Impact of Coronary Microvascular Dysfunction on Patient-Reported Symptoms After PCI

Coronary microvascular dysfunction (CMD) has been proposed as a mechanism underlying residual angina after percutaneous coronary intervention (PCI).

The objective of the study was to investigate the impact of CMD on symptoms in patients undergoing PCI.

Patients with hemodynamically significant coronary artery disease (CAD) (fractional flow reserve ≤0.80) were included. CAD was classified as focal or diffuse using the pull back pressure gradient (PPG) (diffuse CAD defined as PPG <0.62). CMD was defined as microvascular resistance reserve <3.0. The Seattle Angina Questionnaire (SAQ) was administered at baseline and 1 year.

Among 201 patients (mean age 68.5 ± 10.1 years; 71% male), CMD was present in 75 (37.3%), with no difference between focal and diffuse CAD (41% vs 34%; P = 0.35). At baseline, CMD was associated with more severe symptoms without reaching statistical significance (SAQ summary score 64.0 ± 25.3 vs 69.6 ± 21.0; P = 0.09). At 1 year, symptoms were similar between groups (SAQ summary score 87.6 ± 16.0 vs 89.4 ± 16.4; P = 0.47). A significant interaction between PPG and microvascular resistance reserve was observed for residual angina (P for interaction = 0.015); patients with focal CAD and concomitant CMD had the highest burden of residual symptoms.

CMD is present in approximately one-third of patients undergoing PCI and occurs with similar frequency in focal and diffuse CAD. CMD alone was not associated with residual angina. However, its clinical relevance varied according to the epicardial disease pattern: in focal CAD, concomitant CMD was associated with less symptomatic improvement after PCI, whereas in diffuse CAD, residual symptoms appeared to be driven predominantly by persistent epicardial disease.