Modifiable and unmodifiable factors associated with slow flow following rotational atherectomy

BACKGROUND: Although several groups reported the risk factors for slow flow during rotational atherectomy (RA), they did not clearly distinguish modifiable factors, such as burr-to-artery ratio from unmodifiable ones, such as lesion length. The aim of this retrospective study was to investigate the modifiable and unmodifiable factors that were associated with slow flow. METHODS: We included 513 lesions treated with RA, which were classified into a slow flow group (n = 97) and a non-slow flow group (n = 416) according to the presence or absence of slow flow just after RA. The multivariate logistic regression analysis was performed to find factors associated with slow flow. RESULTS: Slow flow was inversely associated with reference diameter [Odds ratio (OR) 0.351, 95% confidence interval (CI) 0.205–0.600, p<0.001], primary RA strategy (OR 0.224, 95% CI 0.097–0.513, p<0.001), short single run (≤15 seconds) (OR 0.458, 95% CI 0.271–0.776, p = 0.004), and systolic blood pressure (BP) ≥ 140 mmHg (OR 0.501, 95% CI 0.297–0.843, p = 0.009). Lesion length (every 5 mm increase: OR 1.193, 95% CI 1.093–1.301, p<0.001), angulation (OR 2.054, 95% CI 1.171–3.601, p = 0.012), halfway RA (OR 2.027, 95% CI 1.130–3.635, p = 0.018), initial burr-to-artery ratio (OR 1.451, 95% CI 1.212–1.737, p<0.001), and use of beta blockers (OR 1.894, 95% CI 1.004–3.573, p = 0.049) were significantly associated with slow flow. CONCLUSIONS: Slow flow was positively associated with several unmodifiable factors including lesion length and angulation, and inversely associated with reference diameter. In addition, slow flow was positively associated with several modifiable factors including initial burr-to-artery ratio and use of beta blockers, and inversely associated with primary RA strategy, short single run, and systolic blood pressure just before RA. Application of this information could help to improve RA procedures.