Frequency of coronary artery disease and left ventricle dysfunction in cocaine users

Trends of Cocaine Use and Manifestations in Hospitalized Patients: A Cross-Sectional Study

Objective

About 41 million people aged ≥18 years reported lifetime use of cocaine, and 5.4 million people reported having used cocaine in 2019. We aim to identify trends of cocaine use, manifestations, concomitant drug use, and financial burden on health care among hospitalized patients.

Methods

We utilized National Inpatient Sample from years 2006-2018. Patients with age ≥18 years, admitted to the hospital with a diagnosis of cocaine abuse, dependence, poisoning, or unspecified cocaine use were included in the study. We used ICD-9 Clinical Modification (CM) and ICD-10-CM codes to retrieve patient samples and comorbid conditions. The primary outcome was the trend in cocaine use among hospitalized patients from the year 2006 to 2018. Cochran-Mantel-Haenszel test was used to assess the significance of trends.

Results

In the year 2006, the prevalence of cocaine abuse among hospitalized patients was 10,751 per million with an initial decline to 7,451 per million in 2012 and a subsequent increase to 11,891 per million hospitalized patients in 2018 with p =0.01. The majority of patients admitted were older than 50 years (43.27%), and a greater percentage of patients were males. All ethnicities showed a rising trend in the use of cocaine except for Native Americans. Cardiovascular effects, neuropsychiatric and infectious manifestations in hospitalized patients with cocaine abuse showed a consistent increase from year 2006 to 2018 with p <0.001.

Conclusions

There is a recent uptrend in cocaine use among hospital admissions in the US from 2006 to 2018 with an increased rate of systemic manifestations. This highlights the impact of cocaine use on the health system and the dire need to address this growing problem.

Stimulant Drugs of Abuse and Cardiac Arrhythmias

Nonmedical use of prescription and nonprescription drugs is a worldwide epidemic, rapidly growing in magnitude with deaths because of overdose and chronic use. A vast majority of these drugs are stimulants that have various effects on the cardiovascular system including the cardiac rhythm. Drugs, like cocaine and methamphetamine, have measured effects on the conduction system and through several direct and indirect pathways, utilizing multiple second messenger systems, change the structural and electrical substrate of the heart, thereby promoting cardiac dysrhythmias. Substituted amphetamines and cocaine affect the expression and activation kinetics of multiple ion channels and calcium signaling proteins resulting in EKG changes, and atrial and ventricular brady and tachyarrhythmias. Preexisting conditions cause substrate changes in the heart, which decrease the threshold for such drug-induced cardiac arrhythmias. The treatment of cardiac arrhythmias in patients who take drugs of abuse may be specialized and will require an understanding of the unique underlying mechanisms and necessitates a multidisciplinary approach. The use of primary or secondary prevention defibrillators in drug abusers with chronic systolic heart failure is both sensitive and controversial. This review provides a broad overview of cardiac arrhythmias associated with stimulant substance abuse and their management.

Echocardiographic Findings in Heart Failure Patients With Methamphetamine Use: A Case-Control Study

Background

Methamphetamine use is associated with cardiovascular disease and significant morbidity and mortality. There is only one previous study performed on echocardiographic parameters in patients with methamphetamine cardiomyopathy.

Methods

We performed a retrospective review of medical records in a county hospital in Southern California with a high population of methamphetamine users. We reviewed medical records and echocardiogram findings in patients seen in our institution from November 2019 to November 2020 who had cardiomyopathy with and without methamphetamine use. We excluded patients who either left the hospital or expired before appropriate assessment. We divided our patient population into a case group (methamphetamine users) and a control group (non-methamphetamine users) to study and compare their echocardiographic parameters.

Results

Case group included a total of 254 patients and control group included 268 patients. Majority of the patient population were males - 178 (70%) and 180 (67%) in the case and control group respectively. Age was found to be statistically significant with the younger population in the case group (p = 0.0000). Our analysis revealed statistically significant difference in methamphetamine users compared to non-users in regards to left ventricle ejection fraction (33.65% ± 18.02 vs. 41.55% ± 15.61, p=0.0000), left ventricle mass index (122.49 grams/m² ± 40.66 vs. 108.62 grams/m² ± 32.82, p=0.0000), left ventricle end diastolic volume index (85.91 mL/m² ± 37.40 vs. 72.44 mL/m² ± 25.44; p=0.0000) and marginally significant right ventricle systolic pressure (42.29mmHg ± 17.53 vs. 39.59mmHg ± 15.61; p=0.0540)

Conclusion

Our results indicated that methamphetamine users had echocardiogram findings with decreased ejection fraction and increased left ventricular mass index, end-diastolic volume index, and right ventricular systolic pressure consistent with worse dilated cardiomyopathy comparison to non-users.

Drugs of Abuse and Heart Failure

Substance use is common among those with heart failure (HF) and is associated with worse clinical outcomes. Alcohol, tobacco, cannabis, and cocaine are commonly abused substances that can contribute to the development and worsening of HF. Heavy alcohol consumption can lead to dilated cardiomyopathy, whereas moderate intake may decrease incident HF. Tobacco increases the risk of HF through coronary artery disease and coronary artery disease-independent mechanisms. Continued smoking worsens outcomes for those with HF and cessation is associated with an improved risk of major adverse cardiac events. Cannabis has complex interactions on the cardiovascular system depending on the method of consumption, amount consumed, and content of cannabinoids. Delta-9-tetrahydrocannabinol can increase sympathetic tone, cause vascular dysfunction, and may increase the risk of myocardial infarction. Cannabidiol is cardioprotective in preclinical studies and is a potential therapeutic target. Cocaine increases sympathetic tone and is a potent proarrhythmogenic agent. It increases the risk of myocardial infarction and can also lead to a dilated cardiomyopathy. The use of beta-blockers in those with HF and cocaine use is likely safe and effective. Future studies are needed to further elucidate the impact of these substances both on the development of HF and their effects on those who have HF.

Cracking the Opium Den: Cardiothoracic Manifestations of Drug Abuse

Recreational drug use is increasing worldwide, with emergency room visits and total deaths from drug overdose rising in recent years. Complications from prescription and recreational drug use may result from the biochemical effects of the drugs themselves, impurities mixed with substances, or from causes related to the method of drug administration. The presentation of drug overdose may be complex due to multisubstance abuse, including cigarette smoking and alcoholism, and can impact any organ system. Patients may present without history, and radiologists may be the first clinicians to suggest the diagnosis. We aim to explore the cardiothoracic manifestations of drug abuse and their multimodality imaging manifestations.

Cocaine, cardiomyopathy, and heart failure: a systematic review and meta-analysis

Although the cardiotoxic effects of cocaine are universally recognized, the association between cocaine and cardiomyopathy and/or heart failure is poorly understood. To conduct a comprehensive review and meta-analysis on the association between cocaine, heart failure, and cardiomyopathy, we first conducted a broad-term search in PubMed, Embase, Web of Science, and Scopus for human studies containing primary data on the relationship between cocaine and heart failure or cardiomyopathy. We were interested in studies with data beyond acute coronary syndromes. Retrieved studies were grouped into different categories based on possible hypotheses to test by meta-analysis. A second search with specific terms was then conducted. For grouped studies with sufficient clinical and methodological homogeneity, effect sizes were calculated and combined for meta-analysis by the Random Effects model. There is in general a need for more primary data studies that investigate heart failure and/or cardiomyopathy in cocaine users for mechanisms independent of ischemia. There were, however, enough studies to combine by meta-analyses that showed that chronic cocaine use is associated with anatomical and functional changes more consistent with diastolic heart failure instead of the commonly taught dilated cardiomyopathy pathway. In patients without a history of ACS, chronic cocaine use was not associated with significantly reduced EF. The few studies on acute cocaine had conflicting results on whether single-dose intravascular cocaine results in acute heart failure. Studies identified that included beta-blockade therapy in cocaine users with cardiac disease suggest that beta-blockers are not unsafe and that may be effective in the treatment of cocaine-associated heart failure. Chronic cocaine use is associated with anatomical and physiological changes of the heart muscle that are potentially reversible with beta-blockade therapy.

Beta Blocker Therapy in Heart Failure Patients with Active Cocaine Use: A Systematic Review

Background

Cocaine use is associated with multiple cardiovascular complications including heart failure. The use of different types of beta blockers in heart failure patients with active cocaine use is still a matter of debate. In this review, our objective is to systematically review the available literature regarding the use of beta blockers in the treatment of heart failure patients with concurrent cocaine use.

Methods

PubMed, EMBASE, Web of Science, and Clinical Trials.gov were searched from inception to March 2019 using the Medical Subject Headings (MeSH) terms “cocaine”, “heart failure”, “beta blocker,” and “cardiomyopathy”. Only studies containing the outcomes of heart failure patients with active cocaine use who were treated with beta blockers were included.

Results

The search resulted in 2072 articles out of which 12 were finally included in the review. A total number of participants were 1994 with a median sample size of 111. Most of the studies were retrospective in nature with Oxford Centre for Evidence-Based Medicine (OCEBM) Levels of Evidence from 3 to 5. The main primary outcomes included readmission rates, mortality, left ventricular ejection fraction (LVEF) improvement, New York Heart Association (NYHA) functional class, and major adverse cardiovascular events (MACEs). In the studies analyzed, beta blockers were found to have either a beneficial or a neutral effect on primary outcomes in heart failure patients with active cocaine use.

Conclusion

The use of beta blocker therapy appears to be safe and beneficial in heart failure patients with active cocaine use, although the evidence is not robust. Furthermore, large-scale studies are required to confirm this finding.

Cerebrovascular and cardiovascular diseases caused by drugs of abuse

Drugs such as stimulants, sedatives, sleeping pills, and narcotics are associated with drug abuse and are therefore regulated by law. Physical dependence on these drugs is sometimes difficult to control despite an awareness of the problems they cause in daily life and the harm they can cause to the body. Drug dependence is a social problem worldwide, and the physical implications are serious. Many of these drugs cause cerebrovascular and cardiovascular diseases, which often require emergency medical treatment. Differential diagnosis is essential because of the likelihood of life-threatening events, especially among young people who exhibit cerebrovascular and cardiovascular diseases without any of the typical risk factors. Drugs of abuse, especially stimulants, induce a hyperadrenergic state that evokes vasoconstriction and tachycardia, as well as subsequent ischemic and hemorrhagic stroke, acute coronary syndrome, arrhythmias, and aortic dissection. Chronic drug abuse can also cause cardiac hypertrophy and left ventricular dysfunction. As a treatment for these conditions, sedative drugs can be effective but the use of vasodilators may also be required. There are concerns that the use of both alpha- and beta-adrenergic receptor blockers may cause tachycardia and increased blood pressure. Therefore, careful differential diagnosis and selection of therapeutic agents is required.

Dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is a clinical diagnosis characterized by left ventricular or biventricular dilation and impaired contraction that is not explained by abnormal loading conditions (for example, hypertension and valvular heart disease) or coronary artery disease. Mutations in several genes can cause DCM, including genes encoding structural components of the sarcomere and desmosome. Nongenetic forms of DCM can result from different aetiologies, including inflammation of the myocardium due to an infection (mostly viral); exposure to drugs, toxins or allergens; and systemic endocrine or autoimmune diseases. The heterogeneous aetiology and clinical presentation of DCM make a correct and timely diagnosis challenging. Echocardiography and other imaging techniques are required to assess ventricular dysfunction and adverse myocardial remodelling, and immunological and histological analyses of an endomyocardial biopsy sample are indicated when inflammation or infection is suspected. As DCM eventually leads to impaired contractility, standard approaches to prevent or treat heart failure are the first-line treatment for patients with DCM. Cardiac resynchronization therapy and implantable cardioverter-defibrillators may be required to prevent life-threatening arrhythmias. In addition, identifying the probable cause of DCM helps tailor specific therapies to improve prognosis. An improved aetiology-driven personalized approach to clinical care will benefit patients with DCM, as will new diagnostic tools, such as serum biomarkers, that enable early diagnosis and treatment.

The Cardiovascular Effects of Cocaine

Cocaine is the leading cause for drug-abuse-related visits to emergency departments, most of which are due to cardiovascular complaints. Through its diverse pathophysiological mechanisms, cocaine exerts various adverse effects on the cardiovascular system, many times with grave results. Described here are the varied cardiovascular effects of cocaine, areas of controversy, and therapeutic options.

Characteristics, management, and outcomes of cocaine-positive patients with acute coronary syndrome (from the National Cardiovascular Data Registry)

Although cocaine ingestion may cause or contribute to myocardial infarction (MI), few contemporary data are available describing cocaine-associated MI. We describe the characteristics, management, and outcomes of patients with MI and recent cocaine use from the Acute Coronary Treatment and Intervention Outcomes Network Registry-Get With The Guidelines (ACTION Registry-GWTG) program. The study population was 102,952 patients enrolled in the American College of Cardiology ACTION Registry-GWTG from July 2008 to March 31, 2010 from 460 sites across the United States. Cocaine exposure was defined as self-reported cocaine use within the last 72 hours or a positive urine test for cocaine. Demographics and medical history, presenting characteristics, treatments, and in-hospital outcomes were reported on a standard case record form. A total of 924 patients (0.9%) were cocaine positive. Compared with cocaine-negative patients, cocaine-positive patients were younger and predominantly men with fewer cardiovascular risk factors. There was a higher percentage of ST elevation myocardial infarction (STEMI) (46.3% vs 39.7%) and cardiogenic shock at presentation in the cocaine-positive group, but the percentage of multivessel coronary artery disease was lower (53.3% vs 64.5%). Beta blockers within 24 hours (85.8% vs 90.1%, p <0.0001) and drug-eluting stents (40.1% vs 68.8%, p <0.0001 in patients with non-STEMI; 27.6% vs 54.6%, p <0.0001 in patients with STEMI) were used less commonly in cocaine-positive patients. Multivariable-adjusted in-hospital mortality was similar between cocaine-positive and cocaine-negative patients (adjusted odds ratio 1.00, 95% confidence interval 0.69 to 1.44, p value = 0.98). In conclusion cocaine-positive patients with acute coronary syndrome are younger with fewer risk factors, multivessel coronary artery disease and lower drug-eluting stent and β-blocker usage. Cocaine use was not associated with in-hospital mortality.

A review on renal toxicity profile of common abusive drugs

Drug abuse has become a major social problem of the modern world and majority of these abusive drugs or their metabolites are excreted through the kidneys and, thus, the renal complications of these drugs are very common. Morphine, heroin, cocaine, nicotine and alcohol are the most commonly abused drugs, and their use is associated with various types of renal toxicity. The renal complications include a wide range of glomerular, interstitial and vascular diseases leading to acute or chronic renal failure. The present review discusses the renal toxicity profile and possible mechanisms of commonly abused drugs including morphine, heroin, cocaine, nicotine, caffeine and alcohol.

Is cocaine use recognised as a risk factor for acute coronary syndrome by doctors in the UK?

BACKGROUND

Cocaine is a sympathomimetic agent that can cause coronary artery vasospasm leading to myocardial ischaemia, acute coronary syndrome and acute myocardial infarction (ACS/AMI). The management of cocaine-induced ACS/AMI is different to classical atheromatous ACS/MI, because the mechanisms are different.

METHODS

Knowledge study--Junior medical staff were given a scenario of a patient with ACS and asked to identify potential risk factors for ACS and which ones they routinely asked about in clinical practice. Retrospective study--Retrospective notes reviews of patients with suspected and proven (elevated troponin T concentration) ACS were undertaken to determine the recording of cocaine use/non-use in clinical notes.

RESULTS

Knowledge study--There was no significant difference in the knowledge that cocaine was a risk factor compared to other "classical" cardiovascular risk factors, but juniors doctors were less likely to ask routinely about cocaine use compared to other "classical" risk factors (52.9% vs >90%, respectively). Retrospective study--Cocaine use or non-use was documented in 3.7% (4/109) and 4% (2/50) of clinical notes of patients with suspected and proven ACS, respectively.

DISCUSSION

Although junior medical staff are aware that cocaine is a risk factor for ACS/AMI, they are less likely to ask about it in routine clinical practice or record its use/non-use in clinical notes. It is essential that patients presenting with suspected ACS are asked about cocaine use, since the management of these patients is different to those with ACS secondary to "classical" cardiovascular risk factors.

Chronic nephropathies of cocaine and heroin abuse: a critical review

Renal disease in cocaine and heroin users is associated with the nephrotic syndrome, acute glomerulonephritis, amyloidosis, interstitial nephritis, and rhabdomyolysis. The pathophysiologic basis of cocaine-related renal injury involves renal hemodynamic changes, glomerular matrix synthesis and degradation, and oxidative stress and induction of renal atherogenesis. Heroin is the most commonly abused opiate in the United States. Previous studies identified a spectrum of renal diseases in heroin users. The predominant renal lesion in black heroin users is focal segmental glomerulosclerosis and in white heroin users is membranoproliferative glomerulonephritis. Although the prevalence of heroin use in the United States has increased, the incidence of "heroin nephropathy" has declined. Because reports of heroin nephropathy predated the surveillance of hepatitis C virus and HIV, the varied findings might be related to the spectrum of viral illnesses that are encountered in injection drug users. Socioeconomic conditions, cultural and behavioral practices, or differences in genetic susceptibilities may be more associated with the development of nephropathy in heroin users than the drug's pharmacologic properties. Administration of cocaine in animal models results in nonspecific glomerular, interstitial, and tubular cell lesions, but there is no animal model of heroin-associated renal disease. The heterogeneity of responses that are associated with heroin is not consistent with a single or simple notion of nephropathogenesis. There are no well-designed, prospective, epidemiologic studies to assess the incidence and the prevalence of renal disease in populations of opiate users and to establish the validity of a syndrome such as heroin nephropathy. It is concluded although there is a paucity of evidence to support a heroin-associated nephropathy, the evidence from in vitro cellular and animal studies to support the existence of cocaine-induced renal changes is more convincing.

Evaluation and Management of the Patient Who Has Cocaine-associated Chest Pain

Patients who have chest pain following the use of cocaine have become more common in emergency departments throughout the United States,with approximately 6% of these patients sustaining an acute MI. The authors have described the rationale for recommending aspirin, benzodiaze-pines, and nitroglycerin as first-line treatments and calcium-channel blockade or phentolamine as possible second-line therapies and have summarized the controversies surrounding the use of fibrinolytic agents. Admission for observation is one reasonable approach to the management of the low-risk cohort. Evaluation for underlying coronary artery disease is reasonable, particularly in patients who have acute MI. Patients who do not have infarction can undergo evaluation for possible coronary artery disease on an outpatient basis. Routine interventions for secondary prophylaxis as well as cocaine rehabilitation should be used in this patient population, because the long-term prognosis seems somewhat dependent upon the ability of the patient to discontinue cocaine use.

Intravascular ultrasound-guided percutaneous coronary intervention in a human immunodeficiency virus-positive patient with cocaine-associated acute myocardial infarction: case report and review

Cocaine use is a major problem worldwide and there are numerous reports about cocaine-associated myocardial infarction. Nevertheless minimal data are available from randomised clinical trials to suggest evidence-based approaches to the management of cocaine-associated myocardial ischemia. Moreover, most reports have been limited to conservative management of cocaine-associated myocardial infarction. We report a case of a young male cocaine user with acute myocardial infarction, undergoing diagnostic coronary angiography and intravascular ultrasound revealing severe atherosclerosis, followed by successful stent implantation.

Cocaine and coronary calcification in young adults: the Coronary Artery Risk Development in Young Adults (CARDIA) Study

BACKGROUND

Cocaine use is associated with myocardial ischemia and infarction, but it is unclear whether this is only because of the acute effects of cocaine on heart rate, blood pressure, and vasomotor tone or whether accelerated atherosclerosis from long-term exposure to cocaine also contributes.

METHODS

We sought to measure the association between cocaine exposure and coronary calcification, a marker for atherosclerosis, among participants in the CARDIA Study who received computed tomography scanning and answered questions about illicit drug use at the year 15 examination in 2000-2001.

RESULTS

Among 3038 CARDIA participants (age 33-45 years, 55% women and 45% black), past cocaine exposure was reported by 35% and was more common among men, smokers, drinkers, and participants with less education. Powdered cocaine exposure was more common among whites, crack cocaine among blacks. Before adjustment, cocaine exposure was strongly associated with coronary calcification. After adjusting for age, sex, ethnicity, socioeconomic status, family history, and habits, however, these associations disappeared: adjusted odds ratios for coronary calcification were 0.9 (95% CI 0.6-1.3) for 1 to 10, 1.2 (95% CI 0.8-1.7) for 11 to 99, and 1.0 (95% CI 0.6-1.6) for > or =100 lifetime episodes of cocaine use, in comparison with none. Sex, tobacco, and alcohol use appeared to be primarily responsible for the confounding we observed in unadjusted models.

CONCLUSION

We found no evidence of a causal relationship between long-term exposure to cocaine and coronary calcification and conclude that acute nonatherogenic mechanisms probably explain most cocaine-associated myocardial infarction.

Effects of cocaine and caffeine alone and in combination on cardiovascular performance

BACKGROUND

With the proliferation of cocaine abuse, increased incidence of catastrophic cardiovascular events like angina pectoris, myocardial infarction, ventricular arrhythmias or sudden death are reported. Cocaine-dependent subjects commonly abuse multiple substances. Many of them drink coffee before and after cocaine use. The high frequency of simultaneous exposure to both the drugs may influence outcome of the cocaine's treatment. Cocaine and caffeine's independent effects on cardiodynamics are documented but to our knowledge combined effects of both on complete cardiovascular hemodynamics remains to be examined.

METHODS

Eighteen dogs were instrumented to pass cardiac catheters into right and left heart. The experiments were performed after they recovered from the effects of anesthesia. In phase I (30 experiments on 8 dogs), the doses were established by dose-response curve. In phases II and III, another 10 dogs were subjected to 28 experiments. They were given i.v. cocaine followed by caffeine and vice versa to study their effects on hemodynamics and coronary flow reserve.

RESULTS

Phase 1: The doses of cocaine (2 mg/kg) and caffeine (5 mg/kg) were established. Phase II: Cocaine increased heart rate, blood pressure and dP/dt but CFR decreased significantly. Caffeine administered after cocaine attenuated these effects (dP/dt decreased to 4910+/-104 from 5066+/-110 mm Hg s; p<NS). Phase III: Caffeine mildly increased hemodynamic parameters but reduced dP/dt. Cocaine's administration as the second drug had synergistic excitatory effects (dP/dt increased to 6166+/-160 from 5055+/-142 mm Hg/s; p<0.04). CFR decreased significantly.

CONCLUSION

Cocaine increased heart rate, blood pressure and dP/dt but reduced CFR. Caffeine mildly increased the hemodynamic variables but decreased CFR. Combined cocaine+caffeine attenuated the excitatory effects of cocaine significantly. A reversed drug combination i.e., caffeine+cocaine generated synergistic excitatory effects on the cardiovascular system of the dogs. CFR showed significant decrease.

Effect of acute intravenous cocaine administration on endothelium-dependent vasodepressor responses to acetylcholine

BACKGROUND

Cardiovascular events commonly associated with acute and chronic cocaine abuse include coronary vasospasm, arrhythmias, myocardial infarction, and sudden death. It has been suggested that cocaine causes endothelial dysfunction and vasoconstriction by inhibiting local production of nitric oxide and that endothelial dysfunction may be involved in the cardiovascular events associated with cocaine use. The present study investigated the effect of acute intravenous cocaine administration on endothelium-dependent vasodepressor responses to acetylcholine in the anesthetized rat.

METHODS AND RESULTS

Rats were anesthetized with intraperitoneally Inactin (140 mg/kg) and catheters were inserted into the jugular vein and iliac artery for the injection of drugs and measurement of systemic arterial pressure. A thermistor catheter was advanced to the aortic arch for the measurement of cardiac output via the thermal dilution technique. A 5 mg/kg intravenous dose of cocaine, which enhances the vasopressor response to norepinephrine and blocks the vasopressor response to tyramine, had no effect on the vasodepressor response to the endothelium-dependent vasodilator acetylcholine. In addition, responses to the nitric oxide-donor sodium nitroprusside and the vasoconstrictor peptide angiotensin II were not altered by administration of cocaine.

CONCLUSIONS

Acute administration of cocaine in a dose that blocks norepinephrine uptake into adrenergic terminals had no effect on endothelial function as measured by the absence of an effect on the vasodepressor response to intravenous injections of acetylcholine. Although chronic cocaine exposure has been shown to cause vascular dysfunction, eventually leading to impairment of the nitric oxide pathway, it appears that acute cocaine administration does not inhibit this pathway in the anesthetized rat.

Cardiovascular disorders associated with cocaine use: myths and truths

Cocaine produces a pattern of cardiovascular responses that are associated with apparent myocardial ischemia, arrhythmias, and other life-threatening complications in some individuals. Despite recent efforts to better understand the causes of cocaine-induced cardiovascular dysfunction, there remain a number of unanswered questions regarding the specific mechanisms by which cocaine elicits hemodynamic responses. This review will describe the actions of cocaine on the cardiovascular system and the evidence for the mechanisms by which cocaine elicits hemodynamic and pathologic responses in humans and animals. The emphasis will be on experimental data that provide the basis for our understanding of the mechanisms of cardiovascular toxicity associated with cocaine. More importantly, this review will identify several controversies regarding the causes of cocaine-induced cardiovascular toxicity that as yet are still debated. The evidence supporting these findings will be described. Finally, this review will outline the obvious deficits in our current concepts regarding the cardiovascular actions of cocaine in hope of encouraging additional studies on this grave problem in our society.

Coronary angiographic findings in patients with cocaine-associated chest pain

Patients who present to the Emergency Department (ED) with chest pain associated with cocaine use are a common problem. The incidence and predictors of underlying significant coronary disease in patients with and without myocardial infarction (MI) has not been well described. Patients who underwent coronary angiography within 5 weeks of an ED evaluation for cocaine-associated chest pain were studied. Significant disease was defined as > or = 50% stenosis of a coronary artery or major branches or bypass graft. A total of 90 patients underwent coronary angiography. Significant disease was present in 45 (50%), with 1-vessel disease in 32%, 2-vessel disease in 10%, 3-vessel disease in 6%, with significant graft stenosis in 3%. Significant disease was present in 77% of patients with MI or troponin I elevations, compared to only 35% of patients without myonecrosis. Predictors of significant coronary disease included MI or troponin I elevations, prior MI, known coronary disease (prior MI or revascularization), and elevated cholesterol. Only 7 of the 39 patients (18%) without myonecrosis or a history of coronary disease had significant disease on angiography. In conclusion, significant disease is found in the majority of patients with cocaine-associated MI or troponin elevations. In contrast, only a minority of those without myonecrosis have significant coronary disease.

Effects of cocaine and alcohol alone and in combination on cardiovascular performance in dogs

BACKGROUND

With the proliferation of cocaine abuse, increased incidence of catastrophic cardiovascular events such as angina pectoris, myocardial infarction, ventricular arrhythmias, or sudden death are reported. Many of these patients also drink alcohol before and after cocaine use, leading to a high frequency of simultaneous exposure to both the drugs. Cocaine and ethanol's independent effects on cardiodynamics are well documented, but their combined effects on complete cardiovascular hemodynamics remain unknown. Are effects additive, synergistic, or antagonistic?

METHODS

Sixteen dogs were instrumented to pass cardiac catheters into right and left ventricles. After they recovered from the effects of anesthesia, experiments were performed. In phase I, 18 experiments (6 dogs) established the dose by dose response curve. In phase II and III, another 10 dogs, subjected to 30 experiments, were given i.v. cocaine followed by ethanol and vice versa to study their effects on hemodynamics and coronary flow reserve.

RESULTS

Phase I: doses of cocaine (2 mg/kg) and ethanol (400 mg/kg) were established. Phase II: cocaine increased heart rate, blood pressure and dP/dt but ethanol administered after cocaine attenuated these effects [first derivative of the left ventricular pressure (dP/dt) < 2052 +/- 104 from 2614 +/- 110 mm Hg/sec; P < 0.04)]. Phase III: alcohol mildly increased hemodynamic parameters. Cocaine's administration as the second drug had synergistic excitatory effects (dP/dt > 3300 +/- 160 from 2854 +/- 142 mm Hg/sec; P < 0.004).

CONCLUSION

Cocaine increased heart rate, blood pressure, and dP/dt but reduced CFR. Alcohol mildly increased the hemodynamic variables and CFR. Combined cocaine and alcohol attenuated the excitatory effects of cocaine significantly. A reversed drug combination (ie, alcohol then cocaine) generated synergistic excitatory effects on the cardiovascular system of the dogs.

Percutaneous interventions in patients with cocaine-associated myocardial infarction: a case series and review

Cocaine-associated myocardial infarction (CAMI) is a well-reported entity. Most previous reports on CAMI have been limited to conservative care utilizing benzodiazepines, aspirin, nitroglycerin, calcium channel blockers, and thrombolytics. Current guidelines on CAMI advocate immediate use of angiography and angioplasty if available rather than routine administration of thrombolytics. However, based on literature search from 1966 to 2001 (using keywords "cocaine," "myocardial infarction," and "angioplasty"), there have been only two case reports of percutaneous coronary intervention (PCI) in patients with cocaine-associated myocardial infarction. Both were notable for complications either during or immediately after the procedure. We report a series of 10 patients with cocaine-associated myocardial infarction who were treated with percutaneous interventions, which included angioplasty, stenting, and AngioJet mechanical extraction of thrombus. Despite the different arteriopathic process involved, our findings suggest that PCI can be performed safely and with a high degree of procedural success in patients with CAMI.

Myocardial infarction in young adults with low-density lipoprotein cholesterol levels < or = 100 mg/dL: clinical profile and 1-year outcomes

STUDY OBJECTIVES

To define the clinical profile of young adults with optimal low-density lipoprotein (LDL) cholesterol levels who present with acute myocardial infarctions (MIs); to compare and contrast differences in the clinical profiles of young adults admitted to the hospital with MIs who have LDL cholesterol levels < or = 100 mg/dL and those with LDL cholesterol values > or = 160 mg/dL; and to evaluate the clinical outcomes for the two groups at 1 year.

DESIGN

A retrospective chart review was conducted on all young men (55 years) and women (65 years) admitted to the hospital for MIs within a 2-year period (n = 232). A history of cardiovascular risk factors and 1-year outcomes were obtained.

SETTING

Rural community medical center serving a tri-state area in the midwestern United States.

PATIENTS

Patients were included in this analysis if (1) a lipid profile was drawn within 24 h of hospital admission and (2) the patient was not receiving a statin medication on hospital admission.

MEASUREMENTS AND RESULTS

Of the 183 patients who met the inclusion criteria, as many as 68% (124 patients) had LDL cholesterol levels of < or = 130 mg/dL, 29% (53 patients) had LDL cholesterol level of < or = 100 mg/dL, and only 14% (26 patients) had LDL cholesterol levels of > or = 160 mg/dL. Patients were categorized into group 1 if their LDL cholesterol level was < or = 100 mg/dL and were categorized into group 2 if their LDL cholesterol level was > or = 160 mg/dL. In group 2, 92% of patients were placed on a statin medication. By 1 year, the mean LDL cholesterol level had decreased from 188 to 106 mg/dL. The rate of coronary artery bypass graft and percutaneous coronary intervention procedures was similar between groups. Hospital readmission rates (43.4% vs 50%, respectively) and 1-year mortality rates (9% vs 8%, respectively) were not different between groups group 1 and 2.

CONCLUSIONS

Young adults experiencing acute MIs typically have acceptable cholesterol levels (ie, < or = 130 mg/dL) or optimal values (ie, < or = 100 mg/dL). In those patients with abnormal cholesterol levels, a combined strategy of aggressive intervention and adherence to secondary prevention protocols including lipid control is successful in improving outcomes.

Effects of cocaine on the coronary arteries

BACKGROUND

A number of studies have documented myocardial ischemia and infarction associated with cocaine use. Mismatch between myocardial oxygen supply and demand from cocaine-induced vasoconstriction and increased myocardial workload are often invoked as the major postulated mechanism by which cocaine induces myocardial ischemia. This article reviews the literature studying the effects produced by cocaine on the coronary arteries to provide insight into the various pathophysiologic mechanisms by which cocaine triggers acute cardiac ischemia or infarction.

METHODS

We reviewed the published literature describing the effects of cocaine on the coronary arteries. A MEDLINE search of English language articles published between 1985 and 2000 was performed. Key words included coronary arteries, coronary vasoconstriction, vasospasm, coronary vasodilation, cardiac vasculature, myocardial ischemia, platelets, thrombosis, and cocaine. Both animal and human studies were included. The bibliographies of identified articles were also explored for additional sources of information.

RESULTS

A recreational dose of cocaine increases the heart rate by approximately 30 beats/min. It also increases the blood pressure by 20/10 mm Hg. These increases are modest, are equivalent to mild exercise, and are not believed to be sufficient to result in myocardial ischemia in the majority of cases. Animal and human studies have documented cocaine-induced early coronary artery vasodilation as shown by a decrease in coronary perfusion pressure ranging from 13% to 68%. This was followed by a more sustained vasoconstriction demonstrated by a decrease in epicardial coronary artery diameter ranging from 5% to 30% with various doses of cocaine by various methods of administration. These changes alone are also an unlikely explanation for cocaine-induced myocardial ischemia. Therefore neither increases in myocardial workload nor hemodynamic changes are sufficient to explain cocaine-induced myocardial ischemia. However, evidence also exists that cocaine activates platelets and promotes thrombosis, resulting in intracoronary thrombus formation. Cocaine may also promote premature and more severe coronary atherosclerosis.

CONCLUSION

The etiology of cocaine-induced myocardial ischemia is complex and is likely to be multifactorial. It appears to be the result of coronary artery vasoconstriction, intracoronary thrombosis, and accelerated atherosclerosis.

Neurobiological adaptations to psychostimulants and opiates as a basis of treatment development

Abuse of illicit substances, in particular psychostimulants and opiates, is a worldwide public health issue. Chronic use of cocaine and amphetamine causes common neurobiological adaptations that may guide new treatment development. These include perturbations in dopamine and serotonin neurotransmission, leading to trials of antidepressants, and serotonin and dopamine augmentation strategies. The detection of cerebral perfusion abnormalities caused by psychostimulants has led to examination of antiplatelet and excitatory amino acid (EAA) antagonist therapies. Further, development of cocaine vaccines allows for testing of peripheral blockade approaches to cocaine addiction. New approaches to behavioral treatments for cocaine dependence are also reviewed. For opiate dependence, understanding of heroin's effects on mu and kappa opiate receptors has led to investigations of the partial mu agonist buprenorphine in opiate maintenance. Evidence for hyper-excitability of locus coeruleus (LC) noradrenergic neurons and EEA inputs to the LC guides trials of new alpha 2-adrenergic agonists and EEA antagonists to alleviate opiate withdrawal. Finally, clinical experience with withdrawal from methadone and LAAM has led to trials of antagonist-accelerated opiate withdrawal. Improved treatment of psychostimulant and opiate addiction is critically needed, and likely to have wide-reaching impact in health care and society.

Cocaine and the kidney: a synthesis of pathophysiologic and clinical perspectives

Cocaine abuse has reached epidemic proportions in the United States, and several forms of renal disease have been associated with this widespread use. The hemodynamic actions of cocaine, as well as its effects on matrix synthesis, glomerular inflammation, and glomerulosclerosis, may contribute to renal injury. Cocaine abuse has been associated with various forms of acute renal failure and acid-base and/or electrolyte disorders and may also have a role in the progression of chronic renal failure to end-stage renal disease. In utero exposure to cocaine has been associated with urogenital tract anomalies. Medical management of a hypertensive emergency caused by acute cocaine toxicity requires a multisystem approach, with close monitoring of cardiac, neurological, and renal functions.

Mild hypercholesterolemia and premature heart disease: do the national criteria underestimate disease risk?

OBJECTIVES

To determine the frequency of hospital admissions for acute coronary syndrome in young adults and to examine the risk factors that predispose to the development of premature heart disease.

BACKGROUND

Significant coronary heart disease (CHD) is considered rare in the young adult. Current guidelines do not recommend treatment of mild cholesterol abnormalities for primary prevention of CHD in the young.

METHODS

This is a large case series of 449 adults (< or =50 years) admitted to the hospital with acute coronary syndrome. A history of cardiovascular risk factors and lipid profile were recorded. The presence and extent of CHD were established.

RESULTS

Mean patient age was 44 +/- 6 years. Documented CHD was present in 61% of hospital admissions. Multivariate analysis revealed that history of hypercholesterolemia, history of smoking and diabetes were independently associated with premature CHD. The fasting lipid profiles were only borderline to mildly abnormal. Serum total cholesterol, low-density lipoprotein (LDL) and triglyceride levels were not different in cases compared with control subjects. Nearly half (49%) of those with LDL levels of > or =160 mg/dl had only one additional risk factor or none. Despite this, a history of hypercholesterolemia had independent and incremental value on other risk factors for the likelihood of premature CHD.

CONCLUSIONS

The magnitude of hospital admissions relating to premature CHD is high. In this population, the presence of borderline or mild hypercholesterolemia has significant effects on the development of premature CHD. These observations have significant implications in the development of guidelines for primary prevention of premature CHD.

Percutaneous transluminal coronary angioplasty and stenting for cocaine-induced acute myocardial infarction: a case report and review

Cocaine-induced myocardial infarction has been well reported. Likewise, there are numerous reports of patients with cocaine-induced myocardial infarction being treated conservatively with nitroglycerin, verapamil, and thrombolytics. However, based on a Medline search from 1977 to 1998 (with the keywords cocaine and angioplasty), there have been no reports in English of cocaine-induced myocardial infarction being treated with catheter-based intervention. We report such a case, as well as review what is known about the pathophysiology of cocaine-induced coronary arteriopathy and myocardial infarction.

Concurrent use of cocaine and alcohol is more potent and potentially more toxic than use of either alone--a multiple-dose study

BACKGROUND

Simultaneous abuse of cocaine and alcohol is widespread and increasingly detected in patients seeking emergent care. This double-blind, randomized, within-subjects study used a paradigm more closely approximating practices of drug abusers to better understand the pathogenesis of cocaine-alcohol abuse.

METHODS

Subjects meeting DSM-IV criteria for cocaine dependence and alcohol abuse participated in three drug administration sessions: four doses of intranasal cocaine (1 mg/kg every 30 min) with oral alcohol (1 g/kg) administered following the initial cocaine dose and a second dose (120 mg/kg) at 60 min calculated to maintain plasma alcohol concentration at approximately 100 mg/dL during cocaine administration; four doses of cocaine/placebo alcohol; four doses of cocaine placebo/alcohol. Pharmacokinetic, physiological, and behavioral effects were followed over 8 hours.

RESULTS

Cocaine-alcohol produced greater euphoria and increased perception of well-being relative to cocaine. Heart rate significantly increased following cocaine-alcohol administration relative to either drug alone. Cocaine concentrations were greater following cocaine-alcohol administration. Cocaethylene had a longer halflife with increasing concentrations relative to cocaine at later time points.

CONCLUSIONS

Enhanced psychological effects during cocaine-alcohol abuse may encourage ingestion of larger amounts of these substances over time placing users at heightened risk for greater toxicity than with either drug alone.

Cocaine increases the endothelial release of immunoreactive endothelin and its concentrations in human plasma and urine: reversal by coincubation with sigma-receptor antagonists

BACKGROUND

Cocaine-associated vascular events are not completely explained by adrenergic stimulation. The purposes of this study were to investigate whether vasoconstrictive endothelin-1 is released by cocaine and to elucidate the mechanisms involved.

METHODS AND RESULTS

Endothelin-1 was measured by radioimmunoassay and high-performance liquid chromatography (1) in the supernatant of porcine aortic endothelial cells after treatment with cocaine (10(-7) to 10(-4) mol/L) and a sigma-receptor antagonist, haloperidol (10(-6) mol/L) or ditolylguanidine (10(-5) mol/L) and (2) in plasma and urine of 12 cocaine-intoxicated patients and 13 healthy control subjects. Radioligand binding assays were performed on endothelial membrane preparations. In cell culture, cocaine significantly increased endothelin accumulation above baseline at 3 to 24 hours; endothelin release rates per hour increased dose-dependently, reaching a plateau of 175+/-23% of control at hour 4 to 5. Coincubation of cocaine with haloperidol or ditolylguanidine abolished or reduced cocaine-induced endothelin release. Endothelial membrane preparations specifically and displaceably bound the highly selective sigma-ligand [3H]ditolylguanidine (25x10(-9) mol/L), with 1400 binding sites estimated per cell. Endothelin-1 levels in plasma (22.7+/-5.6 versus 7.3+/-0.8 pmol/L) and urine (41.5+/-10.1 versus 12.7+/-3.8 pmol/L) of cocaine-intoxicated patients were significantly increased compared with control values.

CONCLUSIONS

The data suggest that cocaine increases the endothelin-1 release in vitro and in vivo. The cocaine-induced vasoconstriction/vasospasm may therefore be facilitated by the release of endothelin-1. Cocaine appears to be an exogenous stimulator at endothelial sigma-receptors. The endogenous ligands of this antiopioid system may prove to play a role in vasospastic angina, acute myocardial infarction, and sudden cardiac death.

Evidence for a serotonin-mediated effect of cocaine causing vasoconstriction and herniated umbilici in chicken embryos

Some of cocaine (COC)'s pathophysiological effects on exposed embryos likely result from its vasoconstrictive action, and serotonin2 (5-HT2) agonists such as dimethoxyiodophenylaminopropane (DOI) can mimic these effects. Infusions of COC (5 mg/kg/min) or DOI (0.5 mg/kg/min) for 15 min into chicken eggs with embryos on E15 caused a significant reduction in blood vessel diameters (14 and 30%, respectively). Pretreatment with the 5-HT2 antagonist ritanserin (RIT, 0.9 mg/kg) 18-22 h earlier blocked the effect of COC and blocked or attenuated the effect of DOI. In separate groups of chicken embryos exposed to multiple injections of low doses of COC on E18, herniated umbilici were prominent in hatchlings. A single bolus injection of the same absolute amount of COC did not cause herniated umbilici. An additional experiment replicated the induction of herniated umbilici by multiple injections of COC and demonstrated the probable involvement of 5-HT2 receptors because RIT blocked COC's ability to induce this anomaly. These data suggest that COC's vasoconstrictive effect, via 5-HT2 receptors, may play a mechanistic role in some adverse outcomes in embryos exposed to COC.

Pharmacotherapy of cerebral ischemia in cocaine dependence

This paper will examine how cerebral perfusion deficits in cocaine abusers may be a target for pharmacotherapy. The review covers five areas: (1) cerebral ischemia and neuropsychological impairment in cocaine abusers, (2) neuroimaging evidence for cerebral perfusion defects in cocaine abusers, (3) mechanisms for cocaine induced cerebral thrombosis, (4) neurotoxicity from cerebral ischemia and excitatory amino acids, (5) glutamate antagonists as potential treatment agents for cocaine induced neurotoxicity. Several pharmacotherapies are suggested including antiplatelet agents and excitatory amino acid (EAA) antagonists such as lamotrigine. Clinical trials in cocaine abusers with cerebral perfusion defects are indicated and EAA antagonists hold promise as they are developed for stroke treatment.

Evaluation of chest pain in the emergency department

The evaluation of chest pain in the emergency setting should be systematic, risk based, and goal driven. An effective program must be able to evaluate all patients with equal thoroughness under the assumption that any patient with chest pain could potentially be having an MI. The initial evaluation is based on the history, a focused physical examination, and the ECG. This information is sufficient to categorize patients into groups at high, moderate, and low risk. Table 14 is a template for a comprehensive chest-pain evaluation program. Patients at high risk need rapid initiation of appropriate therapy: thrombolytics or primary angioplasty for the patients with MIs or aspirin/heparin for the patients with unstable angina. Patients at moderate risk need to have an acute coronary syndrome ruled in or out expediently and additional comorbidities addressed before discharge. Patients at low risk also need to be evaluated, and once the likelihood of an unstable acute coronary syndrome is eliminated, they can be discharged with further evaluation performed as outpatients. Subsequent evaluation should attempt to assign a definitive diagnosis while also addressing issues specific to risk reduction, such as cholesterol lowering and smoking cessation. It is well documented that 4% to 5% of patients with MIs are inadvertently missed during the initial evaluation. This number is surprisingly consistent among many studies using various protocols and suggests that an initial evaluation limited to the history, physical examination, and ECG will fail to identify the small number of these patients who otherwise appear at low risk. The solution is to improve the sensitivity of the evaluation process to identify these patients. It appears that more than simple observation is required, and at the present time, no simple laboratory test can meet this need. However, success has been reported with a number of strategies including emergency imaging with either radionuclides such as sestamibi or echocardiography. Early provocative testing, either stress or pharmaceutic, may also be effective. The added value of these tests is only in their use as part of a systematic protocol for the evaluation of all patients with acute chest pain. The initial evaluation of the patient with chest pain should always consider cardiac ischemia as the cause, even in those with more atypical symptoms in whom a cardiac origin is considered less likely. The explicit goals for the evaluation of acute chest pain should be to reduce the time to treat MIs and to reduce the inadvertent discharge of patients with occult acute coronary syndromes. All physicians should become familiar with appropriate risk stratification of patients with acute chest pain. Systematic strategies must be in place to assure rapid and consistent identification of all patients and the expedient initiation of treatment for those patients with acute coronary syndromes. These strategies should include additional methods of identifying acute coronary syndromes in patients initially appearing as at moderate or low risk to assure that no unstable patients are discharged. All patients should be followed up closely until the cardiovascular evaluation is completed and, when possible, a definitive diagnosis is determined. Finally, this must be done efficiently, cost-effectively, and in a manner that will result in an overall improvement in patient care.

Endothelium-dependent vasorelaxation is impaired in cocaine arteriopathy

OBJECTIVES

This study sought to assess endothelium-dependent vasorelaxation in long-term users of cocaine.

BACKGROUND

Cocaine use has been associated with myocardial infarction, stroke and intestinal infarction. Previously demonstrated effects of the drug, including increased heart rate and blood pressure and increased vascular tone, do not explain the sporadic nature of these vascular events or the occurrence of ischemia remote from acute administration. Abnormal endothelial function could contribute to focal vasospasm and thrombosis and predispose to premature atherosclerosis, all of which have been demonstrated in cocaine users with myocardial infarction.

METHODS

Using plethysmography, we studied the change in forearm blood flow in response to intraarterial acetylcholine and nitroprusside in 10 long-term cocaine users and 13 control subjects of similar age who had not used cocaine; sample size was based on a 70% power to detect a 20% reduction in flow with acetylcholine between subjects and control subjects. Using graded doses of intracoronary acetylcholine (from 10(-9) to 10(-6) mol/liter), we studied a second group of 10 cocaine users with angiographically normal or near-normal arteries.

RESULTS

Mean forearm blood flow during acetylcholine infusion was significantly lower in cocaine users than in control subjects (p = 0.02). During nitroprusside infusion, there was no difference (p = 0.2) between cocaine users and control subjects. Cigarette smoking did not explain the differences between cocaine users and control subjects. Acetylcholine elicited coronary vasoconstriction in 8 of 10 subjects.

CONCLUSIONS

We conclude that endothelium-dependent vasorelaxation is impaired in long-term users of cocaine.

Effect of cocaine on left ventricular function. Relation to increased wall stress and persistence after treatment

BACKGROUND

To determine whether alterations in left ventricular (LV) function after a cocaine infusion are due to reduced myocardial contractility or changes in loading conditions, we examined LV function in 30 morphine-sedated, closed-chest dogs. We also wanted to determine the time course of the effects of cocaine on LV function after the infusion was stopped.

METHODS AND RESULTS

Two-dimensional echocardiography and hemodynamics provided LV fractional shortening and end-systolic wall stress data. Radionuclide ventriculography was also performed. Four groups of dogs received saline or cocaine infusions of 10, 30, or 100 micrograms.kg-1.min-1. Cocaine was infused for 90 minutes with ECG and arterial pressure monitoring. Animals were monitored for an additional 120 minutes after the infusion ended. Arterial pressure rose over the course of the experiment in all four groups, but saline and cocaine 10 micrograms.kg-1.min-1 did not significantly change ejection fraction. Cocaine 30 and 100 micrograms.kg-1.min-1 acutely increased arterial pressure and heart rate but decreased ejection fraction from 0.64 +/- 0.06 to 0.45 +/- 0.08 and from 0.65 +/- 0.10 to 0.46 +/- 0.11, respectively. Additionally, cocaine 100 micrograms.kg-1.min-1 decreased fractional shortening from 36 +/- 9% to 23 +/- 12%. However, cocaine 30 and 100 micrograms.kg-1.min-1 also increased wall stress from 42 +/- 15 to 65 +/- 11 g/cm2 and from 37 +/- 15 to 90 +/- 33 g/cm2, respectively. These results were analyzed by use of the relation between wall stress and fractional shortening as an index of contractility. Fractional shortening after cocaine infusion was displaced downward as a result of increased wall stress rather than changes in contractility. In addition, alteration of afterload with phenylephrine (6 micrograms/kg) and sodium nitroprusside (10 micrograms/kg) before and during infusion of cocaine 100 micrograms.kg-1.min-1 showed similar regression lines for wall stress to fractional shortening.

CONCLUSIONS

Ejection-phase indexes of LV function were reduced by cocaine in this model of conscious, sedated dogs, but effects were attributable to increased wall stress rather than to reduced myocardial contractility. These effects persisted for at least 2 hours after the infusion was stopped.

Platelet alpha-granule release in cocaine users

BACKGROUND

Cocaine use has been associated with arterial occlusion resulting from platelet-rich thrombi and with an accelerated, often atypical atherosclerotic lesion that could be ascribed to platelet activation and platelet alpha-granule release.

METHODS AND RESULTS

Using a flow cytometric method to quantitate the percent of circulating activated platelets in whole blood (those that express the alpha-granule membrane protein P-selectin), we found that 5 of 25 samples from 12 long-term cocaine users had a baseline level of circulating activated platelets > 3 SD (range, 19% to 60%) above the mean (4.4 +/- 3.7%, mean +/- 1 SD) for 85 nonusers (sample n = 130). This subset resulted in a significantly higher mean baseline level of circulating activated platelets (11.8 +/- 14.4%) for all cocaine users (P = .01). By contrast, cocaine and its metabolites, at concentrations documented as obtainable during in vivo cocaine use (10(-7) to 10(-5) mol/L), had no effect on in vitro platelet activation or aggregation, either directly or in concert with platelet agonists. However, in experiments in which cocaine users received blinded infusions of placebo or cocaine, the mean percent of circulating activated platelets rose significantly (P < .05) after infusion of either placebo (peak 77 +/- 31%) or cocaine (peak 65 +/- 28%), the latter at doses resulting in peak plasma cocaine levels averaging < 10(-6) mol/L.

CONCLUSIONS

Long-term cocaine use in some subjects is intermittently associated with high basal levels of circulating platelets that have undergone alpha-granule release. The inability of cocaine and its metabolites at concentrations of 10(-7) to 10(-5) mol/L to cause platelet P-selectin expression in vitro in this study, coupled with the acute increase in circulating activated platelets observed in vivo after either cocaine or placebo infusion, suggests that in vivo platelet alpha-granule release associated with cocaine use may occur through indirect rather than direct effects of the drug.