T Ago39a.p65

Mailing address: Paulo Roberto Dutra da Silva Rua General Artigas, 395/101 22441-140 Rio de Janeiro, RJ Brazil E-mail: [email protected] In the last fifteen years several randomized studies were published comparing percutaneous coronary intervention (PCI) and coronary artery bypass graft surgery (CABG) in patients with stable angina and multivessel coronary artery disease1-3. Few studies, however, have focused their designs on the presence of angina (BARI3, MASS II)4 or on the quantitative evaluation of myocardial ischemia as obtained at ergometric stress test or at myocardial perfusion scintillography1,4. Studies that compared CABG and PCI showed that mortality and q-wave myocardial infarction rates were similar either at short term (one year) or at long term (five years) follow-up for both groups. The freedom of angina advantage at one year within the CABG group was lost in the fifth year after randomization5-7. Alazráki et al8 also showed the same results using Single Photon Emission Computed Tomography (SPECT) evaluation with Thalium 201 at three years of follow-up. There was no evidence of predominant myocardial ischemia in either of the two groups. These studies correspond to a time when groups selected for randomization consisted of patients with multivessel coronary artery disease, mostly with two-vessel disease; the stents were allowed only under extraordinary conditions (bailout) and complete revascularization was achieved mainly on surgical patients. Still, at long term follow-ups, surgery did not show to be superior to PCI on death or q-wave myocardial infarction analysis. In addition, patients randomized to PCI presented similar results to those observed in the CABG group in terms of induced myocardial ischemia either on ergometric stress test evaluation or on scintillography, or even in relation to severity of angina. This was due to an elevated necessity of a new revascularization procedure in the PCI group1-4,9. Moreira et al10 designed a randomized, prospective, unicenter cohort study that compares two different revascularization strategies of the ischemic myocardium. The first group had CABG surgery in which the use of arterial grafts were encouraged. In the second group, PCI was achieved with no limits to the use of different tools to accomplish an unobstructed coronary artery, ranging from balloon-catheter and atheroablasive devices to laser and nonpharmacological stents. Their goal is to quantify and qualify myocardial ischemia at two distinct moments: M1, pre-intervention and M2, at six month follow-up. Angina evaluation, ergometric stress test and SPECT-sestamibi variables were used for that. The analysis was based on those patients successfully treated in each group by excluding acute complications and the necessity of a new revascularization procedure at the CABG and PCI groups. The angiographic variables differ between the two groups: there is a predominance in patients with triple-vessel disease and complete anatomic revascularization in the CABG group compared to the PCI group. However, the presence of angina and quantitative ischemic variables at ergometric stress test and scintillography are equivalent. Moreira et al10 conducted a well-designed and rare randomized and prospective study, predominantly in patients with multivessel coronary artery disease wth normal left ventricular function and equivalent ischemic situations. These data allowed the conclusion that the two types of myocardial revascularization treatments, at the symptomatic evaluation (angina) as well as at the quantitative ischemia evaluation through ergometric stress test and perfusion scintillography (ischemic load) comparing M1 and M2, resulted in a significant decrease of the myocardial ischemia with no difference between the two types of treatment sixth months after the procedure (M2). The limitations and critics to the work of Moreira et al10 refer to the groups of patients with a predominance of triple-vessel coronary artery diseae in the surgical group, and two-vessel disease in the PCI group. The exclusion of acute complications in both groups and the elevated percent levels of new revascularizations in the PCI group up to six months after the procedure possibly made the two groups exhibit the same degree of ischemic equivalency at M1 and M2. Thus, the authors could have demonstrated different results from those obtained regarding myocardial ischemia at ergometric stress test and at the scintillography (ischemic load) as well as concerning angina at M2, if those variables were not eliminated. Another point to be discussed and remembered refers to the lack of analysis of the coronary blood low through the graft (or coronary artery) that reaches the viable myocardium. Frequent examples are found such as graft occlusion or an artery treated by PCI, that tests with normal responses, as well as non-revascularized vessels of little anatomic importance, resulting in a ischemic response.