Background: Coronary flow reserve (CFR) has important clinical implications for the evaluation of coronary circulation including Kawasaki disease (KD). Pharmacological vasodilation is generally used to induce hyperemia for the assessment of CFR; however, exercise test provides more physiological stress.
Objectives: This study sought to assess CFR during exercise in patients after KD with regressed coronary arterial lesions (CALs) by transthoracic echocardiography (TTE).
Methods: Twenty KD patients were studied, comprising 8 patients with regressed CALs in the left anterior descending coronary artery (LAD) and 12 patients without CALs (median ages; 10 and 9 years, respectively). Fourteen age-matched healthy subjects were also studied as controls. We obtained peak diastolic coronary flow velocity (CFV) of the LAD by pulsed-Doppler TTE at rest and at submaximal exercise on supine ergometer. CFR was calculated as the ratio of exercise to rest CFVs.
Results: The CFV measurements were obtained in all the subjects. There was no significant difference in the CFVs among the patients with regressed CALs, those without CALs and the controls (30 ± 7 vs. 31 ± 10 vs. 28 ± 8 cm/s, respectively). The CFVs increased during exercise in the patients without CALs and the controls (51 ± 11 and 49 ± 10 cm/s, respectively, both p <0.05). In consequence, the CFR was lower in the patients with regressed CALs compared with those without CALs and the controls (1.3 ± 0.2 vs. 1.7 ± 0.2 and 1.7 ± 0.2, respectively, p <0.05).
Conclusions: Exercise test demonstrated impaired CFR in KD patients with regressed CALs. It suggests that these patients have risk of future myocardial ischemic events.