Abstract 8921: Long-Term Effects of Smoking and Smoking Cessation on Exercise Stress Testing: Three-Year Outcomes From a Randomized Clinical Trial

Abstract

Background The long-term effects of continued smoking and smoking cessation on prognostic markers obtained during treadmill stress testing (TST) are unknown. This study evaluated the long-term effects of smoking cessation and continued smoking on TST parameters that predict cardiovascular disease (CVD) risk. Methods In a prospective, double-blind, randomized, placebo-controlled trial of 5 smoking cessation pharmacotherapies, symptom-limited TST was performed to determine peak METs, rate-pressure product (RPP), heart rate (HR) increase, HR reserve, and 60-second HR recovery, before and 3 years after the target smoking cessation date. Relationships between TST parameters and treatments among successful abstainers and continuing smokers were evaluated using multivariable analyses. Results At baseline, the 600 current smokers (61% female) were mean (standard deviation) 43.4 (11.5) years old and smoked 20.7 (8.4) cigarettes/day. Their exercise capacity was 8.7 (2.3) METs, HR reserve was 86.6 (9.6)%, HR increase was 81.1 (20.9) beats/minute, and HR recovery was 22.3 (11.3) beats. Cigarettes/day and pack-years were independently and inversely associated with baseline peak METs (p<0.001), RPP (p<0.01, pack-years only), HR increase (p<0.05), and HR reserve (p<0.01). After 3 years, 168 (28%) had quit smoking. Abstainers had greater improvements than continuing smokers (all p<0.001) in RPP (+2,055 mmHg*beats/minute), HR increase (+5.9 beats/minute), and HR reserve (+3.7%), even after statistical adjustment (all p<0.001). Conclusions Smokers with a higher smoking burden have lower exercise capacity, lower HR reserve, and a blunted exercise HR response. After 3 years, TST improvements suggestive of improved CVD prognosis were observed among successful abstainers, despite weight gain.