angiography gives equivocal results. Many studies in the past have shown that significant left main disease can increase mortality, and that intervention (either coronary artery bypass graft surgery or percutaneous coronary intervention) to reduce mortality is necessary when the left main stenosis is significant. When using IVUS to determine whether an individual's left main disease is clinically significant, in terms of the desirability of physical intervention, the two most widely used parameters are the degree of stenosis and the minimal lumen area. A cross sectional area of ≤7 mm² in a symptomatic individual or ≤6 mm² in an asymptomatic individual is considered to be clinically significant and warrants intervention to improve one-year mortality. However, these exact cutoffs are up for debate and different cutoff cross-sectional areas may be used in practice depending on differing interpretations of the trial data. Validating the efficacy of new treatments Because IVUS is widely available in coronary catheterization labs worldwide and can accurately quantify arterial plaque, especially within the coronary arteries, it is increasingly being used to evaluate newer and evolving strategies for the treatment of coronary artery disease, including the statins and other approaches. See also Fractional flow reserve Intracoronary Optical Coherence Tomography References Diagnostic cardiology Medical ultrasonography Vascular procedures