Influence of gradually increased slow balloon inflation on restenosis after coronary angioplasty

Balloon inflation during coronary angioplasty results in shear stress-induced vessel wall injury with development of restenosis. This randomized trial compared the impact of two different balloon inflation strategies (slow versus fast) on restenosis after coronary angioplasty.

Two hundred seven patients were randomized to undergo either fast or gradually increased slow inflation after successful placement of the balloon catheter inside the target lesion. One hundred six underwent fast, and 101 underwent gradually increased slow balloon inflation. Coronary angiograms were quantitatively analyzed before angioplasty, after angioplasty, and at follow-up 5.9+/-1.6 months after the initial procedure.

Both groups had an identical primary success rate (98.1% vs 98%; p = 0.96) and a similar minimal luminal diameter before (0.49+/-0.26 mm vs 0.48+/-0.22 mm; p = 0.8) and after (2.22+/-0.97 mm vs 2.26+/-0.66 mm; p = 0.7) angioplasty. Slow balloon inflation did not reduce late luminal loss (0.58+/-0.77 mm vs 0.74+/-0.87 mm; p = 0.2), net gain (1.33+/-0.84 mm vs 1.19+/-0.81 mm; p = 0.3), or minimal luminal diameter at follow-up (1.80+/-0.97 mm vs 1.72+/-1.0 mm; p = 0.6) significantly. Restenosis, defined as >50% diameter stenosis at follow-up, occurred in 24% in the slow inflation group versus 36% in the fast inflation group (p = 0.09). Clinical events during 6-month follow-up were similar in both groups (repeat angioplasty, fast 5.6%, slow 4.8%, p = 0.8; nonfatal myocardial infarction, fast 2.2%, slow 1.2%, p = 0.6; death, fast 1.1%, slow 0%, p = 0.3).

The present randomized trial of two different balloon inflation strategies shows no statistically significant difference in net gain, minimal luminal diameter, or restenosis after coronary angioplasty. The difference in net gain, minimal luminal diameter, and restenosis rate were not statistically significant, but may represent a trend toward a reduction of smooth muscle cell proliferation and intimal hyperplasia induced by careful dilation of the stenotic lesion with gradually increased slow balloon inflation and reduction of shear stress-related vessel wall injury.