Department of Emergency Medicine, University La Sapienza, Rome, Italy; Italian Group for the Cardiologic Study of AIDS Patients
Correspondence to: Dr Giuseppe Barbaro, Viale Anicio Gallo 63, 00174 Rome, ItalyE-mail: g.barbaro{at}tin.it
| INTRODUCTION |
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The introduction of highly active antiretroviral therapy (HAART) regimens has greatly modified the course of HIV disease, with longer survival and better quality of life; however, early data from those treated raise concerns about a possible increase in both peripheral and coronary arterial diseases. In global terms HAART is available only to a minority of HIV-infected individuals, and studies before the advent of HAART remain applicable. UNAIDS estimates that 36.1 million people were living with HIV infection at the end of the year 20003. If 9-10% of patients develop symptomatic heart failure over 2-5 years4, then 3 million cases of HIV-related heart failure will present in that time period5. In this review article, I discuss the principal HIV-associated cardiovascular manifestations, with an emphasis on new knowledge about prevalence, pathogenesis and treatment.
| DILATED CARDIOMYOPATHY |
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Myocarditis is the best studied cause of dilated cardiomyopathy in HIV
disease4. HIV
virions infect myocardial cells in patchy
distributions4,7
without a clear direct association between HIV and cardiac myocyte
dysfunction4,7.
How virus enters CD4-receptor-negative cells such as myocytes is unknown.
Reservoir cells (e.g. dendritic cells) may play a pathogenic role in the
interaction between HIV and the myocyte and in the activation of
multifunctional cytokines (e.g. tumour necrosis factor-alpha [TNF-
],
interleukin-1 [IL-1], interleukin-6, interleukin-10) that contribute to
progressive and late tissue
damage6.
Myocarditis and dilated cardiomyopathy are associated with local cytokine
production; thus, circulating levels tend to be
uninformative6.
Viral infection in the context of a nonspecific stimulator of monokines such
as IL-1 or TNF-
is much more likely to lead to myocarditis and myocyte
damage than viral infection alone. TNF-
produces a negative inotropic
effect, by altering intracellular calcium homoeostasis and possibly by
inducing nitric oxide synthesis, which likewise reduces myocyte
contractility6,8.
The intensity of both TNF-
and inducible nitric oxide synthase staining
has been reported much higher in myocardial biopsy samples from patients with
HIV-associated cardiomyopathyspecifically in those with a myocardial
viral infection independently of antiretroviral treatmentthan in those
with idiopathic dilated cardiomyopathy.
When children with HIV-infection have received monthly immunoglobulin
infusions they have shown improvement in left ventricular dysfunction, an
increase in left ventricular wall thickness, and a reduction in peak left
ventricular wall stress; these observations suggest that both impaired
myocardial growth and left ventricular dysfunction are immunologically
mediated9. The
apparent efficacy of immunoglobulin therapy may be due to inhibition of
cardiac autoantibodies (e.g. anti-
-myosin), the prevalence of which is
increased in HIV-infected patients with dilated
cardiomyopathy10,
by competing for Fc receptors; alternatively, immunoglobulins might dampen the
secretion or effects of cytokines and cellular growth
factors11. Further
study is needed to evaluate the efficacy of immunomodulatory therapy in adults
and children with declining left ventricular function. In the published series
there is no evidence of benefit to HIV-associated cardiomyopathy from HAART.
However, the better control of cytomegalovirus infection, which is an
important cause of cardiomyopathy in HIV disease, is one way in which HAART
might lessen the incidence and improve the clinical course of HIV-associated
heart disease. Encephalopathy influences negatively the clinical course of
dilated cardiomyopathy in HIV
disease8. Several
studies have indicated that patients with encephalopathy are more likely to
die of congestive heart failure than are patients without encephalopathy,
hazard ratio after multivariate analysis
3.48. Immune
modulating factors and cytokines have both cardiotoxic and neurotoxic actions
and may play a crucial role in the development and progression of dilated
cardiomyopathy and encephalopathy, perhaps explaining the association between
the two. Proinflammatory cytokines activate inducible NO synthase (iNOS), thus
stimulating production of NO, a sequence of events that may contribute to the
association between dilated cardiomyopathy and encephalopathy in HIV
disease8. HIV can
persist in reservoir cells in the myocardium and the cerebral cortex even
after antiretroviral
treatment8. The
reservoir cells may hold HIV-1 on their surfaces for long periods, and chronic
release of cytotoxic cytokines (e.g. TNF-
, interleukin-6, endothelin-1)
could contribute to progressive and late tissue damage in both systems
independently of HAART
regimens8.
| CORONARY HEART DISEASE AND HYPERTENSION |
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Endothelial dysfunction injury, pivotal to the development of cardiovascular and inflammatory disease, has been described in HIV infection13. There is evidence of endothelial activation, in the form of soluble adhesion molecules and procoagulant proteins13. Virus may gain entry to endothelial cells via CD4 antigen or galactosyl-ceramide receptors. Other possible mechanisms of entry include chemokine receptors. Nevertheless, endothelial activation may also occur via secretion of cytokines in response to mononuclear or adventitial cell activation by virus, or else by the effects of the secreted HIV-associated proteins gp 120 (envelope glycoprotein) and tat (transactivator of viral replication) on endothelium. Enhanced adhesiveness of endothelial cells, endothelial cell proliferation and apoptosis as well as activation of cytokine secretion have all been demonstrated. Selected inflammatory cytokines and viral proteins have been found synergistic in inducing endothelial injury. In HIV infection, dysfunctional or injured endothelial cells potentiate tissue injury, inflammation and remodelling, and accelerate the development of cardiovascular disease13.
Coronary artery disease is observed with increasing frequency among HIV patients receiving therapy with protease inhibitors (PI) in the ambit of HAART regimens1. Despite the clinical benefits of PI therapy, complications such as lipodystrophy, insulin resistance, and high levels of low-density lipoprotein cholesterol and triglyceride develop in up to 60% of patients treated with these regimens1. In 10-20% of patients the effects are severe, with unstable angina, myocardial infarction, and stroke developing even in young individuals14,15,16,17,18.
As regards lipodystrophy, similarities between HIV-associated fat redistribution and metabolic abnormalities with both inherited lipodystrophies and benign symmetric lipomatosis suggest the pathophysiological involvement of nuclear factors such as lamin A/C and drug-induced mitochondrial dysfunction19. Moreover, there is some evidence that cytokines and hormones impair fat and glucose homoeostasis in patients with HIV receiving HAART19. Three years after the first description of HIV-therapy-associated abnormal fat redistribution, there is still discussion about the case definition, diagnostic procedure and treatment options for both body shape changes and metabolic disturbances19.
In the evaluation of patients for HAART and in continued therapy, it is wise to look at traditional coronary risk profiles and to alter those that can be favourably modified. Diet and exercise should not be overlooked, because both can be effective without causing further side-effects20. Fibric acid derivatives and statins can lower HIV-associated hypercholesterolaemia and hypertriglyceridaemia, although further data are needed on interactions between statins and PI20,21. Lovastatin should be avoided in patients receiving drugs that might potentiate the skeletal muscle toxicity of this agent22. Hypoglycaemic agents may have some role in management of glucose abnormalities, although troglitazone cannot be recommended for fat abnormalities alone and metformin may cause lactic acidosis21. Perhaps a better understanding of PI effects on lipid and metabolic pathways will lead to a new generation of drug therapies without metabolic alterations.
HIV patients are at higher risk of becoming hypertensive than the general population, and hypertension develops at a younger age23. Predisposing factors include vasculitis in small, medium, and large vessels in the form of leukocytoclastic vasculitis, atherosclerosis secondary to HAART regimens, and aneurysms of the large vessels such as the carotid and femoral arteries and the abdominal aorta, with impairment of flow to the renal arteries23.
| PULMONARY HYPERTENSION AND RIGHT VENTRICULAR DYSFUNCTION |
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Primary pulmonary hypertension has been reported in HIV-infected patients without a history of thromboembolic disease, intravenous drug use, or pulmonary infections associated with HIV. One necropsy specimen and one biopsy specimen revealed precapillary muscular pulmonary artery and arteriole medial hypertrophy, fibroelastosis, and eccentric intimal fibrosis without direct viral infection of pulmonary artery cells24,25. This suggests mediator release from infected cells elsewhere and possibly cytokine mediated injury.
The pathogenesis of primary pulmonary hypertension is multifactorial and
poorly understood. Primary pulmonary hypertension has been found in
haemophilic patients receiving lyophylized factor VIII, in intravenous drug
users and in patients with left ventricular dysfunction, obscuring any
relationship with the human immunodeficiency
virus1,24,25.
It may be that HIV causes endothelial damage and mediator-related
vasoconstriction through stimulation by the envelope gp 120,
including direct release and effects of endothelin-1 (vasoconstrictor),
interleukin-6 and TNF-
in the pulmonary
arteries24,25.
HIV is frequently identified in alveolar
macrophages24,25.
These macrophages release TNF-
, oxide anions and proteolytic enzymes in
response to infection. Lymphokines may also have a role in the aetiology of
the endothelial proliferation seen in pulmonary hypertension, by promoting
leukocyte adhesion to the
endothelium26.
Clinical symptoms and outcome of patients with right ventricular dysfunction
are related to the degree of pulmonary hypertension, varying from a mild
symptomless condition to severe cardiac impairment with cor pulmonale and
death1,24.
Activation of
1-receptors and genetic factors (increased
frequency of HLA DR6 and DR52) have been also hypothesized for the
pathogenesis of HIV-associated pulmonary
hypertension1,26.
The influence of HAART regimens on the clinical course of HIV-associated
pulmonary hypertension is unknown.
| PERICARDIAL EFFUSION |
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Pericardial effusion in HIV disease may be related to opportunistic
infections (Figure 2) or to
malignancy (Kaposi's sarcoma, non-Hodgkin lymphoma), but most often a clear
aetiology is not
found27. The
effusion may be part of a generalized serous effusive process also involving
pleural and peritoneal surfaces. This capillary leak syndrome is probably
related to enhanced cytokine expression (e.g. TNF-
) in the later stages
of HIV
disease1,27.
Pericardial effusion spontaneously resolves in up to 42% of
patients1,27.
Pericardiocentesis is currently recommended only for large or poorly tolerated
effusions, for diagnostic evaluation of systemic illness or in the presence of
cardiac tamponade1.
Even if the effusion resolves over
time1, these
patients still have excess mortality. The effects of HAART therapy on
pericardial effusion are largely unexplored.
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| ENDOCARDIAL INVOLVEMENT |
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As the autoimmune response to bacterial endocarditis is often largely responsible for associated valvular destruction, HIV-infected patients may have an altered course. For example, HIV-infected patients have a higher risk of developing salmonella endocarditis than immunocompetent patients because they are more likely to develop salmonella bacteraemia during salmonella infection. However, they respond better to antibiotic therapy, and may be less likely to sustain valvular damage because of impaired immune function1.
Non-bacterial thrombotic endocarditis, also known as marantic endocarditis, is most common in patients with HIV wasting syndrome1. It is characterized by friable endocardial vegetations, consisting of platelets within a fibrin mesh with few inflammatory cells. The lesions may involve any of the four valves but are more common on the left side. Systemic or pulmonary embolization can cause serious end-organ damage in spleen, kidneys and myocardium. Systemic embolization from marantic endocarditis is a rare cause of death in AIDS patients1.
| DRUG CARDIOTOXICITY |
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In AIDS patients with Kaposi's sarcoma, reversible cardiac dysfunction was associated with prolonged high-dose therapy with interferon alpha1,34. High-dose interferon alpha treatment is not associated with myocardial dysfunction in other patient populations, so a synergistic effect with HIV infection has been proposed35.
Doxorubicin, used to treat AIDS-related Kaposi's sarcoma and non-Hodgkin lymphoma, has a dose-related effect on dilated cardiomyopathy36, as does foscarnet sodium when used to treat cytomegalovirus oesophagitis37. The prevalence of hypertension associated with erythropoietin therapy is 47%; the effect may be related to the increase in haematocrit and blood viscosity38.
Cardiac arrhythmias (ventricular tachycardia or ventricular fibrillation, torsade de pointes [related to prolongation of QTc interval], atrioventricular conduction abnormalities) have been described with the administration of amphotericin B39, ganciclovir40, co-trimoxazole41 and pentamidine42. Prolongation of QTc interval has been described also with the administration of macrolide antibacterials (erythromycin, clarithromycin)42. In HIV-infected patients cisapride, a prokinetic agent often used for the treatment of gastro-oesophageal reflux, may increase the risk of torsade de pointes when administered in combination with other drugs such as macrolide antibacterials, azole antifungal agents (fluconazole, itraconazole, ketoconazole), all PI (amprenavir, indinavir, nelfinavir, ritonavir, saquinavir), and drugs that have potential additive effects on the QT interval (adenosine, class Ia and III antiarrhythmic drugs)43.
| NUTRITIONAL DEFICIENCIES |
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| CARDIAC INVOLVEMENT IN AIDS-RELATED TUMOURS |
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Malignant lymphoma involving the heart is infrequent in AIDS1,7,46. Lymphomatous infiltration may be diffuse or may result in discrete isolated lesions, which are usually derived from the Burkitt or immunoblastic B cells. The lesions tend to be nodular or polypoid, and they predominantly involve the pericardium, with variable myocardial infiltration1,7. The prognosis of patients with HIV-associated cardiac lymphoma is generally poor, although clinical remission has been observed with combination chemotherapy1.
The better control of human herpes virus 8 and EpsteinBarr virus infection, which are involved in the development of HIV-associated tumours, may account for the reduction, since the advent of HAART, in overall incidence of cardiac involvement by both Kaposi's sarcoma and non-Hodgkin lymphomas.
| CONCLUSIONS |
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| Acknowledgments |
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| REFERENCES |
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and iNOS.
AIDS2000; 14:827
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