Background: Distal protection during primary angioplasty in acute myocardial infarction (AMI) is the subject of recent controversy. The present study was designed to determine whether the distal embolic protection preserves myocardial microvascular integrity and improves clinical outcomes in patients with AMI.
Methods: A total of 116 AMI patients presenting within 12 h of onset of symptoms were enrolled at 7 angioplasty centers. They were randomly assigned to either primary angioplasty with distal protection group (DP; n=60) or angioplasty alone group (Controls; n=56).
Results: After primary angioplasty, achievement of final Thrombolysis In Myocardial Infarction (TIMI) grade 3 and TIMI Myocardial Perfusion (TMP) grade 3 were more frequent in the DP group than in the control group [58/60 (96%) vs. 43/56 (81%), p=0.016; and 39/60 (65%) vs. 20/56 (38%), p=0.001, respectively]. After primary angioplasty, the baseline and hyperemic averaged peak velocities were significantly higher (23.2+/-11.5 vs. 18.0+/-6.9 cm/s, p=0.029; and 39.2+/-16.7 vs. 30.6+/-10.8 cm/s, p=0.014, respectively) and the baseline and hyperemic microvascular resistance indices were significantly lower (4.18+/-2.22 vs. 5.34+/-2.25 mm Hg cm(-1) s, p=0.036; and 2.38+/-1.39 vs. 3.11+/-1.32 mm Hg cm(-1) s, p=0.030, respectively) in the DP group. Patients in the DP group showed more favorable phasic coronary flow pattern in diastolic deceleration time (679+/-262 vs. 519+/-289 ms, p=0.035; and 751+/-246 vs. 616+/-269 ms, p=0.035, respectively). Major adverse cardiac events at 6 months occurred with similar frequency in both groups (8.7% vs. 11.1%, p=0.400).
Conclusions: Distal protection device effectively preserves microvascular integrity during primary angioplasty in AMI. Distal protection, however, did not improve clinical outcomes.