Background:
A patient of effort angina who had 75% stenosis at #7 with high FFR 0.85 underwent PCI. He has had no chest pain at all since PCI.
Purpose:
To find a more reliable variable than FFR in assessing myocardial ischemia (MI) caused by coronary artery stenosis (CAS), animal experiments were done to cover three variables - coronary blood flow (Flow), myocardial PtiO2 (PtiO2) and FFR, which were compared to see which is the most reliable of the three. All the procedures were approved by Clinic’s ethical committee and carried out observing the Declaration of Helsinki of the World Medical Association.
Method:
In twelve pigs, vascular occuluders and flow meters were set at #6 and/or #7 and #11 and/or #13. PtiO2 sensor wires were inserted into the anterior and lateral LV wall transepicardially. FFR sensor wires were placed across the LAD and LCX stenoses. The data was all analyzed by a paired t-test and ROC.
Results:
Flow(ml/min): normal 54.23±5.24 and 50% 27.88±5.53, p< 0.0001; sencitivity(sen.) 1.00, specificity(spe.) 1.00, accuracy(acc.) 1.00 by ROC 38.9. 50% and 75% 17.60±6.06, p < 0.0001; sen. 0.92, spe. 0.83, acc. 0.88 by ROC 21.8. PtiO2(mmHg) : normal 54.91±6.44 and 50% 27.87±3.40, p< 0.0001; sen. 1.00, spe 1.00, acc. 1.00 by ROC 32.1. 50% and 75% 16.85±2.73, p < 0.0001; sen. 0.92, spe. 0.92, acc. 0.92 by ROC 21.7. FFR: normal 0.97±0.01 and 50% 0.89±0.06, p < 0.0001; sen. 0.92, spe. 1.0, acc. 0.96 by ROC 0.96. 50% and 75% 0.83±0.04. p < 0.0002; sen. 0.75, spe. 0.75, acc. 0.75 by ROC 0.86. Thus PtiO2 was the most reliable variable in assessing MI of CAS among three.
To confirm clinical application of PtiO2 , animal experiments using ten pigs was conducted to measure it through coronary artery. 0.5 mm transepicardial sensor wires were attached to the tips of upside-down 0.014 inch guiding wires. The guiding wires perforated LADs and were pushed into myocardium to measure PtiO2 (normal 55.54±3.57, 50% 28.08±2.48, 75% 17.1±2.85). These data showed no significant difference from the transepicardial data described above. A leak of contrast agent through a tiny perforation had expired in ten minutes.
Conclusion:
The results proved PtiO2 was the more reliable valiable than FFR, showing high potential for clinical application in safely assessing MI caused by CAS.
