Evaluation of mid vs distal left anterior descending artery measures in coronary physiology assessment.

Background: Angina with no obstructive coronary artery disease (ANOCA) occurs in approximately 40 % of patients who undergo diagnostic coronary angiography for symptoms of angina. Coronary physiology assessment (CPA) is a guideline proven method to assess and diagnose these patients for an effective treatment strategy. There is currently no data regarding optimal wire or sensor position for CPA using bolus coronary thermodilution.

Methods: We reviewed CPA data and baseline demographics in a cohort of patients who underwent CPA for ANOCA. We evaluated coronary flow reserve (CFR) and index of microcirculatory resistance (IMR) in patients whereby maximal hyperemia was obtained in the middle portion (4-6 cm) of the left anterior descending artery (LAD) and the distal 2/3 of the LAD using linear regression, Paired t-test, and Bland-Altman analysis.

Results: We assessed 42 patients with a median age of 60.5 [50,67] and 72 % female. Median CFR in the mid-LAD was 3.55 [2.54, 4.58] and 2.71 [2.0,3.88; p = 0.01*] in the distal segment. Median IMR in the mid-LAD was 16.41 mmHg*s [10.60, 22.07] and 22.27 mmHg*s [14.79,37.0] in the distal segment (p = 0.01*). Average distal pressures (Pd) were 77.14 mmHg in the mid and 75.31 mmHg in the distal LAD (p = 0.57) with differing resting (0.75 s vs 0.97 s, p = 0.01*) and hyperemic (0.25 vs 0.40, p = 0.003*) transit times in the mid vs distal vessel, respectively.

Conclusions: Here we demonstrate that CPA outcomes including CFR and IMR values are dependent upon wire positioning with deeper wire position resulting in lower CFR and higher IMR values.