study, we measured serum Zinc level. Measuring intracellular Zinc may give us a better clue regarding its role in pathogenesis and the potential therapeutic use of Zinc supplementation in cardiomyopathy.
This study showed serum Zinc level might not have a role in pathogenesis of Ischemic and dilated cardiomyopathy. As Intracellular Zinc levels play a role in heart subjected to ischemia- reperfusion, measuring intracellular Zinc may give us a better clue about the role of Zinc or other trace elements in pathogenesis of cardiomyopathy.
This study has been supported by Mazandaran University of Medical Sciences.
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