Substance Abuse and the Heart

65 Substance Abuse and the Heart



David A. Tate


Substance abuse has enormous social, economic, and medical consequences. Although abuse of both legal and illegal substances can have adverse effects on the cardiovascular system, as discussed in this chapter, it is important to note that two legal substances—tobacco and alcohol—have the greatest impact on cardiovascular health of citizens of the United States and other industrialized countries (Fig. 65-1, upper and middle).


image

Figure 65-1 Substance abuse and the heart.


ETOH, ethyl alcohol; HDL-C, high-density lipoprotein cholesterol; HTN, hypertension; IV, intravenous; LDL-C, low-density lipoprotein cholesterol; MI, myocardial infarction.



Tobacco


From a cardiologic perspective, given the impact of smoking on coronary artery disease, tobacco is by far the most lethal of abused substances. Although the adverse effects of smoking on atherosclerotic disease have been known for years, studies continue to emphasize the striking magnitude of the effect. The incidence of coronary disease in smokers is approximately twice the incidence in nonsmokers. The deleterious effects of smoking were recently demonstrated in the Women’s Health Study, which suggested that half of all coronary deaths in women could be attributed to smoking. In primary prevention trials of the use of statins for hypercholesterolemia, coronary event rates were 74% to 86% higher in smokers than in nonsmokers. Following myocardial infarction (MI), recurrent MI is twice as frequent among those who continue to smoke compared with those who quit. It can therefore be argued that smoking cessation is likely to be more effective than statins for primary prevention of cardiovascular disease and more effective than aspirin, β-blockers, or angiotensin-converting enzyme inhibitors for secondary prevention. Despite a decline in smoking in recent decades, approximately 20% of adult Americans remain addicted to tobacco. Moreover, smoking among adolescents, particularly young women, rose for several years and has shown no decline in recent years.


The medical and lay communities share a pessimistic view of smoking cessation that may not be fully justified. Caregivers must recognize that tobacco is a genuinely addictive substance, documented as such by the U.S. Surgeon General’s Office. It must also be acknowledged that smokers who want to quit often fail in their attempts to stop smoking. Nevertheless, many smokers do ultimately succeed in quitting, and by facilitating smoking cessation, the health care provider is likely to have a more salutary effect on a patient’s health than with almost any other medical intervention. Counseling by physicians makes a difference, and the efficacy of counseling is directly related to the intensity of the counseling program. Efficacy can be greatly increased by the use of questionnaires, written materials, and follow-up. Smoking cessation rates are also substantially increased when a cardiovascular event has heightened patient concern. In a group of smokers with MI, cessation rates of 24.5% with standard advice and 63.2% with intensive advice were achieved.


Several pharmacologic adjunctive agents for smoking cessation are available that increase success rates beyond counseling alone. In a standard outpatient setting, modest but significant success has been achieved with nicotine replacement therapy, with abstinence rates of approximately 20% at 1 year. Considerable success has also been achieved with bupropion, which affects noradrenergic and dopaminergic function in the central nervous system; this has resulted in approximately a twofold increase in successful smoking cessation. Modest additional efficacy has been apparent when nicotine replacement therapy is combined with bupropion. The most recently approved pharmacologic therapy for smoking cessation is varenicline. This partial agonist of nicotinic acetylcholine receptors seems to be somewhat more effective than bupropion, with abstinence rates at 1 year of 23% versus 16% with bupropion in one study. Side effects of nausea or abnormal dreams may limit therapy, however, and there have been reports of suicidal thoughts and erratic behavior in some patients.


Regardless of the method, it is clear that determining a specific “quit day” enhances the chance of success, as opposed to gradual tapering. Thus, physicians should advise their patients on the hazards of smoking and assess their readiness to quit. In those who seem motivated, intensive initial counseling and follow-up supportive care should be provided and adjunctive pharmacologic therapy offered. Given the remarkable reduction in cardiovascular morbidity and mortality that occurs with smoking cessation, aggressive efforts at helping patients to stop smoking are warranted.



Alcohol


Alcohol abuse takes an enormous toll, with the strictly medical effects (e.g., liver disease, pancreatitis) compounded by the sociobehavioral health effects (e.g., suicide, homicide, trauma, domestic abuse). The effect of alcohol on the heart, however, is complex, with a mix of adverse and possibly beneficial effects.


The apparent beneficial effect of modest alcohol intake was first noted in France, where a surprisingly low coronary disease mortality rate was observed despite a high intake of dietary fat. This observation came to be called the “French paradox.” Since this initial observation, a J-shaped relationship between alcohol intake and total mortality has been defined. The initial descending portion of the curve derives from the reduced cardiovascular mortality associated with modest alcohol intake (one to three drinks per day). Although the effect may be somewhat more apparent with red wine (and related to the potential cardioprotective effects of nonalcohol components of red wine), most evidence suggests that the majority of the beneficial effect is from alcohol per se. The mechanism may relate to a variety of factors, including increased high-density lipoprotein cholesterol, decreased low-density lipoprotein cholesterol, antioxidant effects, decreased platelet aggregation, and enhanced fibrinolysis.


It is important to note that despite this finding, there are no controlled trials that suggest a benefit from advising or instigating modest alcohol intake. The potential beneficial effect must be weighed against the catastrophic effect of immoderate consumption or even of moderate consumption in at-risk segments of the population (e.g., genetic risk for alcoholism, women of childbearing age, drivers). Thus, it is likely that an intervention trial would demonstrate both positive and negative effects, and for this reason it is unlikely that this question will ever be studied in a prospective, randomized trial.

Related posts:

  1. Angiogenesis and Atherosclerosis
  2. Syncope
  3. Interventional Approaches for Peripheral Arterial Disease
  4. Aortic Regurgitation

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Jun 12, 2016 | Posted by in CARDIOLOGY | Comments Off on Substance Abuse and the Heart

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