Protection by coenzyme Q10 from myocardial reperfusion injury during coronary artery bypass grafting

Comparison of Coenzyme Q10 (Ubiquinone) and Reduced Coenzyme Q10 (Ubiquinol) as Supplement to Prevent Cardiovascular Disease and Reduce Cardiovascular Mortality

PURPOSE OF REVIEW

According to the World Health Organization (WHO), cardiovascular disease is the leading cause of death worldwide. Heart failure has been defined as a global pandemic leading to millions of deaths. Recent research clearly approved the beneficial effect of Coenzyme Q10 supplementation in treatment and prevention of cardiovascular disease in patients with heart failure in clinical trials but did not distinguish between the oxidised form CoQ10 and reduced form CoQH2 of Coenzyme Q10. The aim of this study is to determine differences in medical application of CoQ10 and CoQH2 supplementation and evaluate the efficacy of CoQ10 and CoQH2 supplementation to prevent cardiovascular disease in patients with heart failure.

RECENT FINDINGS

A PubMed search for the terms "ubiquinone" and "ubiquinol" was conducted, and 28 clinical trials were included. Our findings go along with the biochemical description of CoQ10 and CoQH2, recording cardiovascular benefits for CoQ10 and antioxidative and anti-inflammatory properties for CoQH2. Our main outcomes are the following: (I) CoQ10 supplementation reduced cardiovascular death in patients with heart failure. This is not reported for CoQH2. (II) Test concentrations leading to cardiovascular benefits are much lower in CoQ10 studies than in CoQH2 studies. (III) Positive long-term effects reducing cardiovascular mortality are only observed in CoQ10 studies. Based on the existing literature, the authors recommend CoQ10 instead of CoQH2 to treat and prevent cardiovascular disease in patients with heart failure.

The physiological insight of Coenzyme-Q10 administration in preventing the incidence of reperfusion arrhythmia among patients undergoing coronary artery bypass grafting surgery

Reperfusion arrhythmia following cardiac surgery has long been studied as part of myocardial damage. Reperfusion injury is thought to be exacerbated by oxygen-free radicals, whereas arrhythmogenic oscillations in membrane potential are mediated by reactive oxygen. Coenzyme Q10 is a lipid-soluble antioxidant that inhibits lipid peroxidation in biological membranes and supplies ATP cell synthesis, required as the organism's primary energy source. This process explains how Coenzyme Q10 helps stabilize membranes and avoids critical metabolite depletion that may relate to reperfusion arrhythmia. There is a reduction of iatrogenic Coenzyme Q10 after coronary artery bypass surgery (CABG). On the other hand, there is an increased inflammatory process and cellular demand post CABG procedure. It leads to ischemia that can be manifested as arrhythmia. Reperfusion arrhythmia was less common in patients who took Coenzyme Q10. These findings suggest that Coenzyme Q10 supplementation might help patients with heart surgery avoid reperfusion arrhythmia. However, a higher-quality randomized controlled study is needed to determine the effect of Coenzyme Q10 in preventing reperfusion arrhythmia in cardiac surgery patients.

Coenzyme Q10 Reduces Infarct Size in Animal Models of Myocardial Ischemia-Reperfusion Injury: A Meta-Analysis and Summary of Underlying Mechanisms

Objective

Effective interventions that might limit myocardial ischemia-reperfusion (I/R) injury are still lacking. Coenzyme Q₁₀ (CoQ₁₀) may exert cardioprotective actions that reduce myocardial I/R injury. We conducted this meta-analysis to assess the potential cardioprotective effect of CoQ₁₀ in animal models of myocardial I/R injury.

Methods

We searched PubMed and Embase databases from inception to February 2022 to identify animal studies that compared the effect of CoQ₁₀ with vehicle treatment or no treatment on myocardial infarct size in models of myocardial I/R injury. Means and standard deviations of the infarct size measurements were pooled as the weighted mean difference with 95% confidence interval (CI) using the random-effects model. Subgroup analyses were also conducted according to animals' species, models' type, and reperfusion time.

Results

Six animal studies (4 in vivo and 2 ex vivo) with 116 animals were included. Pooled analysis suggested that CoQ₁₀ significantly reduced myocardial infarct size by −11.36% (95% CI: −16.82, −5.90, p < 0.0001, I² = 94%) compared with the control group. The significance of the pooled effect estimate was maintained in rats, Hartley guinea pigs, and Yorkshire pigs. However, it became insignificant in the subgroup of rabbits −5.29% (95% CI: −27.83, 17.26; I² = 87%). Furthermore, CoQ₁₀ significantly reduced the myocardial infarct size regardless of model type (either in vivo or ex vivo) and reperfusion time (either ≤ 4 h or >4 h).

Conclusion

Coenzyme Q₁₀ significantly decreased myocardial infarct size by 11.36% compared with the control group in animal models of myocardial I/R injury. This beneficial action was retained regardless of model type and reperfusion time.

Combating Ischemia-Reperfusion Injury with Micronutrients and Natural Compounds during Solid Organ Transplantation: Data of Clinical Trials and Lessons of Preclinical Findings

Although extended donor criteria grafts bear a higher risk of complications such as graft dysfunction, the exceeding demand requires to extent the pool of potential donors. The risk of complications is highly associated with ischemia-reperfusion injury, a condition characterized by high loads of oxidative stress exceeding antioxidative defense mechanisms. The antioxidative properties, along with other beneficial effects like anti-inflammatory, antiapoptotic or antiarrhythmic effects of several micronutrients and natural compounds, have recently emerged increasing research interest resulting in various preclinical and clinical studies. Preclinical studies reported about ameliorated oxidative stress and inflammatory status, resulting in improved graft survival. Although the majority of clinical studies confirmed these results, reporting about improved recovery and superior organ function, others failed to do so. Yet, only a limited number of micronutrients and natural compounds have been investigated in a (large) clinical trial. Despite some ambiguous clinical results and modest clinical data availability, the vast majority of convincing animal and in vitro data, along with low cost and easy availability, encourage the conductance of future clinical trials. These should implement insights gained from animal data.

Coenzyme Q10 in Cardiovascular and Metabolic Diseases: Current State of the Problem

The burden of cardiovascular and metabolic diseases is increasing with every year. Although the management of these conditions has improved greatly over the years, it is still far from perfect. With all of this in mind, there is a need for new methods of prophylaxis and treatment. Coenzyme Q10 (CoQ10) is an essential compound of the human body. There is growing evidence that CoQ10 is tightly linked to cardiometabolic disorders. Its supplementation can be useful in a variety of chronic and acute disorders. This review analyses the role of CoQ10 in hypertension, ischemic heart disease, myocardial infarction, heart failure, viral myocarditis, cardiomyopathies, cardiac toxicity, dyslipidemia, obesity, type 2 diabetes mellitus, metabolic syndrome, cardiac procedures and resuscitation.

Ubiquinol (Reduced Coenzyme Q10) and Cellular Oxygen Consumption in Patients Undergoing Coronary Artery Bypass Grafting

Ubiquinol is a fundamental component of cellular metabolism. Low ubiquinol levels have been associated with mortality. This was a substudy of a randomized trial in patients undergoing coronary artery bypass grafting. We drew blood before and after surgery. Ubiquinol or placebo was added to peripheral blood mononuclear cells for oxygen consumption (OCR) measurements. In vivo ubiquinol levels were lower postsurgery compared to presurgery (0.16 μmol/L [quartiles: 0.02-0.39], P = .01), although the difference disappeared when adjusting for hemoglobin levels (P = .30). There was no difference in presurgical basal (1.0 mL/min/mg [95% confidence interval [CI]: -0.9 to 2.2], P = .08) and maximal (0.5 mL/min/mg [95% CI: -4.3 to 7.3], P = .56) OCR in cells receiving ubiquinol or placebo. There was a difference in postsurgical basal (1.1 mL/min/mg [95% CI: 0.9-1.6], P < .001) and maximal (4.2 mL/min/mg [95% CI: 0.3-7.0], P = .01) OCR between the groups. We found no association between ubiquinol and OCR levels (all P > .05).

The role of noninvasive cardiovascular testing, applied clinical nutrition and nutritional supplements in the prevention and treatment of coronary heart disease

Numerous clinical trials suggest that we have reached a limit in our ability to decrease the incidence of coronary heart disease (CHD) and cardiovascular disease (CVD) utilizing the traditional diagnostic evaluation, prevention and treatment strategies for the top five cardiovascular risk factors of hypertension, diabetes mellitus, dyslipidemia, obesity and smoking. About 80% of heart disease (heart attacks, angina, coronary heart disease and congestive heart failure) can be prevented by optimal nutrition, optimal exercise, optimal weight and body composition, mild alcohol intake and avoiding smoking. Statistics show that approximately 50% of patients continue to have CHD or myocardial infarction (MI) despite presently defined 'normal' levels of the five risk factors listed above. This is often referred to as the 'CHD gap'. Novel and more accurate definitions and evaluations of these top five risk factors are required, such as 24 h ambulatory blood pressure (ABM) results, advanced lipid profiles, redefined fasting and 2 h dysglycemia parameters, a focus on visceral obesity and body composition and the effects of adipokines on cardiovascular risk. There are numerous traumatic insults from the environment that damage the cardiovascular system but there are only three finite vascular endothelial responses, which are inflammation, oxidative stress and immune vascular dysfunction. In addition, the concept of translational cardiovascular medicine is mandatory in order to correlate the myriad of CHD risk factors to the presence or absence of functional or structural damage to the vascular system, preclinical and clinical CHD. This can be accomplished by utilizing advanced and updated CV risk scoring systems, new and redefined CV risk factors and biomarkers, micronutrient testing, cardiovascular genetics, nutrigenomics, metabolomics, genetic expression testing and noninvasive cardiovascular testing.

The randomized clinical trial of coenzyme Q10 for the prevention of periprocedural myocardial injury following elective percutaneous coronary intervention

INTRODUCTION

Periprocedural myocardial injury (PMI) following elective percutaneous coronary intervention (PCI) is an important therapeutic concern with remaining some mortality and morbidity. To the best of our knowledge, there is no published study that investigates the potential benefit of CoQ10 in preventing PMI following elective PCI.

METHODS

In a randomized, clinical trial, 100 patients who scheduled for elective PCI were allocated in to the intervention (n=50) and control group (n=50). The intervention received a 300 mg loading dose CoQ10 12 hours before procedure. The level of CK-MB and troponin-I was measured before procedure, and 8 and 24 hours after. Furthermore, hs-CRP was measured at baseline and 24 hours after. All patients were assessed for the incidence of major adverse cardiac effects (MACEs) after 1 month.

RESULTS

The CK-MB elevation (above the upper limit normal) was occurred in 22% (n=11) of CoQ10 and 20% (n=10) of control (P=.806). The elevation of troponin-I was documented in 8% (n=4) of both groups. No significant change in the level of cardiac biomarkers was noted. However, the significant reduction in hs-CRP level was occurred in CoQ10 group (P=.032).

CONCLUSION

The results showed that pretreatment with 300 mg CoQ10 12 hours before procedure could not reduce PMI following elective PCI, however, significantly decreased hs-CRP.

The protective role of coenzyme Q10 in renal injury associated with extracorporeal shockwave lithotripsy: a randomised, placebo-controlled clinical trial

OBJECTIVE

To determine the efficacy of coenzyme Q10 (CoQ10) in preventing renal injury in patients with lithiasis undergoing extracorporeal shockwave lithotripsy (ESWL).

PATIENTS AND METHODS

Prospective, randomised, double-blind, placebo-controlled clinical trial of 100 patients with renal lithiasis who were treated with ESWL. The patients were distributed randomly into two groups receiving either placebo or CoQ10 (200 mg/day), a powerful antioxidant with vasoactive properties, orally administered during the week before ESWL and for 1 week after. Renal dysfunction markers, vasoactive hormones, oxidative stress, plasma levels of several interleukins and vascular resistance index (VRI) using Doppler ultrasound were evaluated the week before ESWL, 2 h before ESWL and at 2 h, 24 h and 7 days after ESWL.

RESULTS

There was a significant increase in glomerular filtration (P = 0.013), as well as a decrease in the albumin/creatinine ratio and the β2 -microglobulin level (P = 0.02) after 1 week of treatment in the CoQ10 group. These changes were maintained at the follow-up after ESWL. The administration of CoQ10 was associated with improvement in vasoactive hormone parameters, VRI and interleukin levels. These improvements were maintained until the end of the follow-up period. However, the administration of CoQ10 was not associated with significant changes in the oxidative stress parameters.

CONCLUSION

Our results indicate that CoQ10 administration improves renal function and vasoactive and inflammation parameter values, allowing for preconditioning before the tissue insult caused by ESWL.

Evaluation of anti-angiogenic, anti-inflammatory and antinociceptive activity of coenzyme Q10 in experimental animals

Objectives

This work aimed to assess some pharmacological activities of coenzyme Q10 (CoQ10) in animal experimental models.

Methods

The chick chorioallantoic membrane assay was used to evaluate anti-angiogenic activity of CoQ10. Anti-inflammatory activity of CoQ10 was confirmed using two animal models of inflammation. These were the vascular permeability and air pouch models, models of acute and sub-acute inflammation, respectively. Antinociceptive activity was assessed by the acetic acid-induced abdominal constriction response.

Key findings

CoQ10 dose-dependently displayed inhibition of chick chorioallantoic membrane angiogenesis. In the acetic acid-induced vascular permeability model in mice, CoQ10 at 50, 100 and 200 mg/kg reduced vascular permeability from 0.74 ± 0.01 (A590) to 0.67 ± 0.01 (P &lt; 0.01), 0.46 ± 0.02 (P &lt; 0.01) and 0.30 ± 0.01 (P &lt; 0.01), respectively. In the carrageenan-induced inflammation in the air pouch, CoQ10 was able to diminish exudate volume, the number of polymorphonulcear leucocytes and nitrite content in the air pouches. CoQ10 at 25, 50 and 100 mg/kg significantly reduced acetic acid-induced abdominal constriction in mice from 27.0 ± 2.00 (number of abdominal constrictions) to 17.7 ± 0.33 (P &lt; 0.01), 9.3 ± 0.67 (P &lt; 0.01) and 1.3 ± 0.33 (P &lt; 0.01), respectively, suggesting a strong antinociceptive activity.

Conclusions

CoQ10 possessed considerable anti-angiogenic, anti-inflammatory and antinociceptive activity, possibly via down-regulating the level of nitric oxide, which partly supported its use as a dietary supplement and in combination therapy.

The role of oral coenzyme Q10 in patients undergoing coronary artery bypass graft surgery

OBJECTIVE

Cardiopulmonary bypass (CPB) is known to induce oxidative stress. Because total antioxidant level is reduced during CPB, the supplementation of an antioxidant might help in attenuating the oxidative stress response. The authors sought to evaluate the efficacy of oral coenzyme Q10, in attenuating the oxidative stress to CPB and altering the clinical outcome in patients undergoing coronary artery bypass graft (CABG) surgery.

DESIGN

A prospective, randomized, single-center clinical study.

SETTING

A cardiothoracic center of a tertiary hospital.

PARTICIPANTS

Thirty patients scheduled for elective CABG surgery.

INTERVENTIONS

The study group (n = 15) received oral coenzyme Q10, 150 to 180 mg/d, for 7 to 10 days preoperatively, whereas the control group (n = 15) did not receive any antioxidant or placebo. The anesthesia technique was standardized in both groups. Blood samples for total antioxidant level, blood glucose level, and clinical outcome parameters up to 24 hours postoperatively were compared.

MEASUREMENTS AND MAIN RESULTS

There was no difference in the antioxidant level between the 2 groups at any point of time. However, in the study group, 24 hours after aortic clamp release, it was significantly higher than baseline (p < 0.05). The blood glucose was significantly lower in the study group at aortic clamp removal and 4 hours after clamp removal as compared with the control group (p = 0.01). The study group had significantly fewer reperfusion arrhythmias, lower total inotropic requirement, mediastinal drainage, blood product requirement, and shorter hospital stays compared with the control group.

CONCLUSION

Oral coenzyme Q10 therapy for 7 to 10 days preoperatively could improve clinical outcome in patients undergoing CABG surgery. A larger study group is recommended for confirmation.

Do N-acetylcystein, beta-glucan, and coenzyme Q10 mollify myocardial ischemia-reperfusion injury?

BACKGROUND

N-acetylcysteine, beta-glucan, and coenzyme Q10 have been shown to have antioxidant and anti-inflammatory effects on reperfusion injury. The aim of our study was to determine and evaluate the effects of these agents on myocardial ischemia-reperfusion injury.

METHODS

Forty-four New Zealand white rabbits, all female, weighing 2.4 to 4.1 kg (mean, 3.6 kg) were used in the study. Four study groups of 11 animals were arranged by randomization. The groups were the control group (group C), a group premedicated with coenzyme Q10 (group Q), a group premedicated with beta-glucan (group betaT), and a group premedicated with N-acetylcysteine (group N). After exploration of the heart, a basal myocardial biopsy was taken from the anteroapical left ventricle, and the first blood sampling was done before ischemia. For the ischemia-reperfusion experiments, the major left anterior descending artery was occluded after baseline measurements. After a 45-minute transient ischemic period, the heart was perfused for 120 minutes. After perfusion, the second myocardial biopsy was taken from the anteroapical left ventricle, and the second blood sampling was done. Blood and tissue analysis were performed and evaluated statistically.

RESULTS

Baseline and reperfusion levels of glutathione peroxidase, superoxide dismutase, malonyldialdehyde, and nitric oxide changed significantly. While malonyldialdehyde levels increased in group C, they decreased in the other study groups (P =.001). The increases in glutathione peroxidase and superoxide dismutase levels were significant in all groups except group C (P =.0001 and P <.05, respectively). Levels of nitric oxide were found to be decreased in group C, whereas they increased in the other groups (P =.001).

CONCLUSION

Antioxidant medication may help in lowering the risk of myocardial ischemia-reperfusion injury. All the medications in our study are shown to have effective roles in preventing ischemia-reperfusion injury to some extent through their antioxidant properties.

Protective effect of coenzyme Q10-loaded liposomes on the myocardium in rabbits with an acute experimental myocardial infarction

PURPOSE

We assessed whether the infusion of Coenzyme Q10-loaded liposomes (CoQ10-L) in rabbits with an experimental myocardial infarction can result in increased intracellular delivery of CoQ10 and thus limit the fraction of the irreversibly damaged myocardium.

METHODS

CoQ10-L, empty liposomes (EL), or Krebs-Henseleit (KH) buffer were administered by intracoronary infusion, followed by 30 min of occlusion and 3 h of reperfusion. Unisperse Blue dye was used to demarcate the net size of the occlusion-induced ischemic zone ("area at risk") while nitroblue tetrazolium staining was used to detect the final fraction of the irreversibly damaged myocardium within the total area at risk.

RESULTS

The total size of the area at risk in all experimental animals was approx. 20% wt. of the left ventricle (LV). The final irreversible damage in CoQ10-L-treated animals was only ca. 30% of the total area at risk as compared with ca. 60% in the group treated with EL (p < 0.006) and ca. 70% in the KH buffer-treated group (p < 0.001).

CONCLUSIONS

CoQ10-L effectively protected the ischemic heart muscle by enhancing the intracellular delivery of CoQ10 in hypoxic cardiocytes in rabbits with an experimental myocardial infarction as evidenced by a significantly decreased fraction of the irreversibly damaged heart within the total area at risk. CoQ10-L may provide an effective exogenous source of the CoQ10 in vivo to protect ischemic cells.

Coenzyme Q10 in cardiovascular disease

In this review we summarise the current state of knowledge of the therapeutic efficacy and mechanisms of action of CoQ(10) in cardiovascular disease. Our conclusions are: 1. There is promising evidence of a beneficial effect of CoQ(10) when given alone or in addition to standard therapies in hypertension and in heart failure, but less extensive evidence in ischemic heart disease. 2. Large scale multi-centre prospective randomised trials are indicated in all these areas but there are difficulties in funding such trials. 3. Presently, due to the notable absence of clinically significant side effects and likely therapeutic benefit, CoQ(10) can be considered a safe adjunct to standard therapies in cardiovascular disease.

Protective effects of antioxidant medications on limb ischemia reperfusion injury

BACKGROUND

N-acetylcysteine, beta-glucan, and coenzyme Q(10) were shown to have antioxidant and anti-inflammatory effects on reperfusion injury. The aim of our study was to determine and evaluate the effects of these agents on ischemia reperfusion injury of limb.

MATERIAL AND METHOD

Forty-four New Zealand white rabbits, all female, weighing between 2.3 to 4.2 (mean 3.8) kg, were used in the study. Four study groups were arranged of 11 animals each, by randomization. The first group was the control group (Group C), the other groups were the Group Q, which was medicated with coenzyme Q10, the Group betaG, which was medicated with beta-glucan, and the Group N, medicated with N-acetylcysteine. After baseline measurements, for the ischemia-reperfusion experiments, common iliac artery was clamped and collateral flow was occluded by a rubber arterial tourniquet wrapped around the thigh at the proximal third of the leg. After 60 min of transient ischemic period, the limb was perfused for 180 min. After perfusion, biopsy was taken from the adductor magnus muscle. Second blood sampling was done after reperfusion period. Blood and tissue analysis were done and evaluated statistically.

RESULTS

Baseline and post-reperfusion levels of glutathione peroxidase (GPx), super oxide dismutase (SOD), malonyldialdehyde (MDA), and nitric oxide (NO) changed significantly. While MDA levels increased in the control group, it decreased in the other study groups. The increase in GPx and SOD levels were significant in all groups except the control group. Levels of NO were found to have decreased in the control group, whereas it had increased in the other groups.

CONCLUSION

Antioxidant medication may help lowering limb ischemia reperfusion injury. All mentioned medications in our study are shown to be able to have an effective role for preventing ischemia reperfusion injury to some extent through their antioxidant properties.

Risk assessment for coenzyme Q10 (Ubiquinone)

Coenzyme Q10 (CoQ10) widely occurs in organisms and tissues, and is produced and used as both a drug and dietary supplement. Increasing evidence of health benefits of orally administered CoQ10 are leading to daily consumption in larger amounts, and this increase justifies research and risk assessment to evaluate the safety. A large number of clinical trials have been conducted using a range of CoQ10 doses. Reports of nausea and other adverse gastrointestinal effects of CoQ10 cannot be causally related to the active ingredient because there is no dose-response relationship: the adverse effects are no more common at daily intakes of 1200 mg than at a 60 mg. Systematic evaluation of the research designs and data do not provide a basis for risk assessment and the usual safe upper level of intake (UL) derived from it unless the newer methods described as the observed safe level (OSL) or highest observed intake (HOI) are utilized. The OSL risk assessment method indicates that the evidence of safety is strong at intakes up to 1200 mg/day, and this level is identified as the OSL. Much higher levels have been tested without adverse effects and may be safe, but the data for intakes above 1200 mg/day are not sufficient for a confident conclusion of safety.

Coenzyme Q10 therapy before cardiac surgery improves mitochondrial function and in vitro contractility of myocardial tissue

OBJECTIVES

Previous clinical trials suggest that coenzyme Q(10) might afford myocardial protection during cardiac surgery. We sought to measure the effect of coenzyme Q(10) therapy on coenzyme Q(10) levels in serum, atrial trabeculae, and mitochondria; to assess the effect of coenzyme Q(10) on mitochondrial function; to test the effect of coenzyme Q(10) in protecting cardiac myocardium against a standard hypoxia-reoxygentation stress in vitro; and to determine whether coenzyme Q(10) therapy improves recovery of the heart after cardiac surgery.

METHODS

Patients undergoing elective cardiac surgery were randomized to receive oral coenzyme Q(10) (300 mg/d) or placebo for 2 weeks preoperatively. Pectinate trabeculae from right atrial appendages were excised, and mitochondria were isolated and studied. Trabeculae were subjected to 30 minutes of hypoxia, and contractile recovery was measured. Postoperative cardiac function and troponin I release were assessed.

RESULTS

Patients receiving coenzyme Q(10) (n = 62) had increased coenzyme Q(10) levels in serum (P = .001), atrial trabeculae (P = .0001), and isolated mitochondria (P = .0002) compared with levels seen in patients receiving placebo (n = 59). Mitochondrial respiration (adenosine diphosphate/oxygen ratio) was more efficient (P = .012), and mitochondrial malondialdehyde content was lower (P = .002) with coenzyme Q(10) than with placebo. After 30 minutes of hypoxia in vitro, pectinate trabeculae isolated from patients receiving coenzyme Q(10) exhibited a greater recovery of developed force compared with those in patients receiving placebo (46.3% +/- 4.3% vs 64.0% +/- 2.9%, P = .001). There was no between-treatment difference in preoperative or postoperative hemodynamics or in release of troponin I.

CONCLUSIONS

Preoperative oral coenzyme Q(10) therapy in patients undergoing cardiac surgery increases myocardial and cardiac mitochondrial coenzyme Q(10) levels, improves mitochondrial efficiency, and increases myocardial tolerance to in vitro hypoxia-reoxygenation stress.

Lifestyle and dietary modification for prevention of heart failure

This article discusses the factors that contribute most to systolic and diastolic heart failure (HF): ischemic heart disease, hypertension,obesity, diabetes, and nephropathy. Diabetes often follows the insulin resistance syndrome in which obesity and hypertension are combined with dyslipidemia, and obesity is likely causal. Diabetes and hypertension are common causes of nephropathy, which in turn is a common precursor to HF. Insulin resistance, obesity,dyslipidemia, diabetes, and hypertension are risk factors for atherosclerotic coronary disease and left ventricular ischemia. Each is also a risk factor for diastolic dysfunction.

Comparison between warm blood and crystalloid cardioplegia during open heart surgery

OBJECTIVE

This study was designed to compare the degree of myocardial protection afforded by warm blood and cold crystalloid cardioplegia in a group of patients undergoing elective coronary artery bypass surgery.

METHODS

Seventeen patients, were randomly assigned to Group A (n=9), who received crystalloid cardioplegic solution, and Group B who received warm blood cardioplegic solution (n=8). Before the aorta was clamped, and 10 min after reperfusion, blood samples from the coronary sinus were obtained to assay alpha-tocopherol, beta-carotene, ubiquinol, and thiobarbituric acid reactive substances (TBARS). At the same intervals, biopsies from the left ventricle were obtained to determine ultrastructural alterations.

RESULTS

No significant changes were observed between preischemia and reperfusion values for both blood and crystalloid groups concerning alpha-tocopherol, beta-carotene, and ubiquinol, and no differences between groups were detected. Values for TBARS in group A were 3.49+/-0.3 and 5.27+/-0.45 microM for presichemia and reperfusion samples, respectively (P<0.01). In group B values were 2.6+/-0.3 and 3.54+/-0.3 microM, respectively (P=NS). For electron microscopy studies, semiquantitative analysis showed a significant mitochondrial damage in reperfusion biopsies from group A (grades 0, 3 and 4). In group B, no significant changes were observed in mitochondrial damage between preischemia and repefusion biopsies (except for grade 0).

CONCLUSION

These results indicate that blood cardioplegia affords better protection to the myocyte than crystalloid cardioplegia.

Cardiovascular disease

The primary care physician is in a position to advise patients on the efficacy of alternative and complementary therapies as they relate to cardiovascular diseases. Anti-oxidant vitamin supplementation has not been shown to be efficacious in decreasing cardiovascular events. N-3 fatty acids appear to be beneficial in secondary prevention of cardiovascular events but their use in primary prevention is not clear. Adoption of vegetable-based diets, including whole grains, can be recommended to decrease cardiovascular events, lower cholesterol and help lower blood pressure. For patients with hypercholesterolemia, cholestin, a red-yeast rice supplement, has been shown to be effective. Garlic supplements may have some mild cholesterol-lowering effect, but this effect is not significant enough to recommend clinically. Herbal therapies with hawthorn and ubiquinone (Q10) are of possible benefit in congestive heart failure. An integrated program of rigorous diet, exercise and stress reduction in motivated patients with cardiovascular disease may have value as an alternative to cardiovascular medications and surgical interventions.

Similar therapeutic serum levels attained with emulsified and oil-based preparations of coenzyme Q10

Studies of the therapeutic efficacy of coenzyme Q10 (CoQ10) have been confounded by the variable bioavailability of numerous CoQ10 preparations. The aims of the present study were to determine the early serum levels attained by two different preparations of CoQ10, a soybean oil-based preparation and a complex micelle emulsion and to assess whether these preparations of oral CoQ10 influence plasma lipid profiles. Twelve healthy individuals received 300 mg CoQ10 daily of either preparation for 7 days in a double-blind cross-over design with a 21-day washout period. Blood samples to determine serum levels of CoQ10 and lipids were taken at baseline, after 24 h and 7 days. Both preparations induced significant increases in serum CoQ10 levels at 24 h and 7 days. These were for soy oil: baseline 0.27 +/- 0.03 mol/L, 24 h 0.50 +/- 0.04 mol/L (180%) and 7 days 0.80 +/- 0.05 mol/L (291%), mean +/- SEM: for emulsion: baseline 0.29 +/- 0.03 mol/L, 24 h 0.45 +/- 0.03 mol/L (150%) and 7 days 0.79 +/- 0.06 mol/L (270%). There were no significant differences between CoQ10 levels for the two preparations at either time point. There was no change in any of the serum lipids following the 7 days treatment. We conclude that administration of either a soy oil suspension or a complex emulsion of CoQ10 increases serum levels to the therapeutic range within 1 week.

Effect of coenzyme Q10 supplementation on mitochondrial function after myocardial ischemia reperfusion

BACKGROUND

Coenzyme Q10 (CoQ10) protects myocardium from ischemia-reperfusion (IR) injury as evidenced by improved recovery of mechanical function, ATP, and phosphocreatine during reperfusion. This protection may result from CoQ10's bioenergetic effects on the mitochondria, from its antioxidant properties, or both. The purpose of this study was to elucidate the effects of CoQ10 supplementation on mitochondrial function during myocardial ischemia-reperfusion using an isolated mitochondrial preparation.

METHODS

Isolated hearts (n = 6/group) from rats pretreated with liposomal CoQ10 (10 mg/kg iv, CoQ10), vehicle (liposomal only, Vehicle), or saline (Saline) 30 min before the experiments were subjected to 15 min of equilibration (EQ), 25 min of ischemia (I), and 40 min of reperfusion (RP). Left ventricular-developed pressure (DP) was measured. Mitochondria were isolated at end-equilibration (end-EQ), at end-ischemia (end-I), and at end-reperfusion (end-RP). Mitochondrial respiratory function (State 2, 3, and 4, respiratory control index (RCI, ratio of State 3 to 4), and ADP:O ratio) was measured by polarography using NADH (alpha-ketoglutarate, alpha-KG)- or FADH (succinate, SA)-dependent substrates.

RESULTS

CoQ10 improved recovery of DP at end-RP (67 +/- 11% in CoQ10 vs 47 +/- 5% in Vehicle and 50 +/- 11% in Saline, P < 0.05 vs Vehicle and Saline). CoQ10 did not change preischemic mitochondrial function. IR decreased State 3 and RCI in all groups using either substrate. CoQ10 had no effect in the mitochondrial oxidation of alpha-KG at end-I. CoQ10 improved State 3 at end-I when SA was used (167 +/- 21 in CoQ10 vs 120 +/- 10 in Saline and 111 +/- 10 ng-atoms O/min/mg protein in Vehicle, P < 0.05). Using alpha-KG as a substrate, CoQ10 improved RCI at end-RP (4.2 +/- 0.2 in CoQ10 vs 3.2 +/- 0.2 in Saline and 3.0 +/- 0.3 in Vehicle, P < 0.05). Using SA, CoQ10 improved State 3 (181 +/- 10 in CoQ10 vs 142 +/- 9 in Saline and 140 +/- 12 ng-atoms O/min/mg protein in Vehicle, P < 0.05) and RCI (2.21 +/- 0.06 in CoQ10 vs 1.85 +/- 0.11 in Saline and 1.72 +/- 0.08 in Vehicle, P < 0.05) at end-RP.

CONCLUSIONS

The cardioprotective effects of CoQ10 can be attributed to the preservation of mitochondrial function during reperfusion as evidenced by improved FADH-dependent oxidation.

Pathobiology and Clinical Impact of Reperfusion Injury

Reperfusion injury refers to cellular death or dysfunction caused by restoration of blood flow to previously alchemic tissue. This should be differentiated from the normal reparative processes that follow an ischemic insult. Four types of reperfusion injury have been described in the literature: (1) lethal reperfusion injury, (2) nonlethal reperfusion injury, (myocardial stunning), (3) reperfusion arrhythmias, and (4) vascular injury (including the "no-reflow" phenomenon). There is continued debate whether reperfusion itself is capable of killing viable myocytes, which otherwise would have survived the ischemic insult. However, there is firm evidence for the existence of myocardial stunning following various ischemic syndromes, including reperfusion therapy for acute myocardial infarction, unstable angina pectoris, vasospastic angina, effort-induced ischemia, coronary artery bypass surgery, and cardiac transplantation. Reperfusion arrhythmia is more common after short ischemic episodes than after long ischemic periods. Thus, while reperfusion arrhythmias in the setting of acute myocardial infarction are relatively rare, reperfusion arrhythmias may be an important cause of sudden death. The "no-reflow" phenomenon has been described following reperfusion in patients with acute myocardial infarction. Three major components have been proposed as mediators of reperfusion injury: (1) oxygen free radicals, (2) the complement system, and (3) neutrophils. Numerous experimental studies have shown short-term benefit by blocking various stages of the postischemic inflammatory response. Oxygen free radicals scavengers, complement inhibition, leukocyte depletion, and the use of antibodies against various adhesion molecules have shown a reduction of infarct size in many ischemic/reperfusion experimental models. However, many of these agents failed to show a benefit in the clinical setting. Moreover, the long-term benefit of such intervention is still unknown.

Pathobiology and Clinical Impact of Reperfusion Injury

Reperfusion injury refers to cellular death or dysfunction caused by restoration of blood flow to previously ischemic tissue. This should be differentiated from the normal reparative processes that follow an ischemic insult. Four types of reperfusion injury have been described in the literature: (1) lethal reperfusion injury, (2) nonlethal reperfusion injury (myocardial stunning), (3) reperfusion arrhythmias, and (4) vascular injury (including the "no-reflow" phenomenon). There is continued debate whether reperfusion itself is capable of killing viable myocytes, which otherwise would have survived the ischemic insult. However, there is firm evidence for the existence of myocardial stunning following various ischemic syndromes, including reperfusion therapy for acute myocardial infarction, unstable angina pectoris, vasospastic angina, effort-induced ischemia, coronary artery bypass surgery, and cardiac transplantation. Reperfusion arrhythmia is more common after short ischemic episodes than after long ischemic periods. Thus, while reperfusion arrhythmias in the setting of acute myocardial infarction are relatively rare, reperfusion arrhythmias may be an important cause of sudden death. The "no-reflow" phenomenon has been described following reperfusion in patients with acute myocardial infarction. Three major components have been proposed as mediators of reperfusion injury: (1) oxygen free radicals, (2) the complement system, and (3) neutrophils. Numerous experimental studies have shown short-term benefit by blocking various stages of the postischemic inflammatory response. Oxygen free radicals scavangers, complement inhibition, leukocyte depletion, and the use of antibodies against various adhesion molecules have shown a reduction of infarct size in many ischemic/reperfusion experimental models. However, many of these agents failed to show a benefit in the clinical setting. Moreover, the long-term benefit of such intervention is still unknown.

Nitecapone as an additive to crystalloid cardioplegia in patients who had coronary artery bypass grafting

BACKGROUND

Nitecapone has been shown to have a protective effect against ischemia-reperfusion injury in experimental heart transplantation and in Langendorff preparations. This prospective, randomized study assessed the effects of nitecapone in patients who had coronary artery bypass grafting.

METHODS

Thirty patients with normal myocardial function were randomly divided into control patients (n = 15), who received crystalloid (Plegisol) cardioplegia, and nitecapone patients, who received nitecapone in a 50 microM solution (n = 15) in Plegisol. Cardioplegia was administered as an initial dose of 15 mL/kg of body mass after cross-clamping and 2 mL/kg every 15 minutes. Simultaneous coronary sinus and aortic blood samples, and myocardial biopsies were taken at 1, 5, and 10 minutes after unclamping. Hemodynamics were measured invasively for 24 hours and with transesophageal echocardiography for 3 hours after cardiopulmonary bypass.

RESULTS

There were no adverse effects. The incidence of ventricular arrhythmias was significantly lower in the treatment group during the recovery period (p = 0.02). Cardiac output and stroke volume did not differ significantly between the groups. The conjugated dienes gradient between the aorta and the coronary sinus increased significantly during the first minute of reperfusion in the control group (p = 0.02) compared with the nitecapone group. Myeloperoxidase activity in myocardial biopsies was higher in the control group (2.3 times higher at 5 minutes and 3.2 times higher at 10 minutes) than in the nitecapone group (p = 0.13).

CONCLUSIONS

Nitecapone did not exert any significant hemodynamic effects in patients with normal ejection fraction.

Overview of the use of CoQ10 in cardiovascular disease

The clinical experience in cardiology with CoQ10 includes studies on congestive heart failure, ischemic heart disease, hypertensive heart disease, diastolic dysfunction of the left ventricle, and reperfusion injury as it relates to coronary artery bypass graft surgery. The CoQ10-lowering effect of HMG-CoA reductase inhibitors and the potential adverse consequences are of growing concern. Supplemental CoQ10 alters the natural history of cardiovascular illnesses and has the potential for prevention of cardiovascular disease through the inhibition of LDL cholesterol oxidation and by the maintenance of optimal cellular and mitochondrial function throughout the ravages of time and internal and external stresses. The attainment of higher blood levels of CoQ10 (> 3.5 micrograms/ml) with the use of higher doses of CoQ10 appears to enhance both the magnitude and rate of clinical improvement. In this communication, 34 controlled trials and several open-label and long-term studies on the clinical effects of CoQ10 in cardiovascular diseases are reviewed.

Effects of short-term supplementation with coenzyme Q10 on myocardial protection during cardiac operations

BACKGROUND

Coenzyme Q10 (CoQ10) is a naturally occurring vitamin-like substance that may have a beneficial role in ischemia-reperfusion injury. Coenzyme Q10 administered either as an additive to cardioplegia or as long-term preoperative oral supplementation has been reported to ameliorate myocardial injury after cardiac operations.

METHODS

To determine whether short-term supplementation with large doses of CoQ10 (600 mg in divided doses 12 hours before operation) was effective in myocardial protection, 20 patients with well-preserved left ventricular function (ejection fraction greater than 0.50) undergoing elective coronary revascularization were enrolled in a prospective, double-blind, placebo-controlled randomized trial. Serial concentrations of CoQ10, myoglobin, creatine kinase MD fraction, and cardiac troponin T were measured preoperatively and 1, 6, 24, 72, and 120 hours postoperatively. Efficacy of myocardial protection was also assessed by clinical outcome and serial changes in electrocardiographic indices.

RESULTS

The patient groups were similar with respect to preoperative and intraoperative characteristics. There was no significant difference in the preoperative plasma levels of CoQ10. These levels fell significantly in both groups after operation, although the magnitude of the decrease was less in the CoQ10-supplemented group (43% versus 60%). In both groups, there were significant postoperative increases in myoglobin, creatine kinase MB fraction, and cardiac troponin T. The magnitude of increases in cardiac troponin T was greater in the CoQ10-supplemented group, reaching marginal overall statistical significance (p = 0.06).

CONCLUSIONS

Short-term supplementation with large doses of CoQ10 does not lead to improved myocardial protection in patients undergoing coronary revascularization with well-preserved ventricular function and relatively short ischemic times.