Comparisons of the effectiveness of two common procedures for Coronary Artery Disease: Percutaneous Coronary Intervention (PCI) and Coronary Artery Bypass Graft (CABG). Evidence indicates that CABG – the more invasive procedure – leads to superior long term outcomes for otherwise similar patients, though there is little consensus as to why. In this article, we propose a novel explanation: patient offsetting behavior. We hypothesize that patients who undergo the more invasive procedure, CABG, are more likely to improve their behavior – eating, exercise, smoking, and drinking – in a way that increases longevity. To test our hypothesis, we use Medicare records linked to the National Health Interview Survey to study one such behavior: smoking. We find that CABG patients are 12 percentage points more likely to quit smoking in the one-year period immediately surrounding their procedure than PCI patients, a result that is robust to alternative specifications.