Impact of coronary artery bypass graft surgery in smoking cessation

Resumo Fundamento: Tabagismo é um importante fator de risco modificável para doença cardiovascular. Poucos estudos têm investigado a frequência da cessação de fumar entre pacientes submetidos à doença cardíaca. Objetivos: Determinar a frequência da cessação de fumar em pacientes submetidos à cirurgia de revascularização do miocárdio. Métodos: Estudo de coorte, de 203 pacientes consecutivos, maiores de 18 anos, submetidos à cirurgia de revascularização do miocárdio no período de janeiro 2006 a março de 2007, quando foram entrevistados em relação ao uso de cigarros no período pré e pós-operatório. Fumantes foram estratificados de acordo com o grau de dependência com o uso do Teste de Dependência de Fagerström. Os pacientes foram seguidos durante 60 e 90 dias para avaliar uso de cigarros. Resultados: A média de idade do grupo foi de 62 ± 10 anos, e 134 (66%) eram homens. Antes da cirurgia, 146 (71,9%) pacientes eram fumantes. Um número significativo de pacientes parou de fumar no período pós-operatório: 136 (93,15%) e 137 (93,84%), aos 60 e 90 dias, respectivamente, pararam de fumar depois da cirurgia. Conclusão: Cirurgia de revascularização do miocárdio é um importante determinador para cessação de fumar.


INTRODUCTION
Despite the anti-tobacco use campaigns, more than 1 in 10 cardiac patients died in the world in 2000 due to causes related to tobacco use, showing that it is an important cause of cardiovascular mortality [1].Patients that kept on smoking after the coronary artery bypass graft surgery (CABGS) present higher risk of death than those patients ceased smoking.They are also submitted to procedures of revascularization more frequently [2].In spite of these perspectives, quitting smoking is a challenge for many people.Although it is estimated that 70% of smokers worldwide would like to get rid of their addiction, only one third has success each year [3,4].Several psychotherapy approaches, associated or not to pharmacologic treatments such as reposition of nicotine or bupropion, have been used, showing evidences of 10%-25% of efficiency in different clinical experiments [5].It becomes a must to identify situations and strategies that can improve the efficiency of treatments for tobacco use.In all therapy approaches, cease smoking is one of the most crucial factors [6].Crisis situations and events involving serious health risks, such as acute infarction of the myocardium, hospitalization, surgery and loss of relatives due to tobacco use related diseases, may represent an important motivation in order to cease smoking [7][8][9][10][11][12][13][14].
A limited number of studies have shown that CABGS in patients with ischemic disease represent a strong influence in order to cease smoking [15][16][17][18].The factors involving these situations and the degree of nicotine addiction in this group of patients are not well understood.This study aimed to investigate the frequency of smoking cessation between patients submitted to CABGS.

METHODS
This prospective cohort analyzed 203 consecutive patients submitted to CABGS, between January, 2006 and March, 2007 (in the preoperative and postoperative periods), in three University Hospitals: Instituto de Cardiologia do Rio Grande do Sul (ICRS), Hospital de Clínicas de Porto Alegre (HCPA) and Irmandade Santa Casa de Misericórdia de Porto Alegre (ISCM).All adult patients, of both genders, and receiving medical care in each hospital.The professionals involved in the therapy procedures were not aware of the research project.There was no systematic approach for smoking cessation with these patients.
The study was approved by the Ethics Committee of the three hospitals involved.The patients that agreed to take part in this study signed up an agreement term.Patients were interviewed 60 and 90 days after CABGS regarding smoking cessation incidence.Further information was acquired through medical leaflets.
Patients operated in emergency or holding acute coronary syndrome or concomitant congenital heart disease and valve surgery were excluded from this study.

Research tools
Patients answered a questionnaire structured on demographic, anthropometric and clinical data.The Fagerström Nicotine Dependence Test (FNDT) [19,20] was created in 1978 and validated in Brazil by Carmo & Pueyo, being used to determine the degree of nicotine addiction [18].The patients were rated according to the FNDT [19].By using the FNDT, patients were stratified in three groups, according to the degree of nicotine dependence: a. very low and low; b. moderate; c. very high and high.
For analysis purposes, the patients stratified according to the degree of nicotine dependence by the Fagerström Test were allocated in three groups: a. very low and low degree; b. moderate degree; c. high and very high degree.The tobacco users were classified by the following criteria: a. present smoker (smoking from the date of surgery to one year earlier); b. in abstinence (smoking cessation from 1 to 20 years); c. exsmokers (smoking cessation over 20 years); d. passive smokers (cohabiting with a smoker) [14,21].The surgical risk was determined by a clinical risk score of the Cleveland Clinic [22].

Statistical analysis
The data collected were analyzed by the SPSS (Statistical Package for the Social Sciences) Program version 15.0.The categorical variables are presented by absolute frequencies and percentages and the continuous variables with normal distribution, by mean or standard deviation, whereas those without normal distribution, by mean and interquartilic amplitude (IQ).
In order to evaluate the demographic, anthropometric and clinical characteristics of the patients regarding smoking and complications, it was applied a Student's t test, for the continuous variables with symmetrical distribution, or the Mann-Whitney's test, for the variables with asymmetrical distribution, and the chi-square test or Fisher's exact test, for the categorical variables.
The logistic regression was used in order to control confusing factors and evaluate postoperative complication predictors.
The variables with P < 0.20 were used in the logistic regression model for the analysis of smoking associated with postoperative complicacies in 60 days.
In all analyses a value P < 0.05 was considered statistically significant.

Sample characteristics
There were selected 211 consecutive patients in the preoperative of CABGS.Eight patients were excluded for not having undergone surgery for different reasons.The sample of the study, thus, consisted of 203 patients, being 134 (66%) male, with mean age 62 ± 10 years.Average income was US$ 340.00 (US$ 198.00 -US$ 592.00) and 146 (71.9%) patients were smokers.
General characteristics of the sample are presented on Table 1.The groups were different, for the smoking group presented lower age patients, higher number of male patients, tendency of higher income, cohabiting with tobacco users and educational background.
There was a significant cessation of smoking in the postoperative.Out of 146 smoking patients prior to surgery, only 10 (6.85%) and nine (6.16%) continued smoking after CABGS.
The general characteristics of these patients are presented in Table 2. Patients that continued smoking presented lower age and income.
Figure 1 shows the Fagerström classification, in which patients were rated prior to CABGS, in 60 and 90 days after CABGS.The percentage of smoking cessation was also analyzed in 60 and 90 days in the stratified group according to the degree of tobacco use addiction.An expressive cessation was observed in all groups.Considering the small number of patients that kept on smoking, it cannot be observed a correlation between the degree of addiction and cessation in the postoperative (Figure 1).

DISCUSSION
This study showed that a large number of patients quit smoking within 60 or 90 days after CABGS.This percentage of smoking cessation, (93.15%) was higher than initially expected.It was the highest result ever observed so far with efficient behavioral and pharmacologic approaches observed in different studies, in which the rates ranged from 10%-25% [15][16][17][18].Our results compared to those of other studies showed high percentile of smoking cessation in patients hospitalized for CABGS.Hilleman et al. [23] studied a sample of patients submitted to CABGS and observed that 85% quit smoking.Rigotti et al. [16] performed a random controlled clinical study following patients submitted to CABGS for a year and 94% of the patients were followed up for a period of 5.5 years, in order to check the efficiency of a smoking cessation program in patients submitted to CABGS.The results showed that, even without a specific intervention, almost half of the smoking patients cease smoking, for five years, after heart surgery.
In this study there were not observed significant differences between the different degrees of nicotine dependence, in the behavior of ceasing tobacco use in the postoperative.The number of patients that kept their smoking habit was very low and, thus, that could not be inferred as the degree of addiction shows correlation or not with smoking cessation in the postoperative.Cavender et al. [24] performed a random controlled clinical study, in which the magnitude and the profile of nicotine dependence among patients submitted to CABGS were determined by the FNDT.According to the test and the patient's

Table 1 .*
Characteristics of smoking and non-smoking patients submitted to coronary artery bypass graft surgery.Results are expressed in numbers (percentile), values are expressed as numbers (percentage), except other indications.SD =Standard Deviation PIETROBON, RC ET AL-Impact of coronary artery bypass graft surgery in smoking cessation Rev Bras Cir Cardiovasc 2010; 25(1): 79-84

Fig. 1 -
Fig. 1 -Distribution of smoking patients, stratified according the degree of tobacco addiction, during the preoperative period and 60 and 90 days after coronary artery bypass graft surgery

Table 2 .
Characteristics of smoking patients submitted to coronary artery bypass graft surgery, stratified according to tobacco use in 60 days.* *Results are expressed in numbers (percentile), except others.SD =Standard Deviation