Effects of Thrombolytic Therapy on Distal Coronary Microvasculature: A Study Based on Coronary Pressure Measurements

The most important determinant of the suceess of thrombolytic therapy (TT) is the amount of salvaged myoeardial mass rather than aceomplished vessel pateney. It has already been shown that the lack of tissue perfusion in the faee of restored angiographie flow may oecur after thrombolysis in some patients. One of the most important prognostic determinants of myocardial viability and function after thrombolysis is the degree of destruction of distal microvaseulature (DMV). Intraeoronary pressure measurement is a new teehnique to provide quantiative and funeti onal information about the collaterals and DMV. Quantitation and assesment of funetion of DMV are possible by determination of eoronary wedge pressure (CWP), collateral flow index (CFI) and the responsiveness of DMV to hyperemic stimuli (~P) . In this study we investigated the effects of TT on DMV by quanti tative measuring of the perfusion pressure, funetion and patency of DMV in patients with myoeardial infaretion (MI). Material and method. Thirthy patients after AMI with more than 70% stenosis and thrombolysis in myoeardial infaretion (TIMI) grade II flow in infa rct related artery who underwent PTCA and/or stent implantation proeedure w i thin 1 O day s of MI w ere included in this study. Fifteen of them had reeeived TT within 6 hours of their symptom beginning. After angiography fiberoptie pressure ınonito ring guideTiirk wire (Pressure Wire - Radi) was advanced and positioned distal to stenosis. Proximal and distal pressures were recorded simultaneously under basa! and hyperemic conditions. During total occlusion with balloon, distal pressure was recorded as CWP. CFI was determined by the ratio of simultaneously measured CWP to aortic pressure. Capabil ity to increase pressure gradient (achievable t.P) or with an other word, responsiveness of DMV was assessed by substraction of resting pressure gradient from provoked (hyperemic) pressure gradient across the lesi on. Results. Mean CWP, CFI and t.P values were 27.7 ± 9.6 mmHg, 0.29 ± 0.09 and 22.3 ± 7.4 mmHg respectively in the group who had received TT (group I) and 18.2 ± 6.2 mmHg, 0.19 ± 0.07, 12.2 ± 6.8 mmHg in the group without TT (group II). Mean values of CWP, CFI and t.P were s ignificantly higher in the group I. The differences of these mean values were statistically significant (p<0.01, pKeywords: coronary pressure, microcirculation, thrombolytic therapy