Abstract 15477: The Impact of Thermodilution-Derived Coronary Blood Flow Pattern on Severity of Microcirculatory Damage and Mid-Term Clinical Outcomes in Patients with ST-Segment Elevation Myocardial Infarction
Background: Despite a sufficient coronary flow after percutaneous coronary intervention (PCI) for patients with ST-segment elevation myocardial infarction (STEMI), some patients have a poor outcome because of microcirculatory damage. Recently, coronary blood flow can be assessed by the thermodilution technique using the pressure sensor/thermistor-tipped guidewire. This study sought to evaluate whether the thermodilution-derived blood flow parameters immediately after primary PCI predict early microvascular damage and mid-term outcomes for STEMI patients.
Methods: Using the pressure sensor/thermistor-tipped guidewire, we measured the index of microcirculatory resistance (IMR) at maximum hyperemia and assessed coronary blood flow pattern with the thermodilution technique after successful PCI in 48 STEMI patients. Coronary blood flow pattern was classified into 3 groups according to the shape of thrmodilution curve: monomodal with sharp (n=17), monomodal with dull (n=25), and biomodal shape (n=6). All patients had cardiac magnetic resonance (CMR) scans and an echocardiogram within 2week. Microvascular obstruction (MVO) was defined as a dark core of hypoenhancement within the area of hyperenhanced infarct tissue on CMR. Wall motion score index (WMSI) was calculated using 16-segmental model.
Results: The IMR values were significantly higher both in monomodal with dull and biomodal shapes than in monomodal with sharp (56±39 and 79±48 vs. 16±6U, p<0.01). Biomodal shape was associated with higher WMSI (2.00, 1.66, and 1.59, p<0.05) and higher incidence of MVO (83, 72, and 42%, p<0.01). Patients with biomodal shape had a higher risk of death and/or heart failure (HF) admission at 1 year (67, 4.0, 5.8%, p<0.01). Multivariate analysis revealed that biomodal shape of the thermodilution curve was the only independent predictor of 1-year death and HF admission (p<0.05).
Conclusions: A biomodal shape of the thermodilution curve, which may indicate myocardial edema and consequent extrinsic compression of the capillary network, is associated with microcirculatory damage and poor mid-term clinical outcomes rather than the IMR value. This easily assessable coronary flow pattern is useful in clinical risk stratification for patients with STEMI.
- © 2011 by American Heart Association, Inc.