Cigarette smoking and ventricular arrhythmia in coronary heart disease

Investigating the impact of smoking habits through photoplethysmography analysis

Smoking is widely recognized as a significant risk factor in the progression of arterial stiffness and cardiovascular diseases. Valuable information related to cardiac arrhythmias and heart function can be obtained by analyzing biosignals such as the electrocardiogram (ECG) and the photoplethysmogram (PPG). The PPG signal is a non-invasive optical technique that can be used to evaluate the changes in blood volume, and thus it can be linked to the health of the vascular system.Objective. In this study, the impact of three smoking habits-cigarettes, shisha, and electronic cigarettes (e-cigarettes)-on the features of the PPG signal were investigated.Approach. The PPG signals are measured for 45 healthy smokers before, during, and after the smoking session and then processed to extract the morphological features. Quantitative statistical techniques were used to analyze the PPG features and provide the most significant features of the three smoking habits. The impact of smoking is observed through significant changes in the features of the PPG signal, indicating blood volume instability.Main results. The results revealed that the three smoking habits influence the characteristics of the PPG signal significantly, which presentseven after 15 min of smoking. Among them, shisha has the greatest impact on PPG features, particularly on heart rate, systolic time, augmentation index, and peak pulse interval change. In contrast, e-cigarettes have the least effect on PPG features. Interestingly, smoking electronic cigarettes, which many participants use as a substitute for traditional cigarettes when attempting to quit smoking, has nearly a comparable effect to regular smoking.Significance. The findings suggest that individuals who smoke shisha are more likely to develop cardiovascular diseases at an earlier age compared to those who have other smoking habits. Understanding the variations in the PPG signal caused by smoking can aid in the early detection of cardiovascular disorders and provide insight into cardiac conditions. This ultimately contributes to the prevention of the development of cardiovascular diseases and the development of a health screening system.

Addictive drugs, arrhythmias, and cardiac inward rectifiers

In many addictive drugs including alcohol and nicotine, proarrhythmic effects were reported. This review provides an overview of the current knowledge in this field (with a focus on the inward rectifier potassium currents) to promote the lacking data and appeal for their completion, thus, to improve understanding of the proarrhythmic potential of addictive drugs.

Premature atrial complexes in an ischemic stroke population and risk of recurrent stroke: a systematic review

INTRODUCTION

Premature atrial complexes (PACs) have been proposed as a possible mediator between normal sinus rhythm and atrial fibrillation (AF). The aim of this study was to summarize the available knowledge of association between PACs and recurrent stroke or transient ischemic attack (TIA) in ischemic stroke patients. Areas covered: In this systematic review, we investigated the risk of recurrent events in patients who experienced ischemic stroke or TIA. Occurrence of PACs in electrocardiographic monitoring after index stroke/TIA was required. We identified and included three observational cohort studies, investigating in total 1005 patients. The studies reported that a significant burden of PACs occurred in a high proportion of stroke and TIA patients. More PACs were independently associated with an increased risk of recurrent stroke or TIA or the composite of recurrent stroke/TIA or death. Definition of PACs cut-off as well as patient characteristics differed between groups. Expert Commentary: This review supports an association between higher burden of PACs and recurrent stroke, and stresses the need for studies on PACs in stroke patients. A special awareness of stroke patients with a high PACs load is recommendable particularly for assessing the intensity and duration toward AF progression, and possible future treatment recommendations.

Environmental and occupational particulate matter exposures and ectopic heart beats in welders

OBJECTIVES

Links between arrhythmias and particulate matter exposures have been found among sensitive populations. We examined the relationship between personal particulate matter ≤2.5 µm aerodynamic diameter (PM2.5) exposures and ectopy in a panel study of healthy welders.

METHODS

Simultaneous ambulatory ECG and personal PM2.5 exposure monitoring with DustTrak Aerosol Monitor was performed on 72 males during work and non-work periods for 5-90 h (median 40 h). ECGs were summarised hourly for supraventricular ectopy (SVE) and ventricular ectopy (VE). PM2.5 exposures both work and non-work periods were averaged hourly with lags from 0 to 7 h. Generalised linear mixed-effects models with a random participant intercept were used to examine the relationship between PM2.5 exposure and the odds of SVE or VE. Sensitivity analyses were performed to assess whether relationships differed by work period and among current smokers.

RESULTS

Participants had a mean (SD) age of 38 (11) years and were monitored over 2993 person-hours. The number of hourly ectopic events was highly skewed with mean (SD) of 14 (69) VE and 1 (4) SVE. We found marginally significant increases in VE with PM2.5 exposures in the sixth and seventh hour lags, yet no association with SVE. For every 100 μg/m(3) increase in sixth hour lagged PM2.5, the adjusted OR (95% CI) for VE was 1.03 (1.00 to 1.05). Results persisted in work or non-work exposure periods and non-smokers had increased odds of VE associated with PM2.5 as compared with smokers.

CONCLUSIONS

A small increase in the odds of VE with short-term PM2.5 exposure was observed among relatively healthy men with environmental and occupational exposures.

Long-term mortality risk in individuals with atrial or ventricular premature complexes (results from the Third National Health and Nutrition Examination Survey)

Premature ectopic beats are frequently detected on routine 12-lead screening electrocardiograms (ECGs). However, their prognostic importance in subjects without known cardiovascular disease (CVD) is not well established. We evaluated prognostic value of atrial premature complexes (APCs) and ventricular premature complexes (VPCs) detected by a single 12-lead electrocardiography. A prospective cohort of 7,504 participants selected from nationally representative community-dwelling subjects living in the United States, enrolled in the Third National Health and Nutrition Examination Survey III from 1988 to 1994 with follow-up through December 2006 without known CVD. The main outcomes were all-cause mortality, CVD-related mortality, and ischemic heart disease (IHD)-related mortality. Of 7,504 participants (mean age 60 ± 14 years, 47% women, 49% whites), 89 (1.2%) had APCs and 110 (1.5%) had VPCs on 12-lead ECGs. During a follow-up of up to 18 years, 2,386 deaths occurred, of which 963 were due to CVD and 511 were due to IHD. In a multivariate analysis adjusted for demographics, clinical variables, and electrocardiographic measures, APCs were significantly associated with all-cause mortality (hazard ratio [HR] 1.41, 95% confidence interval [CI] 1.08 to 1.80), CVD death (HR 1.78, 95% CI 1.26 to 2.44), and IHD death (HR 2.40, 95% CI 1.59 to 3.47). For VPCs, however, there were no significant associations with all-cause mortality (HR 1.05, 95% CI 0.80 to 1.36), CVD death (HR 0.96, 95% CI 0.62 to 1.43), and IHD death (HR 0.89, 95% CI 0.47 to 1.52). In conclusion, APCs, but not VPCs, on routine screening ECGs are predictive of adverse events in community-dwelling subjects without known CVD.

Association between smoking and outcomes in older adults with atrial fibrillation

Tobacco smoking is a risk factor for atrial fibrillation (AF), but little is known about the impact of smoking in patients with AF. Of the 4060 patients with recurrent AF in the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial, 496 (12%) reported having smoked during the past two years. Propensity scores for smoking were estimated for each of the 4060 patients using a multivariable logistic regression model and were used to assemble a matched cohort of 487 pairs of smokers and nonsmokers, who were balanced on 46 baseline characteristics. Cox and logistic regression models were used to estimate the associations of smoking with all-cause mortality and all-cause hospitalization, respectively, during over 5 years of follow-up. Matched participants had a mean age of 70 ± 9 years (± S.D.), 39% were women, and 11% were non-white. All-cause mortality occurred in 21% and 16% of matched smokers and nonsmokers, respectively (when smokers were compared with nonsmokers, hazard ratio=HR=1.35; 95% confidence interval=95%CI=1.01-1.81; p=0.046). Unadjusted, multivariable-adjusted and propensity-adjusted HR (95% CI) for all-cause mortality associated with smoking in the pre-match cohort were: 1.40 (1.13-1.72; p=0.002), 1.45 (1.16-1.81; p=0.001), and 1.39 (1.12-1.74; p=0.003), respectively. Smoking had no association with all-cause hospitalization (when smokers were compared with nonsmokers, odds ratio=OR=1.21; 95%CI=0.94-1.57, p=0.146). Among patients with AF, a recent history of smoking was associated with an increased risk of all-cause mortality, but had no association with all-cause hospitalization.

Cigarette Smoking and the Risk of Supraventricular and Ventricular Tachyarrhythmias in High-Risk Cardiac Patients with Implantable Cardioverter Defibrillators

INTRODUCTION

Nicotine elevates serum catecholamine concentration and is therefore potentially arrhythmogenic. However, the effect of cigarette smoking on arrhythmic risk in coronary heart disease patients is not well established.

METHODS AND RESULTS

The risk of appropriate and inappropriate defibrillator therapy by smoking status was analyzed in 717 patients who received an implantable cardioverter defibrillator (ICD) in the Multicenter Automatic Defibrillator Implantation Trial-II. Compared with patients who had quit smoking before study entry (past smokers) and patients who had never smoked (never smokers), patients who continued smoking (current smokers) were significantly younger and generally had more favorable baseline clinical characteristics. Despite this, the adjusted hazard ratio (HR) for appropriate ICD therapy for fast ventricular tachycardia (at heart rates >or=180 b.p.m) or ventricular fibrillation was highest among current smokers (HR = 2.11 [95% CI 1.11-3.99]) and intermediate among past smokers (HR = 1.57 [95% CI 0.95-2.58]), as compared with never smokers (P for trend = 0.02). Current smokers also exhibited a higher risk of inappropriate ICD shocks (HR = 2.93 [95% CI 1.30-6.63]) than past (HR = 1.91 [95% CI 0.97-3.77]) and never smokers (P for trend = 0.008).

CONCLUSIONS

In patients with ischemic left ventricular dysfunction, continued cigarette smoking is associated with a significant increase in the risk of life-threatening ventricular tachyarrhythmias and inappropriate ICD shocks induced by rapid supraventricular arrhythmias. Our findings stress the importance of complete smoking cessation in this high-risk population.

Smoking cessation and arrhythmic death: the CAST experience. The Cardiac Arrhythmia Suppression Trial (CAST) Investigators

OBJECTIVES

This study was performed to assess the effect of cigarette smoking cessation on overall mortality and the incidence of arrhythmic death in the population of the Cardiac Arrhythmia Suppression Trial (CAST).

BACKGROUND

Cigarette smoking is a known risk factor for sudden cardiac death. Some of the adverse effects of smoking have been shown to dissipate with smoking cessation, but the time frame over which these changes occur and the population that stands to benefit have not been well delineated. CAST was a multicenter double-blind placebo-controlled study to determine whether suppression of ventricular ectopic activity by means of antiarrhythmic drugs in patients with left ventricular dysfunction after acute myocardial infarction would reduce the incidence of arrhythmic death.

METHODS

Of 2,752 patients randomized to blinded therapy, 1,026 were smoking at the time of their baseline examination and completed a 4-month follow-up visit. Of these, 517 stopped smoking by the time of this visit ("quitters") and 509 continued to smoke ("smokers").

RESULTS

Over a mean follow-up period of slightly < 16 months, there were 17 arrhythmic deaths and 32 total deaths among the quitters versus 30 and 45, respectively, among the smokers; these differences were of marginal statistical significance. Most of the fatal events occurred in a group at high risk of ongoing ischemia: the 558 patients who did not have thrombolysis or undergo revascularization after their qualifying myocardial infarction. In this high risk cohort, smoking cessation greatly reduced the incidence of arrhythmic death and was associated with a statistically significant benefit in survival.

CONCLUSIONS

Smoking cessation was accompanied by a marked reduction in arrhythmic death and overall mortality that achieved statistical significance in a high risk cohort. These data imply that smoking cessation is important in risk factor reduction in patients with advanced ischemic heart disease.

The effects of smoking on the signal-averaged electrocardiogram in normal subjects

Tobacco smoking increases the risk of sudden cardiac death, possibly by altering the substrate for propagation or sustainment of ventricular tachyarrhythmias. To test this hypothesis, 15 long-term smokers without known coronary artery disease abstained from tobacco smoking for 12 h, after which they underwent SAECG before, 15 min after and 30 min after smoking two cigarettes. Other than minor lengthening of filtered QRS duration, no significant change in time-domain SAECG parameters was noted. We conclude that late potentials are not produced by cigarette smoking and that ventricular arrhythmia substrate as measured by SAECG variables is not worsened in long-term smokers without evidence of coronary artery disease.

Effect of cigarette smoking on the frequency of ventricular premature complexes in normal subjects

1. Ambulatory ECG monitoring was undertaken in healthy cigarette smokers (33) and non-smokers (20) of similar age (21-66 years). 2. The frequency of ventricular premature complexes (VPC) was less in habitual smokers (P less than 0.05; Mann-Whitney rank test) and an average of more than 1 VPC per hour occurred in a higher proportion of non-smokers than smokers: eight of 20 (40%) vs two of 33 (6%) (P less than 0.01; Chi-square test).

Cardiovascular effects of smoking in patients with ischemic heart disease

The cardiovascular effects of smoking, including the occurrence of ventricular arrhythmias, were examined in 52 patients with ischemic heart disease. The study was a randomized, crossover comparison between smoking six cigarettes and nonsmoking with observer-blinded primary outcome measurements. Continuous Holter ECG recording for four hours showed no significant differences in the proportion of patients experiencing ventricular ectopy or the total number and complexity of ventricular premature beats during smoking vs nonsmoking. Aside from the first cigarette, smoking did not significantly alter blood pressure or heart rate. Mean (+/- SEM) plasma epinephrine (pg/ml) increased (p = 0.02) from baseline (52 +/- 4) to a maximum of 64 +/- 6 at 240 minutes with younger subjects exhibiting a more marked rise (p = 0.02) than subjects over 55 years of age. Plasma norepinephrine was unchanged by smoking. A power calculation confirmed the conclusion that the resumption of smoking after overnight abstention does not acutely increase the occurrence of ventricular ectopic activity in patients with ischemic heart disease.

Electrophysiologic effects of cigarette smoking in patients with and without chronic beta-blocker therapy

After refraining from smoking for at least 8 hours, 22 adult male habitual smokers underwent baseline electrophysiologic study including atrial and ventricular burst pacing and programmed premature stimulation with single extrastimuli. After smoking 2 of their usual brand of cigarettes in rapid succession, the electrophysiologic protocol was repeated. Nicotine, catecholamine and carbon monoxide concentrations all increased significantly. Smoking increased heart rate and improved atrioventricular conduction in the 13 patients receiving chronic beta-blocker therapy (mostly for angina pectoris); increases in heart rate and improvement in atrioventricular conduction were not different statistically from those seen in patients not receiving beta-blocker therapy, suggesting the possibility of a direct effect of nicotine or other components of tobacco smoke. Ventricular refractoriness was not altered and atrial and ventricular arrhythmias were not increased by smoking. Persistent sympathomimetic actions of cigarette smoking may explain in part the failure of beta-blocking drugs to reduce cardiac mortality risk in smokers after myocardial infarction.