Researchers’ Corner: Smoking And Drinking Has No Significant Effect On All Causes Of Death In Patients With DCM

The opinion in this research is strictly that of the researchers and not emobileclinic.

A recent study shows no significant differences in mortality between the smoking- and drinking-related patient groups, indicating no effect of smoking and drinking on all-cause mortality in patients with DCM in the present large-scale study.

Past studies have shown that smoking and drinking are associated with poorer outcomes in patients with cardiomyopathy. The researchers’ main aim  was to determine all-cause mortality in dilated cardiomyopathy (DCM) associated with smoking and drinking.

What is DCM

Simply refers to as Dilated cardiomyopathy (DCM), a disease of the heart muscle characterized by ventricular dilatation and impaired systolic function. It is the third most common cause of heart failure. The prognosis of patients with DCM is poor, with approximately half of the patients dying within 5 years of diagnosis, and it is necessary for the physician to predict which clinical course an individual patient may follow.

Cigarette smoking is a major modifiable risk factor for cardiovascular diseases, including coronary artery disease, stroke, peripheral vascular disease and congestive heart failure . Both smoking and exposure to passive smoke are major preventable causes of cardiovascular morbidity and mortality . Previous studies have indicated that smoking is related to cardiomyopathy and is an important risk factor for idiopathic congestive cardiomyopathy.

 

What Recent Study Says

However, recent studies have suggested that patients with DCM who smoke have a better prognosis than that of nonsmokers , although data from New Zealand show that smoking is associated with poorer survival in patients with DCM .Although heavy drinking and smoking are known risk factors for cardiovascular mortality, their roles in DCM patients remain unclear. Therefore, the present study evaluated the association of drinking and smoking with all-cause mortality in hospitalized patients with DCM in China using a large scale cohort sample.It investigated the associations between smoking, drinking and all-cause mortality in patients with DCM and  findings suggested that there was no predictive value of smoking and drinking for all-cause mortality in DCM patients .The research says neither smoking nor drinking was an independent predictor of the all-cause mortality in patients with DCM.

The researchers pointed that tobacco smoking has been solidly implicated in the etiology of cardiovascular diseases such as coronary artery disease, aortic aneurysm, stroke and peripheral vascular diseases , as cigarette smoking has been associated with higher serum levels of cholesterol, coronary vasomotor reactivity, platelet aggregation, and a prothrombotic state. Additionally, an association between smoking and cardiomyopathy has been suggested by the results of several research animal studies where possible mechanisms underlying the association between smoking and cardiomyopathy include direct damage to cardiac muscles (following damage to the myocardial mitochondria) and an increase in cardiac susceptibility to viral infections .

However the recent study shows the effect of smoking on the mortality of DCM patients cannot be conclusively determined based on the available data . In the present study, there was no detectable influence of mild-to-moderate smoking and heavy smoking on the all-cause mortality in DCM patients.Although the all-cause mortality rate was lower among mild-to-moderate smokers than among non-smokers, this association did not achieve statistical significance.In this present large-sample cohort study, although heavy drinkers were excluded owing to alcoholic cardiomyopathy, no significant differences were found between patients who were non-drinkers, mild drinkers and moderate drinkers.

What Previous Studies Said?

Previous studies have found that that heavy drinkers exhibit a lower ejection fraction, greater end-diastolic volume, increased left atrial dimensions and increased left ventricular wall thickness, which occur in a dose-dependent fashion and precede the onset of clinical symptoms or physical findings . The mechanisms underlying alcohol-induced myocardial damage include cardiac myocyte apoptosis , alterations in the excitation–contraction coupling in cardiac myocytes , and increased oxidative stress and activation of the renin–angiotensin system and the sympathetic nervous system . However, moderate alcohol consumption has been proposed to confer protection against cardiovascular events, increases high-density lipoprotein cholesterol, decreases platelet aggregation and coagulation, enhancing endothelial function, reducing inflammation, promoting antioxidant effects and decreases the activity of angiotensin II (Ang II) .

Past Studies in mice and humans have shown that alcohol is a direct myocardial toxin that causes ultrastructural damage. Heavy drinking has been associated with left ventricular dysfunction and DCM, referred to as alcoholic cardiomyopathy . According to most studies, heavy drinking is associated with increased cardiovascular morbidity and mortality .

The US National Health and Nutrition Examination has stated that alcohol consumption has a linear relationship with mortality, with a slightly higher mortality risk for even light drinking . However, some studies have shown that moderate alcohol consumption has cardioprotective effects; reduces the risk of chronic heart failure, coronary artery disease and stroke; and decreases cardiovascular and all-cause mortality.

In a study of patients with a previous myocardial infarction, those who consumed small-to-moderate amounts of alcohol exhibited a lower total mortality . However, the present study found no favorable effect of mild-to-moderate drinking on the all-cause mortality in the DCM patients.

How the researchers arrived at their Conclusion

An observational cohort study was undertaken in DCM patients from November 2003 to September 2011. A total of 1118 patients were enrolled, with a mean follow-up of 3.5 ± 2.3 years. Standard demographics were obtained, and transthoracic echocardiography and routine blood testing were performed shortly after admission. Outcome assessment was based on the all-cause death after admission.

More Information

British Medical Journal

‘The effects of smoking and drinking on all-cause mortality in patients with dilated cardiomyopathy: a single-center cohort study’

A work of Xiaoping Li .Etal