Relation between Door-to-Balloon Time and Microvascular Perfusion as Evaluated by Myocardial Blush Grade, Corrected TIMI Frame Count, and ST-segment Resolution in Treatment of Acute Myocardial Infarction

Background: The role of microvascular perfusion in relation to door-to-balloon time and mortality remains unknown. We sought to compare microvascular perfusion in patients who had undergone primary percutaneous coronary intervention with door-to-balloon time ≤90 minute versus >90 minutes.

Methods: Using myocardial blush grade (MBG), corrected TIMI frame count (CTFC), and ST-segment resolution, microvascular perfusion was assessed in 297 patients who underwent successful primary percutaneous coronary intervention between January 2007 and April 2008.

Results: Door-to-balloon time was ≤90 minutes in 199 (67%) patients and >90 minutes in 98 (33%) patients. Univariate analysis showed that door-to-treatment >90 minutes was associated with MBG 0/1 and CTFC >28. However, it was not associated with ST-segment resolution ≤70%. After adjustment for baseline confounding factors, door-to-balloon time >90 minutes was still associated with MBG 0/1 (adjusted OR 3.20, 95% CI 1.87 to 5.49, P < 0.001) and CTFC >28 (adjusted OR 6.30, 95% CI 3.56 to 11.17, P < 0.001). Thirty-day mortality was higher in patients with longer door-to-balloon time (adjusted OR 2.87, 95% CI 0.94 to 8.77, P = 0.064).

Conclusion: We found that door-to-balloon time >90 minutes, compared with ≤90 minutes, was independently associated with MBG 01/2 and CTFC >28, both suggesting microvascular obstruction. However, such association was not found in ST-segment resolution. Patients with door-to-balloon time >90 minutes also had higher 30-day mortality.