The accuracy of deceleration time of diastolic coronary flow measured by transthoracic echocardiography in predicting long-term left ventricular infarct size and function after reperfused myocardial infarction.

AIMS: Assessment of microvascular function after reperfused acute myocardial infarction (AMI) provides important insights for myocardial reperfusion and facilitates prediction of long-term left ventricular (LV) function and clinical outcome. In this study, we examined microvascular integrity 48 h after successful primary percutaneous coronary intervention (PCI) and compared predictive accuracy of the intracoronary pressure-wire- and transthoracic Doppler echocardiography-based parameters in the estimation of long-term LV infarct size and function. METHODS AND RESULTS: The study group consisted of 30 anterior AMI patients who were treated successfully with primary PCI. Two days after primary PCI, microvascular integrity was evaluated. Coronary flow reserve (CFR), collateral flow index (CFIp), coronary wedge pressure (CWP), and index of microvascular resistance (IMR) were determined using intracoronary pressure wire. Deceleration time of coronary diastolic flow (DDT) was measured using transthoracic echocardiography. At 6 months, coronary angiography, echocardiography, and infarct size measurement were performed. Area under the curve, sensitivity, and specificity of the indices of microvascular perfusion in the prediction of late-term infarct size were as follows: IMR (0.68 ± 0.15, 69%, 60%), CFR (0.67 ± 0.10, 66%, 59%), CWP (0.69 ± 0.12, 70%, 72%), CFIp (0.64 ± 0.10, 65%, 78%), and DDT (0.68 ± 0.16, 69%, 79%). All of the microvascular perfusion indices, which have been used in this study, had comparable sensitivity and specificity in the prediction of long-term ejection fraction. There were no significant differences between areas under the curve of microvascular perfusion indices in the prediction of long-term infarct size and ejection fraction. CONCLUSION: As a non-invasive parameter, DDT was found to be as accurate as the invasive parameters of microvascular function in estimating long-term infarct size and LV function. Thus, simply measuring DDT in the reperfused infarct-related artery might provide useful and reliable estimate for early risk stratification.

Relationship between microvascular resistance and perfusion in patients with reperfused acute myocardial infarction.

UNLABELLED: Despite its prognostic importance, accurate assessment of microvascular perfusion in patients with ST elevation acute myocardial infarction (STEMI) is difficult. As a new tool, the index of microvascular resistance (IMR) measurement provides us a new opportunity for interrogating microvascular condition after STEMI. In this study, we measured IMR in infarct-related artery (IRA) and explored its relation with other indices which have been suggested to evaluate microvascular perfusion in patients with reperfused STEMI. METHODS: Forty-two patients with STEMI treated successfully with primary percutaneous coronary intervention (pPCI) were prospectively included. After 48 hours following pPCI, patients were recatheterized and IMR, coronary flow reserve (CFR), systolic and mean coronary wedge pressures (CWPs and CWPm) pressure-derived collateral flow index (CFIp) were measured in IRA by using intracoronary pressure-temperature sensor tipped guide wire. Myocardial blush grade was assessed from the second angiogram. Coronary flow velocity pattern (diastolic deceleration time: DDT) was examined with transthoracic echocardiography 48 hours after pPCI. Percentage of ST-segment recovery was calculated from surface ECG (STR%). RESULTS: IMR well correlated with CWPs (r = 0.70, P < 0.001), CWPm (r = 0.59, P < 0.001), CFIp (r = 0.65, P < 0.001), CFR (r =-0.50, P = 0.001), and DDT (r =-0.59, P = 0.001). Correlations of IMR to non/semiinvasive indices like myocardial blush grades (MBG) (r =-0.42, P = 0.007) and STR (r =-0.37, P = 0.024) are somewhat weaker. CONCLUSION: Given its simplicity of measurement, independence from the presence of an epicardial stenosis, and good correlation with all measures of microvascular obstruction used in this study, IMR may prove to be a valuable modality for evaluating the microcirculation.

Intracoronary streptokinase after primary percutaneous coronary intervention.

BACKGROUND: Microvascular perfusion is often impaired after primary percutaneous coronary intervention (PCI). We proposed that in situ thrombosis might contribute to poor myocardial perfusion in this setting. To test this hypothesis, we evaluated the effect of low-dose intracoronary streptokinase administered immediately after primary PCI. METHODS: Forty-one patients undergoing primary PCI were randomly assigned to receive intracoronary streptokinase (250 kU) or no additional therapy. Two days later, cardiac catheterization was repeated, and coronary hemodynamic end points were measured with the use of a guidewire tipped with pressure and temperature sensors. In patients with anterior myocardial infarction, the deceleration time of coronary diastolic flow was measured with transthoracic echocardiography. At 6 months, angiography, echocardiography, and technetium-99m single-photon-emission computed tomography were performed. RESULTS: Two days after PCI, all measures of microvascular function (means +/-SD) were significantly better in the streptokinase group than in the control group, including coronary flow reserve (2.01+/-0.57 vs. 1.39+/-0.31), the index of microvascular resistance (16.29+/-5.06 U vs. 32.49+/-11.04 U), the collateral-flow index (0.08+/-0.05 vs. 0.17+/-0.07), mean coronary wedge pressure (10.81+/-5.46 mm Hg vs. 17.20+/-7.93 mm Hg), systolic coronary wedge pressure (18.24+/-6.07 mm Hg vs. 33.80+/-11.00 mm Hg), and diastolic deceleration time (828+/-258 msec vs. 360+/-292 msec). The administration of intracoronary streptokinase was also associated with a significantly lower corrected Thrombolysis in Myocardial Infarction frame count (the number of cine frames required for dye to travel from the ostium of a coronary artery to a standardized distal coronary landmark) at 2 days. At 6 months, however, there was no evidence of a difference between the two study groups in left ventricular size or function. CONCLUSIONS: In our pilot trial, the administration of low-dose intracoronary streptokinase immediately after primary PCI improved myocardial reperfusion but not long-term left ventricular size or function. These findings require clarification in a larger trial. (ClinicalTrials.gov number, NCT00302419.)

Association of haematological indices with the degree of microvascular injury in patients with acute anterior wall myocardial infarction treated with primary percutaneous coronary intervention.

BACKGROUND: In acute myocardial infarction (AMI), increased neutrophil count has been associated with more severe coronary artery disease and larger infarct size. Increased mean platelet volume (MPV) is also associated with poor clinical outcome and impaired angiographic reperfusion in patients with AMI. However, the associations of neutrophil count and MPV with the indices of tissue level reperfusion were not fully elucidated. AIM: To elucidate the relationship between baseline neutrophil count and MPV on presentation and microvascular injury in patients with anterior AMI treated with primary percutaneous coronary intervention (pPCI). METHODS: 41 patients with anterior wall AMI treated successfully with pPCI were included. The leucocyte count, neutrophil count and MPV were obtained on admission, and the percentage of neutrophils was calculated. After PCI thrombolysis in myocardial infarction, grade 3 flow was established in all patients. The coronary flow velocity pattern (diastolic deceleration time (DDT)) was examined with transthoracic echocardiography and measured intracoronary pressures with fibreoptic pressure-temperature sensor-tipped guidewire in the left anterior descending artery within 48 h after pPCI. Thermodilution-derived coronary flow reserve (CFR) was calculated. Index of microvascular resistance (IMR) was defined as simultaneously measured distal coronary pressure divided by the inverse of the thermodilution-derived hyperaemic mean transit time. Subsequently, a short compliant balloon was placed in the stented segment and inflated to measure coronary wedge pressure (CWP). RESULTS: Higher neutrophil counts were strongly associated with higher IMR (r = 0.86, p<0.001), lower CFR (r = -0.60, p<0.001), shorter DDT (r = -0.73, p<0.001) and higher CWP (r = 0.73, p<0.001). Likewise, there were significant correlations among the percentage of neutrophils and CFR (r = -0.34, p = 0.02), IMR (r = 0.46, p = 0.002), DDT (r = -0.36, p = 0.01) and CWP (r = 0.49, p = 0.001). Relationships among leucocyte count and IMR (r = 0.38, p = 0.01), CFR (r = -0.33, p = 0.03), DDT (r = -0.36, p = 0.01) and CWP (r = 0.32, p = 0.026) were slightly significant. Higher neutrophil count remained independently associated with indices of microvascular perfusion in multivariable models controlling for age, smoking habits and time to treatment. Also, higher MPV on admission was strongly associated with higher IMR (r = 0.89, p<0.001), steeper DDT (r = -0.64, p<0.001), lower CFR (r = -0.43, p = 0.004) and higher CWP (r = 0.77, p<0.001). CONCLUSION: Absolute and relative neutrophilia and higher MPV on admission were independently associated with impaired microvascular perfusion in patients with anterior AMI treated with pPCI. It is possible that neutrophilia and high MPV are simple surrogate markers of worse microvascular injury in patients with AMI.

A potential evidence to explain the reason behind the devastating prognosis of coronary artery disease in uraemic patients: renal insufficiency is associated with poor coronary collateral vessel development.

The potential of individuals to develop coronary collateral circulation is often neglected but is of potential major importance in myocardial vulnerability. Likewise, the effect of chronic kidney disease (CKD) on collateral vessel development is not known. The purpose of this study was to evaluate the effect of CKD on collateral development in patients with advanced coronary artery disease. A total of 171 uraemic patients (serum creatinine > or = 1.5 mg/dl, creatinine clearance < 80 mL)/min) who underwent coronary angiography were evaluated in this study. A total of 134 patients met the criteria for the uraemic group and 134 consecutive non-uraemic patients who constituted the control group. The collateral score (CS) was graded according to the Rentrop classification and the collateral score was calculated by summing the Rentrop numbers of every patient. Collateral vessels have also been categorized according to their anatomic locations and collateral connection grades (CC). CC2 collaterals were observed less frequently in the uraemic patients than in the control subjects (11% versus 26%, p=0.03) and CC0 more frequently (31% versus 22%, p<0.05). Epicardial pathway was detected more frequently in the control subjects than in the uraemic patients (31% versus 12%, p=0.03) and septal pathway less frequently (37% versus 54%). There was a significant negative correlation between CS and creatinine (r=-0.68, p<0.01). The mean CS in the uraemic group was significantly lower than the non-uraemic group (1.29+/-0.88 versus 2.18+/-1.3, p<0.001). These results altogether showed that besides the quantity, quality (functional, haemodynamic and anatomic features) of the uraemic collaterals and a network that they constitute is also impaired and different from the collaterals of the patient with normal renal function.

Pressure-derived collateral flow index: a strong predictor of late left ventricular remodeling after thrombolysis for acute myocardial infarction.

OBJECTIVE: Despite proved efficacy of pressure-derived collateral flow index in determining microvascular dysfunction in patients with acute myocardial infarction, its role in prediction of left ventricular remodeling at long term has yet to be demonstrated. In this study, we investigated the relationship between quantitatively assessed microvascular dysfunction by using intracoronary pressure wire and late left ventricular remodeling. PATIENTS AND METHODS: The study population consisted of 28 patients with first acute myocardial infarction. They were treated with fibrinolytic therapy. The inclusion criteria were thrombolysis in myocardial infarction grade II-III flow in infarct-related artery and all destined for stent implantation. Cardiac catheterization and stent implantation were performed in mean of 3.3 days after acute myocardial infarction. During the stent implantation procedure, the pressure-derived collateral flow index was measured by using intracoronary pressure wire. Control angiograms were performed at 6+/-2 months. Echocardiographic left ventricular volume indexes were measured at discharge, at 6 months and at 1 year. Changes in left ventricular volumes from baseline to 1 year were followed. RESULTS: Left ventricular end-diastolic volume index at 1 year correlated significantly with the pressure-derived collateral flow index (r=0.69, P<0.01). A significant correlation was also observed between the change in left ventricular end-diastolic volume index from baseline to 1 year and the pressure-derived collateral flow index (r=0.65, P<0.01). The most important predictor of 1-year left ventricular remodeling was the pressure-derived collateral flow index (P<0.0001), and collateral circulation (P=0.03). CONCLUSION: The pressure-derived collateral flow index is a powerful independent predictor of 1-year left ventricular dilatation. Given its simplicity of measurement, and correlation with microvascular obstruction and left ventricular outcome at long term, the pressure-derived collateral flow index may provide useful and valuable estimates of clinical outcomes after acute myocardial infarction.