[What is the value of myocardial perfusion studies with isotopes in patients with complete left bundle branch block?]. / Qual o valor dos estudos de perfusão miocárdica com isótopos em doentes com bloqueio completo de ramo esquerdo?

The prognosis of left bundle branch block is determined by associated cardiovascular disease. Exercise electrocardiography is not helpful in detecting ischemia in these patients. Exercise thallium-201 scintigraphy has been widely accepted for that purpose. The authors made an overview of several studies suggesting that exercise thallium-201 scintigraphy has low specificity regarding left anterior descending coronary artery disease. They also review the mechanisms of perfusion defects in patients with left bundle branch block without coronary artery disease. One important question to be clarified is weather small defects are unrelated to coronary artery disease. Finally the authors analyse a few methods to increase diagnostic accuracy of perfusion scintigraphy in left bundle branch block. First the employment of a new criterium that requires the apex to be abnormal to indicate left anterior descendent artery disease. Second Pharmacological Stress with Dipyridamole or Adenosine. Third imaging with Tc-99m-MIBI.