How to assess severity of a lesion in LAD in a patient with TVCAD when LAD also cross fills RCA? How can you reliably interpret FFR in this LAD, if RCA CTO can not be opened? Should you rely on some other modality in such patients?
64 years old diabetic gentleman who had PCI to mid LAD 2 years back, now presents with angina CCS III. Coronary angiogram showed patent stent in LAD with a moderate (?) stenosis after the stent. Critical disease in LCX and totally occluded dominant RCA being cross filled from LAD. Severity of mid LAD lesion was debatable on eyeballing. FFR in the presence of a large RCA cross fill can be significant in LAD even with a moderate lesion due to the increased vascular bed of LAD and hence not as reliable. Opening the RCA first and then doing FFR in LAD would be an ideal situation but the patient personally prefers CABG if his LAD is significant and hence does not want PCI to RCA before assessment of LAD. SPECT (Thallium) scan in presence of TVCAD may give us the overall severity of disease burden by presence of lung uptake etc but will not be able to access the individual severity of LAD disease to guide for LAD intervention. As far as IVUS is cocerned, Dr SJ Park and colleagues have now brought down the MLA for epicardial arteries from 4mm2 to 2.4mm2 and this correlates with FFR of <0.80(Sensitivity 90%, Specificity 60 % with PPV 37% and NPV 96%). What they recommend is that " IVUS-derived MLA>2.4 mm2 may be useful to exclude FFR<0.80, but poor specificity limits its value for physiological assessment of lesions with MLA<2.4 mm2"( Kang SJ, et al, Circ Cardiovasc Interv. 2011;4: 65-71).
How would you assess the severity of this mid LAD lesion? Can we reliably interpret FFR in presence of a cross filling ?