Abstract 2798: Clinical Implications of Distal Embolization during Coronary Interventional Procedures in Patients With Acute Myocardial Infarction: Impact on Capillary Integrity
Distal embolization to small arteries and arterioles is one of the major complications of percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI), and we quantify embolic particles from the number of high-intensity transient signals (HITS) with the Doppler guidewire (DGW). This study was performed to count the number of HITS in relation to PCI procedure, and to investigate the relation of embolization to resistance vessels to capillary integrity in the infarct zone in patients with AMI.
METHODS: We studied 26 patients with first AMI who underwent successful PCI within 6 h after onset. We performed 1st and 2nd balloon angioplasty with continuous monitoring of coronary blood flow velocity with the DGW, followed by stenting and post high-pressure dilatation (20 atm). From 10 to 15 minutes after PCI, we evaluated TIMI flow grade and myocardial perfusion at the capillary level with myocardial contrast echocardiography (MCE). Left ventriculography was performed to measure regional wall motion (RWM, SD/chord) on days -1 and 21.
RESULTS: HITS were detected throughout the PCI procedure in 24 of 26 patients, with the highest number of HITS after stenting (18±19). Finally, TIMI-3 flow and TIMI-2 flow were achieved in 22 and 4 patients, respectively (LAD: n=1; RCA: n=3). All these latter 4 patients showed TIMI-3 flow after balloon angioplasty, but showed reduction of coronary flow after stenting, and 3 exhibited transient complete A-V block. The number of HITS was greater in patients with TIMI-2 flow than in those with TIMI-3 flow (64±27 vs. 18±20, P<0.01). However, all patients showed good contrast enhancement in the infarct zone, implying preserved capillary integrity. There was no significant correlation between the total number of HITS and the magnitude of improvement in RWM (r=0.26, P=0.25).
Distal embolization is common and the majority occur after stenting in patients with AMI.
Coronary flow reduces only when the number of HITS is large, resulting in transient hemodynamic deterioration, but the integrity of capillaries can be preserved.
Increases in number of emboli are not necessarily associated with left ventricular dysfunction in this range.