Smoking Can Up Risk of Delivered ICD Therapy in Mild HF

February 14, 2014

ROCHESTER, NY — Current smoking ups the risk of ventricular tachyarrhythmias (VTAs) that elicit a treatment response from implanted defibrillators, either shocks or pacing, in patients with mild systolic heart failure, according to a new analysis from the MADIT-CRT trial[1].

The observed significant jump in incident VTA risk was relative to patients who had never smoked or had previously quit smoking. And the effect seemed more pronounced among patients with ischemic cardiomyopathy and weaker in those with nonischemic heart disease.

"Furthermore, after having a first VTA event, both ischemic and nonischemic smokers were at increased risk for recurrent ventricular tachyarrhythmias when compared with their nonsmoker counterparts," write the authors, led by Dr Benjamin Plank (University of Rochester Medical Center, NY).

"These findings suggest a strong proarrhythmic effect of smoking, and therefore smoking cessation should be strongly encouraged in mild heart-failure patients with ventricular dysfunction."

MADIT-CRT randomized 1820 patients who were in NYHA class 1–2 heart failure with LVEF <30% and QRS-defined ventricular dyssynchrony to receive a defibrillating cardiac resynchronization therapy device (CRT-D group) or defibrillation only (implantable cardioverter defibrillators [ICD] group). Patients with ischemic cardiomyopathy could be in NYHA class 1 or 2 and those with nonischemic disease had to be in NYHA class 2.

As reported by heartwire in September 2009, the adjusted risk of death or heart-failure events fell 34% (p=0.001) in the CRT-D group compared with the ICD group over an average of 2.4 years.

The current analysis included the 79% of MADIT-CRT patients who were initially no older than 75 and had adequate data. They were categorized according to smoking status: current smokers (n=197), past smokers (n=780), and never-smokers (n=465).

In multivariate analysis, current smokers showed a significantly higher risk of incident VT/ventricular fibrillation (VF) or death and a higher risk of incident VT/VF only, compared with nonsmokers. Past smokers and never-smokers had similar risks for all measured end points.

Outcome All Patients Ischemic Nonischemic
VT/VF or death HR (95% CI); p HR (95% CI); p HR (95% CI); p
Current vs nonsmokers 1.51 (1.14–2.01); 0.005 1.55 (1.06–2.28); 0.026 1.41 (0.90–2.20); 0.134
Current vs past smokers 1.50 (1.17–1.93); 0.002 1.65 (1.20–2.29); 0.002 1.23 (0.81–1.87); 0.338
VT/VF HR (95% CI); p HR (95% CI); p HR (95% CI); p
Current vs nonsmokers 1.54 (1.12–2.13); 0.008 1.67 (1.08–2.60); 0.023 1.31 (0.80–2.15); 0.290
Current vs past smokers 1.41 (1.06–1.86); 0.017 1.53 (1.07–2.20); 0.020 1.16 (0.73–1.86); 0.532

Adjusted for CRT-D treatment, sex, LV end-systolic-volume index, prior MI, prior HF hospitalization, prior ventricular arrhythmia, QRS duration, and prior coronary revascularization

Compared with nonsmokers, current smokers showed a 54% higher risk of recurrent VTA risk (p<0.001), a risk elevation that remained at about the same level and degree of significance whether the patients had ischemic or nonischemic disease.

But in the subgroup of patients with nonischemic disease, current smokers had a 48% increased risk of recurrent VTA events (p=0.035).

"While it has previously been demonstrated that smokers with ischemic cardiomyopathy and moderate heart-failure symptoms have an increased risk of VTA, this is the first study to compare the risk in nonischemic patients with mild heart-failure symptoms," the authors write.

"The effects of smoking seem to be attenuated in patients with nonischemic cardiomyopathy, likely due to the overall lower risk of ventricular arrhythmias in patients with nonischemic LV dysfunction. However, the risk of recurrent ventricular tachyarrhythmias was [still] observed to be significantly higher in nonischemic smokers compared with their nonsmoker counterparts."

Plank declared no conflicts of interest. Disclosures for the coauthors are listed in the paper.

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