Ananth M. Prasan

Elevated circulating levels of matrix metalloproteinase‐9 and ‐2 in patients with symptomatic coronary artery disease

Abstract

Grade 3 ischemia on the admission electrocardiogram is associated with severe microvascular injury on cardiac magnetic resonance imaging after ST elevation myocardial infarction

BACKGROUND Grade 3 ischemia during ST elevation myocardial infarction (STEMI) is defined as ST elevation with distortion of the terminal portion of the QRS on electrocardiogram (ECG). The aim of this study was to evaluate the effect of ischemic grade on cardiac magnetic resonance (CMR) imaging infarct characteristics such as infarct size, microvascular obstruction (MVO), intramyocardial hemorrhage (IMH), and myocardial salvage. METHODS Patients with STEMI treated with primary percutaneous coronary intervention had a 12-lead ECG on presentation for analysis of ischemic grade. Gadolinium-enhanced CMR imaging was performed within 7 days to assess infarct size, MVO, IMH, and myocardial salvage. RESULTS Of the 37 patients enrolled in the study, grade 3 ischemia was present in 32%. Those with grade 3 ischemia had higher peak troponin I levels (P = .013), more MVO (P < .001), more IMH (P < .001), larger infarct size (P = .025), and less myocardial salvage (P = .012). Regression analysis found that grade 3 ischemia, infarct size, and peak troponin I level were significantly associated with MVO and IMH. CONCLUSION Grade 3 ischemia on the admission ECG during STEMI is closely associated with the development of severe microvascular damage on CMR imaging.

Disassembly of a rotablator: getting out of a trap.

The rotablator burr rarely becomes trapped within calcified lesions. Manual traction can be ineffective and dangerous. We report a case that illustrates a novel technique involving use of a percutaneous snare in conjunction with partial disassembly of the rotablator device to remove a trapped burr without need for open surgical intervention. Cathet Cardiovasc Intervent 2003;59:463–465.

Dynamic Changes in ST Segment Resolution After Myocardial Infarction and the Association with Microvascular Injury on Cardiac Magnetic Resonance Imaging

BACKGROUND persistent ST elevation after reperfused ST elevation myocardial infarction (STEMI) is believed to be related to poor microvascular perfusion. Cardiac magnetic resonance imaging (CMR) can evaluate microvascular obstruction (MVO) and intramyocardial haemorrhage (IMH) both of which represent severe microvascular damage, have independent prognostic value and are dynamic and evolving over the first 48hours after reperfusion. The aim of this study was to assess whether the development of MVO or IMH has an impact upon ST segment resolution. METHODS patients undergoing primary percutaneous coronary intervention (PCI) for STEMI had serial 12 lead electrocardiograms (ECG) from one hour after PCI until discharge. Persistent single lead maximal residual ST elevation (maxSTE) at each time point was calculated. ST segment deterioration (re-elevation) was calculated on each ECG until discharge compared with one hour post PCI ECG. CMR was performed within seven days post infarct utilising T2 weighted imaging to evaluate culprit artery area at risk (AAR) and IMH. Gadolinium delayed enhancement CMR quantified infarct size and MVO. RESULTS in the 41 patients studied 58% had MVO and 41% had IMH. ST segment deterioration was more common in those with MVO or IMH (p=0.03 and p=0.008 respectively). MaxSTE was higher at each time point after PCI in those with MVO but only became statistically significant after 24hours. The measurement of maxSTE at 48 or 72hours after revascularisation provided the best correlation with the combination of infarct size, AAR, MVO and intramyocardial haemorrhage. CONCLUSION microvascular injury as defined on CMR is associated with dynamic changes and persistence of ST segment elevation in the first 72hours after reperfusion.

Serum Thromboxane B2 Compared to Five Other Platelet Function Tests for the Evaluation of Aspirin Effect in Stable Cardiovascular Disease

BACKGROUND To assess the role of serum thromboxane B(2) (TXB(2)) measurements and the correlation between platelet function studies, in patients with stable cardiovascular disease on aspirin or clopidogrel. METHODS 76 patients (47 on aspirin, 16 clopidogrel, 13 both) underwent assessment of TXB(2), whole blood aggregometry (WBA) after stimulation with (i) arachidonic acid (0.5mM), (ii) ADP (5 microM), (iii) collagen (1 and 5 microg/ml), PFA-100, and Cone and Plate Analyzer. Clopidogrel patients were additionally assessed by the VerifyNow System. RESULTS TXB(2) values ranged between 0.2 and 56.2 ng/ml, with significant separation between those taking aspirin, clopidogrel and controls (0.45 ng/ml vs 6.85 ng/ml vs 12.97 ng/ml, p<0.001). There was moderate correlation between WBA-AA and TXB(2) (r=0.487, p<0.001), PFA-100((R)) (r=0.599, p<0.001), WBA-Col1 (r=0.424, p<0.001), WBA-Col1:5 (r=0.417, p<0.001), and between TXB(2) and PFA-100((R)) (r=0.509, p<0.001). The prevalence of aspirin non-responders for WBA-AA, TXB(2), PFA-100((R)), CPA and Coll1:5 was 13.1%, 8.2%, 14.8%, 9.7% and 16.4% respectively. Individual patients were not consistently classified as aspirin non-responders in all tests. Those with inadequate aspirin response on > or =3 tests had higher TXB(2) levels (mean 1.57+/-1.66, range 0.553-4.45 vs mean 0.45+/-0.18, range 0.23-1.50) (p=0.001). Clopidogrel suppressed TXB(2) (p=0.02), WBA-AA (p<0.001), WBA-Col1 (p=0.012) and WBA-ADP (p<0.001) compared to controls. TXB(2) in patients ingesting fish oil tablets was lower compared to those without (0.4 ng/ml vs 0.52 ng/ml, p=0.004). Obesity was associated with higher TXB(2) values (0.61 vs 0.41, p=0.01). CONCLUSION Serum TXB(2) measurements are a direct measure of the pharmacological effect of aspirin, are easily performed and correlate with other measures of platelet function. Serum TXB(2) measurements could be a useful sole measure of aspirin non-response, and may be even more predictive when performed in tandem with a global measure of platelet function. Aspirin and clopidogrel both suppressed several platelet pathways.

Duration of ischaemia determines matrix metalloproteinase-2 activation in the reperfused rabbit heart

It has been hypothesised that activation of matrix metalloproteinase‐2 (MMP‐2) contributes to reversible myocardial dysfunction (stunning) following short‐term ischaemia and reperfusion. Gelatin zymography was used to measure release of both pro‐MMP‐2 (72 kDa) and MMP‐2 (62 kDa), into the coronary effluent from isolated, perfused rabbit hearts during 90 min aerobic perfusion (control), or low‐flow ischaemia (15 or 60 min at 1 mL/min), followed by 60 min reperfusion. In controls, pro‐MMP‐2 was detected in the coronary effluent throughout the first 30 min of aerobic perfusion, but MMP‐2 was not detected. In contrast, MMP‐2 was detected in the coronary effluent during reperfusion after both 15 and 60 min ischaemia. However, while left ventricular systolic function was impaired after both 15 min and 60 min ischaemia, a significant increase in the release of MMP‐2 was only detected in hearts following 60 min ischaemia. The dissociation between mechanical function and MMP‐2 levels suggest that MMP‐2 does not contribute to myocardial stunning in this model, but may contribute to myocardial dysfunction following prolonged ischaemia.

Radiation Exposure During Elective Coronary Angioplasty: The Effect of Flat-Panel Detection

BACKGROUND Coronary angiography and angioplasty have to date been performed using digital angiography and fluoroscopic systems which incorporate an image intensifier (II). More recently flat-panel (FP) detectors have been introduced which are thought to improve spatial resolution. However, there is limited data on the effect of flat-panel detection on radiation exposure. We sought to determine the impact of flat-panel on cumulative radiation exposure in patients undergoing elective coronary angioplasty at our institution. METHODS Patients who underwent elective coronary angioplasty in the six months prior to and following upgrade of our Toshiba catheterisation laboratory from image intensifier to flat-panel were included. Demographic and radiation data were collected prospectively and the same five operators performed interventions during the 12-month period. Radiation data was obtained from the dose-area product meter intrinsic to the fluoroscopy system. RESULTS One hundred and thirty seven patients underwent elective angioplasty over the 12-month period (68 II, 69 FP). Cumulative radiation exposure was increased in flat-panel cases (99, 129 Gy cm(2) versus 71, 77 Gy cm(2), p=0.001). This increase was independent of patient weight (78+/-15 kg versus 78+/-17 kg, p=NS), screening time (19+/-12 min versus 18+/-13 min, p=NS) and total number of digital acquisitions (1475, 820 versus 1668, 1365, p=NS). The total amount of contrast dye did not differ between flat-panel and image intensifier cases (195+/-76 ml versus 194+/-79 ml, p=NS). CONCLUSIONS Adoption of flat-panel detector technology increases radiation exposure. This may have important safety implications for catheterisation laboratory staff and patients undergoing multiple interventional procedures.

Sonovue improves endocardial border detection and variability in assessing wall motion score and ejection fraction during stress echocardiography

Background Stress echocardiography is useful for assessing patients with coronary artery disease unable to undergo formal exercise testing. Considerable skill is required to avoid large intra- and inter-observer variability due to poor endocardial definition. Intravenous ultrasound contrast agents are now available which may improve this variability.Aim To study intravenous Sonovue in assessing wall motion score and ejection fraction (EF) during stress echocardiography.Methods Thirty-eight patients undergoing arbutamine stress echocardiography for known or suspected coronary artery disease were studied. Echocardiographic analysis of wall motion score index, endocardial border detection (EBD) and EF was performed at rest and at peak stress before and after intravenous injection of Sonovue, by experienced and inexperienced observers.Results All three observers noted an improvement in endocardial border definition following Sonovue (p=<0.001). At baseline, there was a significant difference in wall motion score index between experienced and inexperienced observers at rest (p=0.01) and at peak stress (p=0.001). Following Sonovue administration this was no longer significant (p=0.07, p=0.114). Intra-observer variability of end diastolic, end systolic volumes (ESV) and EF improved following contrast (p<0.05) at rest and during stress.Conclusion Sonovue significantly improved EBD and reduced intra-observer variability of EF at rest and during peak arbutamine infusion.

Real-time colour pictorial radiation monitoring during coronary angiography: effect on patient peak skin and total dose during coronary angiography.

AIMS The aim of this study was to evaluate whether a real-time (RT) colour pictorial radiation dose monitoring system reduces patient skin and total radiation dose during coronary angiography and intervention. METHODS AND RESULTS Patient demographics, procedural variables and radiation parameters were recorded before and after institution of the RT skin dose recording system. Peak skin dose as well as traditionally available measures of procedural radiation dose were compared. A total of 1,077 consecutive patients underwent coronary angiography, of whom 460 also had PCI. Institution of the RT skin dose recording system resulted in a 22% reduction in peak skin dose after accounting for confounding variables. Radiation dose reduction was most pronounced in those having PCI but was also seen over a range of subgroups including those with prior coronary artery bypass surgery, high BMI, and with radial arterial access. This was associated with a significant reduction in the number of patients placed at risk of skin damage. Similar reductions in parameters reflective of total radiation dose were also demonstrated after institution of RT radiation monitoring. CONCLUSIONS Institution of an RT skin dose recording reduced patient peak skin and total radiation dose during coronary angiography and intervention. Consideration should be given to widespread adoption of this technology.

New bifurcation stenting technique: Shunt stenting

The optimal treatment of bifurcation lesions remains controversial. We describe a new technique we term shunt stenting. This technique incorporates both the new technology of drug‐eluting stents and a novel procedure for optimizing the ostial side branch stent positioning. To date, early angiographic and clinical follow‐up have been encouraging. Catheter Cardiovasc Interv 2004;63:474–481.