Resting Pd/Pa correlates with fractional flow reserve but not angiographic severity in calcified coronary arteries.

ABSTRACT

OBJECTIVE: Study the effect of coronary artery calcium (CAC) on resting coronary physiological indices. BACKGROUND: Prior studies found no correlation between angiographic stenosis and fractional flow reserve (FFR) in heavily calcified arteries. METHODS: Two hundred consecutive patients undergoing whole-cycle resting Pd/Pa and FFR evaluation of a single lesion of intermediate severity (40-80%) had CAC quantified based upon radiopacities at the site of the stenosis, where 0 = none or mild calcium, 1 = moderate calcium, and 2 = severe calcium. RESULTS: Mean age was 61 ± 11 years and 34% were female. The mean degree of stenosis, FFR, and resting Pd/Pa were 60 ± 12%, 0.83 ± 0.08, and 0.93 ± 0.05, respectively. Resting Pd/Pa correlated with degree of angiographic diameter stenosis (DS) as determined by quantitative coronary angiography (QCA) or visual estimation in arteries with calcium score of 0 or 1, but there was no correlation in severely calcified arteries. The diagnostic accuracy of DS ≥70% by QCA to predict hemodynamic significance was 68% with calcium scores of 0/1, but only 43% with calcium score = 2. Resting Pd/Pa was highly correlated with FFR irrespective of the degree of CAC (R2 = 0.68, p < .001) and the sensitivity of resting Pd/Pa ≤0.91 for predicting an FFR ≤0.80 was 0.67 in arteries with calcium scores of 0 or 1 and 0.69 in arteries with a calcium score of 2. CONCLUSIONS: There was no correlation between angiographic stenosis and either resting Pd/Pa or FFR in heavily calcified coronary artery lesions.