Approximately 40% of cigarette smokers will die prematurely unless they can quit smoking. The relative ratio (relative risk) of smoking-related cardiovascular disease rates is greater in younger persons than in older persons, particularly for coronary artery disease and stroke. For instance, for coronary artery disease the relative risk at ages 35-64 is 2.8 for men and 3.1 for women while for the ages above 65 years the relative risk is 1.5 for males and 1.6 for women.
The relative risk for aortic aneurism is 6.2 for men and 7.1 for women with no age difference. Cigarette smokers are also more likely to develop large-vessel atherosclerosis and small-vessel disease. About 90% of peripheral vascular disease in the non-diabetic population can be caused by smoking as can about 50% of aortic aneurism. About 20-30% of coronary artery disease and about 10% of occlusive cerebrovascular disease is caused by smoking.
Smoking by persons with hypertension and hyperlipidaemia increases the cardiovascular risk significantly greater. In addition to the role of smoking in contributing to atherosclerosis, smoking promotes platelet aggregation contributing to vascular occlusion and myocardial infarction and sudden cardiac death. Cessation of smoking reduces the risk of a recurrent myocardial infarction after the first event within the first 6-12 months after cessation. (1)
Recurrent Cardiovascular events and smoking cessation
In an observational study from the Netherlands evaluating 4,673 patients, aged 61 ± 8.7 years with a recent (within 1 year) first manifestation of arterial disease were used in this study. Cox modelling were used to quantify the relation between smoking and risk of a recurrent major atherosclerotic event including stroke, MI and cardiovascular mortality. The patients were followed for a median of 7.4 years (3.7-10.8). There were 794 deaths during follow-up (16.9%) and 692 major cardiovascular events (14.8%).
Those who quit smoking had relative risk reduction of a recurrent major cardiovascular event of 34% (95%CI:12-51%) and a relative risk reduction of death of 37% (95%CI: 18-52%). On average those patients who stopped smoking after a first cardiovascular event lived about 5 years longer and postponed their second cardiovascular event by about 10 years. (2) The conclusion of this study is that irrespective of age, cessation of smoking after a first cardiovascular event leads to a substantial lower risk of a recurrent vascular event and death.
Smoking and Heart Failure
Heart failure is a deadly condition with a high mortality rate and a high hospitalization rate and substantial medical cost. It is predicted by many that the number of patients with heart failure will increase substantially in the next decades globally. Smoking is a leading cause of cardiovascular risk. This new study examined the association of smoking and incident heart failure in a multi-ethnic and ex-balanced cohort in the USA. (3) Data were extracted from the ongoing Multi-Ethnic Study of Atherosclerosis (MESA) which is evaluating the prognostic significance of subclinical cardiovascular disease.
The cohort for this study consisted of 6,792 participants. A cox proportional hazard model adjusted for traditional cardiovascular risk factors was used to evaluate the risk associated of smoking causing heart failure. The mean age was 62 years ± 10 years. There were 53% women and 61% non-white participants. A total of 279 incident cases of heart failure were diagnosed in time. The incidence rate of heart failure with reduced ejection fraction (HFrEF) was2.2 cases per 1000 person-years and for heart failure with preserved ejection fraction (HFpEF) the rate was 1.9 cases per 1000 person-years.
Smoking was associated with a significant higher rate of heart failure than non-smoking status: Hazard Ratio 2.05(95%CI: 1.36-3.09) with the increased rates of heart failure very similar for HFrEF and HFpEF cases. Former smokers were not significantly associated with the risk of heart failure.
In conclusion it was shown that smoking was significantly associated with the risk to develop heart failure regardless of gender or ethnicity.
Electronic smoking and cardiovascular risk
E-cigarettes are promoted as a smoking cessation device and less dangerous way to self-administer nicotine than conventional cigarettes. E-cigarettes and combustible cigarettes have similar effects on endothelial function which increases the risk of cardiovascular disease. This study used the Population Assessment of Tobacco and Health (PATH) data set to test for a relationship between smoking e-cigarettes and myocardial infarction using a logistic regression method. (4) There were adjustments for cigarette smoking and other clinical variables and demographic data. E-cigarettes smoking were independently associated with increased odds of 6.64 of having an MI with a dose-response as compared to never cigarette smoker who never used e-cigarettes.
The conclusion of these findings: Both e-cigarettes and combustible cigarettes are independently associated with increased risk of myocardial infarction. Recommending the use of e-cigarettes for smoking cessation is probably not the correct or safe method and e-cigarettes should not be recommended for people with a myocardial infarction or at high risk of a myocardial infarction.
Water-pipe smoking and coronary artery disease
Water-pipe smoking seems to be increasing in popularity partly because of a perception that it is not as dangerous as cigarette smoking. This study from different countries in the Middle-East evaluated excusive water-pipe smokers and compared them to non-smokers all older than 35 years of age. All participants had a CT scan of the coronary arteries to calculate the coronary artery calcium score (CAC). (5) The association of water-pipe smoking with the presence and extend of CAC was evaluated using regression analysis and adjusted for the traditional cardiovascular risk factors.
CAC was present in 41% of water-pipe smokers and in 28% of non-smokers (p=0.01) with an average score of 90.6± 400.3 Agatston units in water-pipe smokers vs. 52.4 ± 218.6 Agatston units. The odds of having CAC was 2.20 (95%CI: 1.20-4.01) in water-pipe smokers. Smoking duration and number of pipes smoked daily was significantly associated with a higher CAC. The conclusion was that water-pipe smoking was associated with twice the risk of having CAC and three times the risk of being in the high cardiovascular disease risk category accounting for other cardiovascular risk factors.
THIS IS THE SECOND OF TWO CPDs FOR MEDICAL CHRONICLE’S DECEMBER/JANUARY 2019 ISSUE. YOU CAN ACCESS THE QUIZ HERE.
1. Combustible cigarette smoking is a well-known and potentially treatable cardiovascular risk factor. In fact, smoking cessation is more effective than any pharmacological drug to reduce the risk of cardiovascular disease.
2. E-cigarette smoking and water-pipe smoking is also associated with a significantly increased risk of cardiovascular disease and these methods of smoking should not be encouraged.