Attenuated predictive power of a normal myocardial perfusion scan in young smokers.

Abstract

BACKGROUND: The negative predictive value of a normal myocardial perfusion image (MPI) for myocardial infarction or cardiac death is very high. However, it is unclear whether a normal MPI, reflecting non-compromised blood flow in the stable state, would have the same prognostic implications in smokers as in patients who do not smoke. METHODS: The incidence of total mortality, cardiovascular mortality, and myocardial infarction was evaluated in 11,812 subjects (14.6% of whom were current smokers at the time of the study) with a normal MPI study and no past history of coronary artery disease during the period 1997 to 2008. RESULTS: During an average follow-up of 72.4 ± 32.4 months the risk for an acute myocardial infarction in current smokers was approximately 50% higher than the corresponding risk in non-smokers, despite a younger average age. Cox proportional regression models show that current smoking was associated with an increased hazard rate for the composite endpoint below age 60 (HR=2.09, 95%CI 1.43-3.07, p<0.001), but not at older ages (HR=1.16, 95% CI 0.81-1.66, p=0.4). CONCLUSIONS: In individuals below age 60, but not at older ages, current smoking is associated with increased short- and long-term risk of cardiac death and acute myocardial infarction even in subjects with a normal MPI.