Coronary microvascular dysfunction after elective percutaneous coronary intervention: Correlation with exercise stress test results

OBJECTIVES: We assessed whether exercise stress test (EST) results are related to the presence of coronary microvascular dysfunction (CMVD) in patients undergoing elective percutaneous coronary intervention (PCI). BACKGROUND: Previous studies showed that EST is poorly reliable in predicting restenosis after PCI; some studies also showed CMVD in the territory of the treated vessel. METHODS: We studied 29 patients (age 64±6, 23 M) with stable coronary artery disease and isolated stenosis (>75%) of the left anterior descending (LAD) coronary artery, undergoing successful PCI with stent implantation. EST and assessment of coronary microvascular function were performed 24h, 3months and 6months after PCI. Coronary blood flow (CBF) response to adenosine and to cold-pressor test (CPT) was assessed in the LAD coronary artery by transthoracic Doppler echocardiography. RESULTS: Patients with ST-segment depression ≥1mm at EST performed 24h after PCI (n=11, 38%) showed a lower CBF response to adenosine compared to those with negative EST (1.65±0.4 vs. 2.11±0.4, respectively, p=0.003), whereas the difference in CBF response to CPT was not significant (1.44±0.4 vs. 1.64±0.3, respectively; p=0.11). At 3-month and 6-month follow-up a positive EST was found in 12 (41%) and 13 (44%) patients, respectively; patients with positive EST also had lower CBF response to adenosine compared to those with negative EST (3months: 1.69±0.3 vs. 2.20±0.3, respectively; 6months: 1.66±0.2 vs. 2.32±0.3, respectively; p<0.001 for both). CONCLUSIONS: Positive EST after elective successful PCI consistently reflects impairment of hyperemic CBF due to CMVD, which persists over a follow-up period of 6months.