Illusion of reperfusion. Does anyone achieve optimal reperfusion during acute myocardial infarction?

Illusion of revascularization: does anyone achieve optimal revascularization during percutaneous coronary intervention?

This Perspective article is a form of 'pastiche', inspired by the 1993 review by Lincoff and Topol entitled 'Illusion of reperfusion', and explores how their concept continues to apply to percutaneous revascularization in patients with coronary artery disease and ischaemia. Just as Lincoff and Topol argued that reperfusion of acute myocardial infarction was facing unresolved obstacles that hampered clinical success in 1993, we propose that challenging issues are similarly jeopardizing the potential benefits of stent-based angioplasty today. By analysing the appropriateness and efficacy of percutaneous coronary intervention (PCI), we emphasize the limitations of relying solely on visual angiographic guidance, which frequently leads to inappropriate stenting and overtreatment in up to one-third of patients and the associated increased risk of periprocedural myocardial infarction. The lack of optimal revascularization observed in half of patients undergoing PCI confers risks such as suboptimal physiology after PCI, residual angina and long-term stent-related events, leaving an estimated 76% of patients with an 'illusion of revascularization'. These outcomes highlight the need to refine our diagnostic tools by integrating physiological assessments with targeted intracoronary imaging and emerging strategies, such as co-registration systems and angiography-based computational methods enhanced by artificial intelligence, to achieve optimal revascularization outcomes.

[Proposal for initial management of uncomplicated ST elevation myocardial infarction in centers without percutaneous coronary intervention capacity in Peru]

ST-segment elevation myocardial infarction (STEMI) is a clinical entity whose adequate treatment will depend on its prompt recognition, accurate diagnosis, and management in reperfusion networks. The first contact with these patients is generally done in centers without reperfusion capacity, attended by non-cardiologist doctors, and in centers far from hospitals with greater resolution capacity, something that is well known in our country. This manuscript proposes a strategy for the diagnosis and treatment of STEMI in centers without percutaneous coronary intervention capacity of the public health system in Peru, emphasizing not losing sight of electrocardiographic patterns compatible with coronary artery occlusion, adequate fibrinolysis and management of its complications, the treatment of infarction in special populations and highlighting the importance of the pharmacoinvasive strategy as the main form of reperfusion treatment in our country.

IntraCoronary Artery Retrograde Thrombolysis vs. Thrombus Aspiration in ST-Segment Elevation Myocardial Infarction: Study Protocol for a Randomized Controlled Trial

Background

Type 2 diabetes (T2DM) is a major risk factor for myocardial infarction. Thrombus aspiration was considered a good way to deal with coronary thrombus in the treatment of acute myocardial infarction. However, recent studies have found that routine thrombus aspiration is not beneficial. This study is designed to investigate whether intracoronary artery retrograde thrombolysis (ICART) is more effective than thrombus aspiration or percutaneous transluminal coronary angioplasty (PTCA) in improving myocardial perfusion in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI).

Methods/Design

IntraCoronary Artery Retrograde Thrombolysis (ICART) vs. thrombus aspiration or PTCA in STEMI trial is a single-center, prospective, randomized open-label trial with blinded evaluation of endpoints. A total of 286 patients with STEMI undergoing PPCI are randomly assigned to two groups: ICART and thrombus aspiration or PTCA. The primary endpoint is the incidence of >70% ST-segment elevation resolution. Secondary outcomes include distal embolization, myocardial blush grade, thrombolysis in myocardial infarction (TIMI) flow grade, and in-hospital bleeding.

Discussion

The ICART trial is the first randomized clinical trial (RCT) to date to verify the effect of ICART vs. thrombus aspiration or PTCA on myocardial perfusion in patients with STEMI undergoing PPCI.

Clinical Trial Registration

[https://www.chictr.org.cn/], identifier [ChiCTR1900023849].

A Novel Bi-Functional Fibrinolytic Enzyme with Anticoagulant and Thrombolytic Activities from a Marine-Derived Fungus Aspergillus versicolor ZLH-1

Fibrinolytic enzymes are important components in the treatment of thrombosis-associated disorders. A new bi-functional fibrinolytic enzyme, versiase, was identified from a marine-derived fungus Aspergillus versicolor ZLH-1. The enzyme was isolated from the fungal culture through precipitation with ammonium sulfate at 90% saturation. Additionally, it was further purified by DEAE-based ion-exchange chromatography, with a recovery of 20.4%. The fibrinolytic enzyme presented as one band on both SDS-PAGE and fibrin-zymogram, with a molecular mass of 37.3 kDa. It was elucidated as a member of metalloprotease in M35 family by proteomic approaches. The homology-modeling analysis revealed that versiase shares significant structural homology wuth the zinc metalloendopeptidase. The enzyme displayed maximum activity at 40 °C and pH 5.0. The activity of versiase was strongly inhibited by the metalloprotease inhibitors EDTA and BGTA. Furthermore, versiase hydrolyzed fibrin directly and indirectly via the activation of plasminogen, and it was able to hydrolyze the three chains (α, β, γ) of fibrin(ogen). Additionally, versiase demonstrated promising thrombolytic and anticoagulant activities, without many side-effects noticed. In conclusion, versiase appears to be a potent fibrinolytic enzyme deserving further investigation.

Thrombolytic and anticoagulant effects of a recombinant staphylokinase-hirudin fusion protein

A pure recombinant staphylokinase-hirudin fusion protein (SFH) was obtained by recombinant genetic engineering and purification techniques. The thrombolytic and anticoagulant activities of SFH were investigated using in vitro coagulation models and chromogenic assays. The results showed that intact SFH had targeted thrombolytic activity, and gained anticoagulant activity when cleaved by FXa. In addition, we investigated the pharmacodynamics of SFH in vivo using a variety of animal models, including a rat inferior vena cava thrombosis model, a rat coronary thrombosis model, a rabbit carotid artery thrombosis model and a canine coronary thrombosis model. We found that SFH had an obvious thrombolytic effect and could prevent and reduce re-embolization after thrombolysis and reduce the serious bleeding side effects caused by the combination of thrombolytic and anticoagulant drugs. The results suggest that SFH can be used for thrombolytic therapy in thromboembolic diseases.

Impact of intracoronary contrast injection pressure on reperfusion during primary percutaneous coronary intervention in acute ST-segment elevation myocardial infarction: A prospective randomized pilot study

Background

Distal embolization of plaque and thrombotic debris in the infarct-related artery (IRA) may lead to microvascular obstruction resulting in impaired myocardial reperfusion.

The aim of the study was to assess the impact of contrast injection pressure in IRA, during primary percutaneous coronary intervention (PCI), on myocardial reperfusion in patients with acute ST-segment elevation myocardial infarction (STEMI).

Methods

This prospective, randomized, open label, pilot trial evaluated acute STEMI patients who underwent primary PCI, with blinded evaluation of end points. Patients were assigned to higher injection pressure group A (550 pound/inch²) or lower injection pressure group B (200 pound/inch²). Primary endpoint was the postprocedural incidence of restored myocardial perfusion defined as myocardial blush grade (MBG) 3.

Results

Study included 100 consecutive acute STEMI patients, with median age of 63 (56–72) years (77% men) who were randomized to higher and lower injection pressure group. Baseline demographic, clinical and angiographic characteristics did not differ significantly between the groups. There were no significant differences between the study groups regarding difference in achieved MBG 3 (33 vs 36 patients, p = 0.247) nor regarding the ST-segment deviation score neither immediately after (3 vs 4 mm, p > 0.3) nor 24 h after primary PCI (2 vs 3 mm, p > 0.3).

Conclusion

There was no impact of lower intracoronary contrast injection pressure in comparison to higher injection pressure, during primary PCI in patients with acute STEMI, on myocardial reperfusion as assessed by MBG or ST segment changes in the ECG.

The study was registered at registry ClinicalTrials.gov with the registration number: NCT03445364, on February 26th 2018.

Intracoronary arterial retrograde thrombolysis with percutaneous coronary intervention: a novel use of thrombolytic to treat acute ST-segment elevation myocardial infarction

Background

Clearance of coronary arterial thrombosis is necessary in patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing urgent percutaneous coronary intervention (PCI). There is currently no highly-recommended method of thrombus removal during interventional procedures. We describe a new method for opening culprit vessels to treat STEMI: intracoronary arterial retrograde thrombolysis (ICART) with PCI.

Methods & Results

Eight patients underwent ICART. The guidewire was advanced to the distal coronary artery through the occlusion lesion. Then, we inserted a microcatheter into the distal end of the occluded coronary artery over the guidewire. Urokinase (5-10 wu) mixed with contrast agents was slowly injected into the occluded section of the coronary artery through the microcatheter. The intracoronary thrombus gradually dissolved in 3-17 min, and the effect of thrombolysis was visible in real time. Stents were then implanted according to the characteristics of the recanalized culprit lesion to achieve full revascularization. One patient experienced premature ventricular contraction during vascular revascularization, and no malignant arrhythmias were seen in any patient. No reflow or slow flow was not observed post PCI. Thrombolysis in myocardial infarction flow grade and myocardial blush grade post-primary PCI was 3 in all eight patients. No patients experienced bleeding or stroke.

Conclusions

ICART was accurate and effective for treating intracoronary thrombi in patients with STEMI in this preliminary study. ICART was an effective, feasible, and simple approach to the management of STEMI, and no intraprocedural complications occurred in any of the patients. ICART may be a breakthrough in the treatment of acute STEMI.

Pre-revascularization coronary wedge pressure as marker of adverse long-term left ventricular remodelling in patients with acute ST-segment elevation myocardial infarction

The aim of this study was to investigate the relationship between coronary wedge pressure (CWP), measured as a marker of pre-procedural microvascular obstruction, and left ventricular remodelling in high-risk ST-segment elevation myocardial infarction (STEMI) patients. Pre-revascularization CWP was measured in 25 patients with high-risk anterior STEMI. Left ventricular volumes and ejection fraction were echocardiographically measured at discharge and at follow-up. A 20% increase in left ventricular volumes was used to define remodelling. Patients with CWP ≤ 38 mmHg were characterized by late ventricular remodelling. Patients with CWP > 38 mmHg developed a progressive remodelling process which was associated with a significant 60 months increase in left ventricular volumes (P = 0.01 for end-systolic volume and 0.03 for end-diastolic volume) and a significant decrease in left ventricular ejection fraction (P = 0.05). A significant increase in both left ventricular end-systolic (P = 0.009) and end-diastolic volume (P = 0.02) from baseline to 60 months follow-up was recorded in patients with extracted thrombus length ≥2 mm. Pre-revascularization elevated CWP was associated with increased left ventricular volumes and decreased ejection fraction at long-term follow-up. CWP was a predictor of severe left ventricular enlargement, besides extracted thrombus quantity.

Value of global longitudinal strain by two dimensional speckle tracking echocardiography in predicting coronary artery disease severity

Background

Significant coronary artery stenosis might cause persistently impaired longitudinal left ventricle (LV) function at rest. LV global longitudinal strain (LVGLS) can be accurately assessed by 2D speckle-tracking strain echocardiography(2D-STE).

Objective

We aimed to evaluate the diagnostic accuracy of LV global longitudinal strain obtained by 2D-STE in prediction of severity of CAD.

Methods

Eighty patients with suspected stable angina pectoris were included. They underwent transthoracic echocardiography (TTE) to measure LV ejection fraction, 2-D-STE to measure GLS and coronary angiography (CA). The patients were divided into two groups: group 1 (58 patients) with significant (>70%) CAD, and group 2 (22 patients) with non-significant (<70%) CAD. Images were obtained in the apical long-axis, four-chamber, and two chamber views. Regional longitudinal systolic strain was measured in 17 myocardial segments and averaged to provide global longitudinal strain (LVGLS).

Results

There was significant decrease in GLS in group 1 compared to group 2 (−11.86 ± 2.89% versus −18.65 ± 0.79%, P < 0.000). The optimal cutoff value of GLS for prediction of significant CAD was −15.6% [AUC 0.88, 95% CI 0.78–0.96 p < 0.000]. The sensitivity, specificity and accuracy of GLS for detecting significant CAD were 93.1%, 81.8%,and 90% respectively.There was a significant positive correlation between GLS and EF (r = 0.33; p = 0.036).There was incremental significant decrease in GLS with increasing number of coronary vessels involved.

Conclusion

Measurement of global longitudinal strain using 2D speckle tracking echocardiography is sensitive and accurate tool in the prediction of severe CAD.

Calycosin‑7‑O‑β‑D‑glucoside attenuates ischemia‑reperfusion injury in vivo via activation of the PI3K/Akt pathway

The aim of the present study was to investigate the effects and mechanisms of calycosin‑7‑O‑β‑D‑glucoside (CG) on ischemia‑reperfusion (I/R) injury in vivo. Hemodynamic parameters, including ejection fraction (EF), fractional shortening (FS), left ventricular end‑systolic pressure (LVESP) and left ventricular end‑diastolic pressure (LVEDP) were monitored using an ultrasound system, and infarct size was measured using Evans blue/tetrazolium chloride double staining. The activities of serum creatine kinase (CK), lactate dehydrogenase (LDH) and superoxide dismutase (SOD), and the levels of malondialdehyde (MDA) were determined to assess the degree of myocardial injury and oxidative stress‑induced damage. The protein expression levels of cleaved‑caspase‑3, cleaved‑caspase‑9, phosphorylated (p)‑phosphatidylinositol 3‑kinase (PI3K) p85, PI3K p85, p‑Akt and Akt were determined using western blotting. The results demonstrated that pretreatment with high dose (H)‑CG markedly improved cardiac function, as evidenced by upregulated EF, FS and LVESP, and downregulated LVEDP. In addition, administration of CG resulted in significant decreases in infarct size in the I/R+low dose‑CG and I/R+H‑CG groups, compared with the I/R group. The activities of CK and LDH, and the levels of MDA in the I/R+H‑CG group were reduced, compared with those in the I/R group, whereas SOD activity was elevated. Treatment with CG inhibited the cleavage and activity of caspase‑3 and caspase‑9, and enhanced the phosphorylation of PI3K p85 and Akt. Notably, administration of the PI3K inhibitor, LY294002, markedly lowered the levels of p‑PI3K p85/p‑Akt, and eradicated the inhibitory effects of H‑CG on infarct size, myocardial injury and oxidative stress‑induced damage. Taken together, the results suggested that CG may alleviate I/R injury by activating the PI3K/Akt signaling pathway.

Discovery of small molecules with vasodilating characteristics and adjustable hydrolytic behavior

In this contribution the development of a new class of vasodilating compounds obtained by lead structure optimization is described. Three groups of compounds were synthesized and tested for their activity on various smooth muscle preparations of the guinea pig. Beside the lead compound 3a, the most interesting derivative was 1H-imidazole-1-carbothioic acid O-cyclohexyl ester hydrochloride (5b) with a good selective vasodilating potential on aorta and pulmonary artery rings (EC50 14 μM and 24 μM, respectively). Due to the properties of small molecules the hydrolysis behavior of the compounds can be easily adapted hence opening a new route in terms of duration of the agent's effect. With the aid of structure-activity relationship studies, structural motifs influencing the biological activity on isolated smooth muscle cell preparations of the synthesized compounds were proposed. The presented compounds offer good tools in identifying promising molecules as emergency therapy in myocardial infarction.

Effects of Pogostemon cablin Blanco extract on hypoxia induced rabbit cardiomyocyte injury

Background:

Pogostemonis Herba, the dried aerial part of Pogostemon cablin Blanco, is a well-known materia medica in Asia that is widely used for syndrome of gastrointestinal dysfunctions.

Objective:

This study was undertaken to examine whether Pogostemon cablin extract (PCe) might have any beneficial effect on hypoxia induced rabbit cardiomyocyte injury.

Materials and Methods:

Isolated cardiomyocytes were divided into three groups and the changes of cell viability in cardiomyocytes of hypoxic and hypoxia/reoxygenation group were determined. The effect of PCe on reactive oxygen species (ROS) generation, intracellular formation of ROS was also measured by monitoring the 2’,7’-dichlorofluorescein fluorescence.

Results:

PCe effectively protected the cells against both the hypoxia and reoxygenation induced injury, and the protective effect of PCe is not mediated by interaction with adenosine triphosphate-sensitive K⁺ channels. In the presence of PCe, production of ROS under chemical hypoxia was remarkably reduced which suggests that PCe might exert its effect as a ROS scavenger.

Conclusion:

The present study provides clear evidence for the beneficial effect of PCe on cardiomyocyte injury during hypoxia or reoxygenation following prolonged hypoxia.

Treatment of microvascular micro-embolization using microbubbles and long-tone-burst ultrasound: an in vivo study

Despite epicardial coronary artery reperfusion by percutaneous coronary intervention, distal micro-embolization into the coronary microcirculation limits myocardial salvage during acute myocardial infarction. Thrombolysis using ultrasound and microbubbles (sonothrombolysis) is an approach that induces microbubble oscillations to cause clot disruption and restore perfusion. We sought to determine whether this technique could restore impaired tissue perfusion caused by thrombotic microvascular obstruction. In 16 rats, an imaging transducer was placed on the biceps femoris muscle, perpendicular to a single-element 1-MHz treatment transducer. Ultrasound contrast perfusion imaging was performed at baseline and after micro-embolization. Therapeutic ultrasound (5000 cycles, pulse repetition frequency = 0.33 Hz, 1.5 MPa) was delivered to nine rats for two 10-min sessions during intra-arterial infusion of lipid-encapsulated microbubbles; seven control rats received no ultrasound-microbubble therapy. Ultrasound contrast perfusion imaging was repeated after each treatment or control period, and microvascular volume was measured as peak video intensity. There was a 90% decrease in video intensity after micro-embolization (from 8.6 ± 4.8 to 0.7 ± 0.8 dB, p < 0.01). The first and second ultrasound-microbubble sessions were respectively followed by video intensity increases of 5.8 ± 5.1 and 8.7 ± 5.7 dB (p < 0.01, compared with micro-embolization). The first and second control sessions, respectively, resulted in no significant increase in video intensity (2.4 ± 2.3 and 3.6 ± 4.9) compared with micro-embolization (0.6 ± 0.7 dB). We have developed an in vivo model that simulates the distal thrombotic microvascular obstruction that occurs after primary percutaneous coronary intervention. Long-pulse-length ultrasound with microbubbles has a therapeutic effect on microvascular perfusion and may be a valuable adjunct to reperfusion therapy for acute myocardial infarction.

Implications of ventricular arrhythmia “bursts” with normal epicardial flow, myocardial blush, and ST-segment recovery in anterior ST-elevation myocardial infarction reperfusion: A biosignature of direct myocellular injury “downstream of downstream”

Aims:

Establishing epicardial flow with percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) is necessary but not sufficient to ensure nutritive myocardial reperfusion. We evaluated whether adding myocardial blush grade (MBG) and quantitative reperfusion ventricular arrhythmia “bursts” (VABs) surrogates provide a more informative biosignature of optimal reperfusion in patients with Thrombolysis in Myocardial Infarction (TIMI) 3 flow and ST-segment recovery (STR).

Methods and results:

Anterior STEMI patients with final TIMI 3 flow had protocol-blinded analyses of simultaneous MBG, continuous 12-lead electrocardiogram (ECG) STR, Holter VABs, and day 5–14 SPECT imaging infarct size (IS) assessments. Over 20 million cardiac cycles from >4500 h of continuous ECG monitoring in subjects with STR were obtained. IS and clinical outcomes were examined in patients stratified by MBG and VABs. VABs occurred in 51% (79/154) of subjects. Microcirculation (MBG 2/3) was restored in 75% (115/154) of subjects, of whom 53% (61/115) had VABs. No VABs were observed in subjects without microvascular flow (MBG of 0). Of 115 patients with TIMI 3 flow, STR, and MBG 2/3, those with VABs had significantly larger IS (median: 23.0% vs 6.0%, p=0.001). Multivariable analysis identified reperfusion VABs as a factor significantly associated with larger IS ( p=0.015).

Conclusions:

Despite restoration of normal epicardial flow, open microcirculation, and STR, concomitant VABs are associated with larger myocardial IS, possibly reflecting myocellular injury in reperfusion settings. Combining angiographic and ECG parameters of epicardial, microvascular, and cellular response to STEMI intervention provides a more predictive “biosignature” of optimal reperfusion than do single surrogate markers.

Acute coronary syndrome in two patients with mechanical valve prostheses

We report 2 similar cases of embolic myocardial infarction due to thrombus on a mechanical prosthesis despite anticoagulation therapy. In our first case, aspiration of the thrombus was performed successfully. Our second patient was given medical treatment with target international normalized ratio values between 3.5 and 4.0.

Coronary microvascular dysfunction: an update

Many patients undergoing coronary angiography because of chest pain syndromes, believed to be indicative of obstructive atherosclerosis of the epicardial coronary arteries, are found to have normal angiograms. In the past two decades, a number of studies have reported that abnormalities in the function and structure of the coronary microcirculation may occur in patients without obstructive atherosclerosis, but with risk factors or with myocardial diseases as well as in patients with obstructive atherosclerosis; furthermore, coronary microvascular dysfunction (CMD) can be iatrogenic. In some instances, CMD represents an epiphenomenon, whereas in others it is an important marker of risk or may even contribute to the pathogenesis of cardiovascular and myocardial diseases, thus becoming a therapeutic target. This review article provides an update on the clinical relevance of CMD in different clinical settings and also the implications for therapy.

Low frequency mechanical actuation accelerates reperfusion in-vitro

BACKGROUND

Rapid restoration of vessel patency after acute myocardial infarction is key to reducing myocardial muscle death and increases survival rates. Standard therapies include thrombolysis and direct PTCA. Alternative or adjunctive emergency therapies that could be initiated by minimally trained personnel in the field are of potential clinical benefit. This paper evaluates a method of accelerating reperfusion through application of low frequency mechanical stimulus to the blood carrying vessels.

MATERIALS AND METHOD

We consider a stenosed, heparinized flow system with aortic-like pressure variations subject to direct vessel vibration at the occlusion site or vessel deformation proximal and distal to the occlusion site, versus a reference system lacking any form of mechanical stimulus on the vessels.

RESULTS

The experimental results show limited effectiveness of the direct mechanical vibration method and a drastic increase in the patency rate when vessel deformation is induced. For vessel deformation at occlusion site 95% of clots perfused within 11 minutes of application of mechanical stimulus, for vessel deformation 60 centimeters from the occlusion site 95% percent of clots perfused within 16 minutes of stimulus application, while only 2.3% of clots perfused within 20 minutes in the reference system.

CONCLUSION

The presented in-vitro results suggest that low frequency mechanical actuation applied during the pre-hospitalization phase in patients with acute myocardial infarction have potential of being a simple and efficient adjunct therapy.

One-year clinical outcome of patients treated with or without abciximab in rescue coronary angioplasty

BACKGROUND

The clinical results of abciximab administration during rescue angioplasty (PCI) are poorly investigated.

METHODS

We evaluated the outcome of 406 consecutive patients undergoing rescue PCI treated with (n=218) or without (n=188) abciximab and a clopidogrel loading dose of 300 mg. The end point was the incidence of major cardiac adverse events (MACE) defined as death, recurrent acute myocardial infarction (AMI) and target vessel revascularization at 30 days and 1 year. The predictors of MACE were also investigated.

RESULTS

No differences were found in MACE between the groups treated with or without abciximab at 30 days (15 and 20, p=0.67) and 1 year (23 and 29, p=0.85). Stepwise logistic regression analysis identified: cardiogenic shock (Odds Ratio [OR]=17.8, 95% confidence interval [CI] 5-99, p=0.0001), age (OR=1.099, 95% CI 1.04-1.15, p=0.0001), TIMI flow 0-1 after procedure (OR=5.51, 95% CI 1.72-17.6, p=0.004) as independent predictors of MACE at 30 days. Cox proportional hazards model identified: cardiogenic shock (adjusted hazard ratio [HR]=3.83, 95% confidence interval [CI] 1.76-8.35, p=0.01), age (HR=3.7, 95% CI 1.75-8.3, p=0.01), TIMI flow 0-1 after procedure (HR=1.04, 95% CI 1.01-1.07, p=0.001 as predictors of MACE at 1 year). After propensity score adjustments the predictors of MACE did not change.

CONCLUSION

There were no differences in MACE at 30 days and 1 year in patients treated with or without abciximab during rescue PCI after a clopidogrel loading dose of 300 mg. Cardiogenic shock, age and TIMI flow 0 and 1 after PCI were predictors of MACE.

Successful medical management of a left ventricular thrombus and aneurysm following failed thrombolysis in myocardial infarction

We report the case of a patient with an extensive anterior myocardial infarction complicated by left ventricular systolic dysfunction, left ventricular apical thrombus and an apical left ventricular aneurysm following failed thrombolysis. We obtained serial two-dimensional echocardiograms at short intervals in the acute phase and also during the months of recovery and follow up. The patient was successfully and exclusively medically managed.

Association of fragmented QRS complex with myocardial reperfusion in acute ST-elevated myocardial infarction

In this study, we aimed to evaluate the relationship between TIMI myocardial perfusion (TMP) grade, as an indicator of myocardial reperfusion, and fragmented QRS (fQRS) in standard 12-lead electrocardiogram. Also, we evaluate fQRS is an additional indicator of myocardial reperfusion. One hundred patients admitted with first STEMI to Coronary Intensive Care Unit and who were used thrombolytic therapy was included in this retrospective study. Standard 12-lead electrocardiogram records of patients simultaneous with coronary angiography (second day) were assessed and analysed for the presence of fQRS. Also, coronary angiography images were analyzed to identify the infarct related artery, TIMI grade of infarct related artery and TMP grade of infarct related artery. The patients with fQRS demonstrated a significantly lower TMP grade, TIMI grade and ejection fraction compared with the non-fQRS patients (P = 0.004, P = 0.003, P = 0.02 respectively). The patients with inadequate myocardial reperfusion demonstrated a significantly higher fQRS compared with the adequate myocardial reperfusion patients. (56.9% versus 23.5%, P = 0.002 respectively). On correlation analysis, there was a significant negative correlation between fQRS and left ventricular ejection fraction (r = -232, P = 0.02) TMP grade and adequate myocardial reperfusion (TMP 3) showed significant negative correlation with fQRS (r = -0.370, P = 0.000; r = -0.318, P = 0.001 respectively). Presence of fragmented QRS in STEMI patients was associated with inadequate myocardial reperfusion and it can be used as a simple, noninvasive parameter to evaluate myocardial reperfusion.

A new drug delivery system for intravenous coronary thrombolysis with thrombus targeting and stealth activity recoverable by ultrasound

OBJECTIVES

The purpose of this study was to develop a new intelligent drug delivery system for intracoronary thrombolysis with a strong thrombolytic effect without increasing bleeding risk.

BACKGROUND

Rapid recanalization of an occluded coronary artery is essential for better outcomes in acute myocardial infarction. Catheter-based recanalization is widely accepted, but it takes time to transport patients. Although the current fibrinolytic therapy can be started quickly, it cannot achieve a high reperfusion rate. Recently, we generated nanoparticles comprising tissue-type plasminogen activator (tPA), basic gelatin, and zinc ions, which suppress tPA activity by 50% with 100% recovery by ultrasound (US) in vitro.

METHODS

The thrombus-targeting property of nanoparticles was examined by an in vitro binding assay with von Wilbrand factor and with a mouse arterial thrombosis model in vivo. The thrombolytic efficacy of nanoparticles was evaluated with a swine acute myocardial infarction model.

RESULTS

Nanoparticles bound to von Wilbrand factor in vitro and preferentially accumulated at the site of thrombus in a mouse model. In a swine acute myocardial infarction model, plasma tPA activity after intravenous injection of nanoparticles was approximately 25% of tPA alone and was recovered completely by transthoracic US (1.0 MHz, 1.0 W/cm(2)). During US application, plasma tPA activity near the affected coronary artery was recovered and was higher than that near the femoral artery. Although treatment with tPA alone (55,000 IU/kg) recanalized the occluded coronary artery in only 1 of 10 swine, nanoparticles containing the same dose of tPA with US achieved recanalization in 9 of 10 swine within 30 min.

CONCLUSIONS

We developed an intelligent drug delivery system with promising potential for better intravenous coronary thrombolysis.

Diastolic timed Vibro-Percussion at 50 Hz delivered across a chest wall sized meat barrier enhances clot dissolution and remotely administered Streptokinase effectiveness in an in-vitro model of acute coronary thrombosis

Background

Low Frequency Vibro-Percussion (LFVP) assists clearance of thrombi in catheter systems and when applied to the heart and timed to diastole is known to enhance coronary flow. However LFVP on a clotted coronary like vessel given engagement over a chest wall sized barrier (to resemble non-invasive heart attack therapy) requires study.

Methods

One hour old clots (n=16) were dispensed within a flexible segment of Soft-Flo catheter (4 mm lumen), weighted, interfaced with Heparinized Saline (HS), secured atop a curved dampening base, and photographed. A ~4 cm meat slab was placed over the segment and randomized to receive intermittent LFVP (engaged, - disengaged at 1 second intervals), or no LFVP for 20 minutes. HS was pulsed (~120/80 mmHg), with the diastolic phase coordinated to match LFVP delivery. The segment was then re-photographed and aspirated of fluid to determine post clot weight. The trial was then repeated with 0.5 mls of Streptokinase (15,000 IU/100 microlitre) delivered ~ 2 cm upstream from the clot.

Results

LFVP - HS only samples (vs. controls) showed; a) development of clot length fluid channels absent in the control group (p < 0.0002); b) enhanced dissolved clot mixing scores ( 5.0 vs. 0.8, p < 2.8 E – 6); and c) increased percent clot dissolution (23.0% vs. 1.8% respectively, p < 8.5 E-6). LFVP - SK samples had a similar comparative clot disruptive profile, however fluid channels developed faster and percent clot dissolution more than doubled (51.0% vs. 3.0%, p< 9.8 E- 6).

Conclusion

Diastolic timed LFVP (50 Hz) engaged across a chest wall sized barrier enhances clot disruptive effects to an underlying coronary like system.

Endo-epicardial homogenization of the scar versus limited substrate ablation for the treatment of electrical storms in patients with ischemic cardiomyopathy

OBJECTIVES

This study investigated the impact on recurrences of 2 different substrate approaches for the treatment of these arrhythmias.

BACKGROUND

Catheter ablation of electrical storms (ES) for ventricular arrhythmias (VAs) has shown moderate long-term efficacy in patients with ischemic cardiomyopathy.

METHODS

Ninety-two consecutive patients (81% male, age 62 ± 13 years) with ischemic cardiomyopathy and ES underwent catheter ablation. Patients were treated either by confining the radiofrequency lesions to the endocardial surface with limited substrate ablation (Group 1, n = 49) or underwent endocardial and epicardial ablation of abnormal potentials within the scar (homogenization of the scar, Group 2, n = 43). Epicardial access was obtained in all Group 2 patients, whereas epicardial ablation was performed in 33% (14) of these patients.

RESULTS

Mean ejection fraction was 27 ± 5. During a mean follow-up of 25 ± 10 months, the VAs recurrence rate of any ventricular tachycardia (VTs) was 47% (23 of 49 patients) in Group 1 and 19% (8 of 43 patients) in Group 2 (log-rank p = 0.006). One patient in Group 1 and 1 patient in Group 2 died at follow-up for noncardiac reasons.

CONCLUSIONS

Our study demonstrates that ablation using endo-epicardial homogenization of the scar significantly increases freedom from VAs in ischemic cardiomyopathy patients.

Effect of acoustic conditions on microbubble-mediated microvascular sonothrombolysis

Ultrasound (US) mediated microbubble (MB) destruction facilitates thrombolysis of the epicardial coronary artery in acute myocardial infarction (AMI) but its effect on microvascular thromboemboli remains largely unexplored. We sought to define the acoustic requirements for effective microvascular sonothrombolysis. To model microembolization, microthrombi were injected and entrapped in a 40 μm pore mesh, increasing upstream pressure, which was measured as an index of thrombus burden. MBs (2.0 × 10(6) MBs/mL) were then infused while pulsed US (1 MHz) was delivered to induce MB destruction immediately adjacent to the thrombus. Upstream pressure decreased progressively during US delivery, indicating a reduction in thrombus burden. More rapid and complete lysis occurred with increasing peak negative acoustic pressure (1.5 MPa > 0.6 MPa) and increasing pulse length (5000 cycles > 100 cycles). Additionally, similar lytic efficacy was achieved at 1.5 MPa without tPA as was at 1.0 MPa with tPA. This model uniquely provides a means to systematically evaluate multiple acoustic and microbubble parameters for the optimization of microvascular sonothrombolysis. This treatment approach for thrombotic microvascular obstruction may obviate the need for adjunctive rt-PA and could have important clinical cost and safety benefits.

A study of clinical presentation and delays in management of acute myocardial infarction in community

To assess the medico social demographics of acute myocardial infarction (AMI) in our community we studied 609 patients presenting between January 2008 to December 2008 with a detailed questionnaire in four centres of UP. Medical attention was sought late (> 6 hours) in 316 (51.6%), thrombolysis was obtained in 45.2% (275) and presentation was atypical in 16.3% (99). 36.2% (221) had pre-monitory symptoms of which 68% (150) ignored the same while of 32% (71) who did seek medical attention 47.9% (37) were brushed away as non-cardiac in origin. 20.3% (46/226) of hypertension, 23.2% (43/185) of diabetes and 83.4% (91/109) of hyperlipidaemia was diagnosed post event. We conclude that at least half of patients with AMI do not get definitive therapy, at least one in 10 patients do not have the classical symptoms, reasonable proportion are unaware of their risk factors, and a good majority have pre-monitory symptoms which get overlooked.

Reperfusion Strategies for Acute Ischemic Stroke

Stroke remains a major cause of morbidity and mortality worldwide. Despite preventive measures, effective management strategies are needed to reduce the morbidity and mortality associated with this devastating condition. While the management of hemorrhagic stroke is mostly limited to supportive care, reperfusion strategies in ischemic stroke have been developed and continue to evolve. Conceptually, the pathophysiology of ischemic stroke is similar to that of acute myocardial infarction and the objective of management is similar (ie, to rapidly restore normal flow to reduce permanent damage). It is, therefore, not surprising that the management of acute ischemic stroke includes intravenous (IV) thrombolysis, the only Food and Drug Administration (FDA)-approved strategy at this point. In addition, there are a myriad of emerging endovascular interventional techniques. We review the current literature and discuss some of the technical aspects of endovascular therapy in the setting of acute ischemic stroke.

A study to determine chest wall vibratory attachment interface locations for a low frequency sonic vibrator in treatment of acute coronary thrombosis

Our institution is developing a non-invasive Diastolic Timed Vibrator (DTV) to enhance emergency clearance of acute coronary thrombosis. Sonic frequency diastolic vibro-percussion (i.e. 50 Hz, 2 mm amplitude) applied upon the rib-spaces of the left sternal border has shown to improve left ventricular performance and coronary flow in human volunteers. However, therapeutic acoustic penetrability cannot be assumed depending on varying chest size and lung position which attenuates acoustic transmissions. Furthermore, chest locations enabling a direct lung free pathway overlying the base of the heart (wherein the coronaries arise) should be promoted, while locations overlying the left ventricular apex (site of potential thrombus formation) should be avoided. We therefore set out to determine preferred chest wall placement positions for a vibratory interface suitable for treatment of ST Elevation Myocardial Infarction (STEMI). Inter-Costal Space (ICS) positions to the left or right of the sternum were interrogated in 90 adults following routine Echocardiography to ascertain whether the base of the heart could be imaged (hence inferring acoustic transmissibility), and to determine over what part of the heart each transducer position was overlying. The third and fourth ICS proximate the left sternal border provided acoustic transmissibility in 96 and 100% of cases respectively, with only one unwanted occurrence from the fourth ICS where the transducer overlaid the apical third of the left ventricle. Acoustic transmissibility from third and fourth ICS right sternal border was documented in 53 and 85% of cases respectively. A vibration interface in STEMI treatment should allow for contact overlying the left and right third and fourth ICS generally proximate the sternal borders. As vibration transmission to the cardiac apex and/or left atrium cannot be completely avoided, vibration therapy should be contra-indicated in late presenters for antero-septal apical STEMI, and in cases of new onset atrial fibrillation persisting greater than 48 h which have not been adequately anti-coagulated.

The effectiveness of the practice of correction and republication in the biomedical literature

OBJECTIVE

This research measures the effectiveness of the practice of correction and republication of invalidated articles in the biomedical literature by analyzing the rate of citation of the flawed and corrected versions of scholarly articles over time. If the practice of correction and republication is effective, then the incidence of citation of flawed versions should diminish over time and increased incidence of citation of the republication should be observed.

METHODS

This is a bibliometric study using citation analysis and statistical analysis of pairs of flawed and corrected articles in MEDLINE and Web of Science.

RESULTS

The difference between citation levels of flawed originals and corrected republications does not approach statistical significance until eight to twelve years post-republication. Results showed substantial variability among bibliographic sources in their provision of authoritative bibliographic information.

CONCLUSIONS

Correction and republication is a marginally effective biblioremediative practice. The data suggest that inappropriate citation behavior may be partly attributable to author ignorance.

Myocardial no-reflow in humans

In a variable proportion of patients presenting with ST-segment elevation myocardial infarction, ranging from 5% to 50%, primary percutaneous coronary intervention achieves epicardial coronary artery reperfusion but not myocardial reperfusion, a condition known as no-reflow. Of note, no-reflow is associated with a worse prognosis at follow-up. The phenomenon has a multifactorial pathogenesis including: distal embolization, ischemia-reperfusion injury, and individual predisposition of coronary microcirculation to injury. Moreover, it is spontaneously reversible in some patients, thus suggesting that it might be amenable to treatment also when we fail to prevent it. Several recent studies have shown that biomarkers and other easily available clinical parameters can predict the risk of no-reflow and can help in the assessment of the multiple mechanisms of the phenomenon. Several therapeutic strategies have been tested for the prevention and treatment of no-reflow. In particular, thrombus aspiration before stent implantation prevents distal embolization and has been recently shown to improve myocardial perfusion and clinical outcome as compared with the standard procedure. However, it is conceivable that the relevance of each pathogenetic component of no-reflow is different in different patients, thus explaining the occurrence of no-reflow despite the use of mechanical thrombus aspiration. Thus, in this review article, for the first time, we propose a personalized management of no-reflow on the basis of the assessment of the prevailing mechanisms of no-reflow operating in each patient.

Systematic review of fibrinolytic-facilitated percutaneous coronary intervention: potential benefits and future challenges

BACKGROUND

Facilitated percutaneous coronary intervention (PCI) is defined as the administration of fibrinolytic therapy and/or glycoprotein (GP) IIb/IIIa inhibitors to minimize myocardial ischemia time while waiting for PCI. A pooled meta-analysis suggested that facilitated PCI was associated with higher rates of mortality and morbidity compared with nonfacilitated PCI.

OBJECTIVE

The heterogeneous and complex trials of facilitated PCI were systematically reviewed to identify where this strategy may be beneficial and deserving of further research.

METHODS

MEDLINE, EMBASE, the Cochrane database, the Internet and conference proceedings were searched to obtain relevant trials. Human studies that randomly assigned patients to fibrinolytic-facilitated PCI (administration of fibrinolytic therapy alone or in combination with GP IIb/IIIa inhibitors before angiography) versus nonfacilitated PCI were included.

RESULTS

Nine trials encompassing 3836 patients were reviewed. The facilitated PCI strategy was fibrinolytic therapy alone in seven trials and half-dose fibrinolytic therapy plus GP IIb/IIIa inhibitors in two trials. In patients who had fibrinolysis less than 2 h after symptom onset (mainly in the prehospital setting) and/or slightly delayed PCI 3 h to 24 h after fibrinolysis, facilitated PCI was associated with the greatest Thrombolysis In Myocardial Infarction (TIMI) grade 3 flow and a trend toward reduced mortality. Overall, facilitated PCI was associated with increased intracranial hemorrhage and reinfarction. Combining half-dose fibrinolytic therapy and GP IIb/IIIa inhibitors reduced reinfarction but increased major bleeding.

CONCLUSIONS

Facilitated PCI cannot be recommended outside of experimental protocols at this time. Further research should focus on selecting patients with higher benefit-to-risk ratios and performing prehospital fibrinolysis with optimal antiplatelet or antithrombin therapy, as well as slightly delayed PCI in patients who are stable or geographically removed from PCI facilities.

Early predictors of late dilation and remodeling after thrombolized anterior transmural myocardial infarction

BACKGROUND AND HYPOTHESIS

Dilation of the left ventricle after myocardial infarction is associated with an adverse prognosis. There are no clinical studies on the role viable myocardium in the infarcted area assumes in relation to the development of late ventricular remodeling. The hypothesis of this study was to define the relation between remodeling and the presence of viable but akinetic myocardium in the infarct area and to identify early predictors of left ventricular (LV) dilation at 1 year.

METHODS

In all, 92 consecutive patients with myocardial infarction were divided into two groups according to their ventricular volumes. Group I included 57 patients with normal volumes at discharge (9 +/- 3 days after acute infarction) and after 12 months or with LV dilation at discharge who had a normalization of their volumes over a 12-month period. Group II included 35 patients who, independent of their initial volumes, developed LV dilation during follow-up. Low-dose dobutamine infusion was utilized at discharge for echocardiographic evaluation of contractile recovery of viable myocardial segments.

RESULTS

At the first control, patients in Group I presented an end-diastolic volume index (EDVI) of 100 +/- 7 ml/m2 which decreased to 68.8 +/- 6.5 ml/m2 12 months later (p < 0.0001), and an end-systolic volume index (ESVI) of 47.6 +/- 6.7 ml/m2 at the first control and 30.5 +/- 8.8 ml/m2 after 12 months (p < 0.001). Patients in Group II presented a mean EDVI of 116.2 +/- 8.1 ml/m2 at the first control and 138.8 +/- 8 ml/m2 12 months later (p < 0.001), and a mean ESVI of 68.8 +/- 6.5 ml/m2 at the first control and 79.5 +/- 5.4 after 12 months (p < 0.01). Ventricular mass index (VMI) in Group I increased from 106.4 +/- 11 to 122.3 +/- 15 g/m2 (p < 0.01), while in Group II it decreased from 101.1 +/- 10 to 98.7 +/- 8 g/m2 (p = NS). In Group I, mass-to-volume ratio was 1.15 +/- 0.1 g/ml at the first control and 1.67 +/- 0.1 g/ml 12 months later (p < 0.001), while in Group II it declined from 0.88 +/- 0.1 to 0.69 +/- 0.1 g/ml (p < 0.01). The multivariate analysis revealed that ejection fraction < or = 40%, restrictive filling pattern, wall motion score index > 2.5 in response to dobutamine infusion, and mass-to-volume ratio < or = 1 g/ml, all at discharge, as well as an occluded left anterior descending artery discriminate in favor of late LV dilation and remodeling.

CONCLUSIONS

Correct use of noninvasive strategies should result in early identification of postinfarct patients who are at risk of developing LV remodeling.

Reperfusion revisited: beyond TIMI 3 flow

Therapy for acute myocardial infarction has advanced dramatically since the early 1980s with the use of early intravenous fibrinolytic therapy. Combining low-dose fibrinolysis and platelet lysis appears to provide an additional increase in infarct-related artery (IRA) patency, but the large-scale mortality reduction trials evaluating this strategy are just getting under way. Recently, considerable attention has shifted away from the epicardial arteries to the microvasculature. Contemporary evidence suggests that epicardial patency does not necessarily translate to actual perfusion at the myocardial level. Techniques to evaluate beyond thrombolysis in myocardial infarction (TIMI) epicardial flow are now available and validated. In addition, there are promising treatments for the prevention or alleviation of certain forms of microvascular obstruction. This review attempts to clarify the confusion surrounding epicardial flow and "myocardial malperfusion" and to provide some insight into the next direction in acute myocardial infarction therapeutics.

Rescue use of abciximab improves regional left ventricular function after early incomplete reperfusion in acute myocardial infarction

BACKGROUND

Abciximab was shown to have important beneficial effects beyond the maintenance of epicardial coronary artery patency. However, it remains uncertain whether abciximab may lead to a better functional outcome in patients with acute myocardial infarction (AMI) and with incomplete reperfusion after primary angioplasty (PA).

HYPOTHESIS

The study aimed to evaluate whether rescue use of abciximab may lead to a better functional outcome in such patients.

METHODS

The study included 25 patients with first AMI who met the following criteria: (1) total occlusion of the infarct-related artery, (2) PA within 12 h of symptom onset, (3) postprocedural diameter stenosis < 30%, and final Thrombolysis in Myocardial Infarction (TIMI) flow grade 2. Echocardiographic examination was performed before and on Days 7 and 30 after PA. The study population was divided into two groups: Group 1 (usual care, n = 13) and Group 2 (rescue use of abciximab, n = 12). Baseline characteristics were similar between the two groups.

RESULTS

Peak level of creatine kinase was higher in Group 1 than in Group 2 (5,800+/-2,700 vs. 3,800+/-2,000 U/I, p < 0.05). At 1 month follow-up, infarct zone wall motion score index (2.71+/-0.26 vs. 2.05+/-0.63, p < 0.01) and left ventricular (LV) volume indices were smaller in Group 2 than in Group 1, whereas LV ejection fraction was higher in Group 2 than in Group 1 (52.1+/-7.8 vs. 42.1+/-6.4, p < 0.01). At 1-month, abciximab was the only independent predictor of wall motion recovery index by multiple regression analysis.

CONCLUSIONS

Rescue use of abciximab may reduce the infarct size in patients with AMI and TIMI grade 2 flow after PA, which may improve the recovery of regional LV function.

A risk-predictive score for cardiogenic shock after acute myocardial infarction in Chinese patients

BACKGROUND

Cardiogenic shock after acute myocardial infarction (AMI) remains a poor prognosis. Although numerous studies discussed the predictors of cardiogenic shock complicating AMI, the data in Chinese patients is still absent. The goal of this study is to develop a risk-predictive score for cardiogenic shock after AMI, among Chinese patients, so as to guide clinicians to prevent cardiogenic shock.

METHODS

Patients with ST-segment elevated AMI were provided by two Chinese hospitals from 1994 to 2004. Baseline characteristics of each case were documented. Multivariable logistic regression modeling techniques were used to develop a model to predict the occurrence of cardiogenic shock within 72 h after admission. On the basis of the coefficients in the model, a risk score was developed for the probability of cardiogenic shock. To test its viability, another population, which was consistent with the original population, confirmed the scoring.

RESULTS

Among 2,077 patients, 184 cases developed cardiogenic shock within 72 h. Age, gender, BMI, killip class, MI location, multivessel disease, previous MI, family history of CAD, and thrombolytic therapy were strong predictors for shock after AMI. A risk-predictive score for shock was developed. It predicted cardiogenic shock accurately in another Chinese population.

CONCLUSIONS

A predictive model is developed in Chinese patients with AMI for the first time. It is based on some simple parameters, which can be easily obtained by clinicians. The risk score derived from the model can predict cardiogenic shock accurately.

Non-invasive low frequency vibration as a potential emergency adjunctive treatment for heart attack and stroke. An in vitro flow model

BACKGROUND

Myocardial infarction and stroke (arterial thrombosis) comprise the leading killers and sources of disability in the developed world, and incomplete thrombolysis along with high bleeding rates (plus late presentations to cathlabs) have prompted an intensive search for alternative or adjunctive emergency therapies. Transcutaneous ultrasound has been studied in remediation of thrombosis, but has been problematic due to poor penetration, risk of arterial damage, plus the apparent need for a highly skilled approach. Surprisingly there has been no reported studies on the much simpler application of transcutaneous low frequency vibration (well known for its superior penetration and flow enhancing characteristics) to assist arterial thrombolysis. The aim of our experiment therefore was to test the hypothesis whether vibration (i.e. approximately 100 Hz, 0.5 mm), when applied across an attenuating barrier, would assist recanulization of a thrombosed flow system held at arterial like pressure.

METHODS

A teddy bear with a 2 cm slab of New York Steak placed upon its chest surface was used as a test subject with an in-dwelling catheter (approximately 4.0 mm lumen) cannulated through the bear's thorax. In a series of test runs (n=30), a 2 h old (or older) blood clot was injected into the catheter such as to occlude it at a stenosis site (approximately 90% luminal narrowing) created by a clamp placed along the catheter within the teddy's chest region. A pressurized heparinized IV system was in all cases connected to the catheter such as to yield an "arterial like" lumen pressure proximal the obstruction. For each test run, after a twenty minute observation period to confirm stability of the occlusion, test groups where randomized to receive vibration to the slab of steak upon the teddy's "chest wall" (generally overlying the site of the thrombotic obstruction), or no vibration for an evaluation period of up to 45 min.

RESULTS

Catheter reflow occurred rapidly (median reflow-time 90 s) in the vibration groups within the evaluation period (i.e. 15/17), while the system remained otherwise blocked in the control groups receiving no vibration (i.e. 0/13). The difference in flow system patency rate for the vibration groups vs. the control groups was statistically significant (P=0.0000009).

CONCLUSIONS

The frequent and generally rapid re-establishment of flow in vibration groups compared to the complete absence of reflow in control groups confirms the hypothesis that vibration applied across a physical barrier assists clearance of a blood clot in a stenosed flow system under systemic levels of pressure. We studied the incidence of clearance of a blood clot within a stenosed, heparanized catheter system held at arterial like pressure that was treated with externally delivered low frequency vibration (applied proximate the thrombotic occlusion across an attenuating medium--a 2 cm thick slab of New York Steak--at approximately 100 Hz, 0.5 mm), versus no vibration. Reflow in test runs incorporating vibration occurred faster, and resulted in significantly greater recanulization rates in the catheter system versus test runs without vibration (P=0.0000009). Non-invasive vibration holds potential as an adjunct to pharmacologic therapy in treatment of acute arterial thrombosis. Further study of this technique appears warranted in live animal models.

Ultrasound Accelerates Thrombolysis of Acutely Induced Platelet-Rich Thrombi Similar to Those in Acute Myocardial Infarction

BACKGROUND

Although sonothrombolysis has been studied for development of recanalization that is safer and more efficacious than the methods currently used, there have been no studies of the efficacy of sonothrombolysis for the platelet-rich thrombi that typically cause acute myocardial infarction (AMI). The effects of adding ultrasound (US) to pharmacological lysis of platelet-rich thrombi was examined in a rabbit model of femoral artery occlusion.

METHODS AND RESULTS

In 35 rabbits, the right femoral artery was balloon-injured repeatedly at 4-week intervals to induce platelet-rich thrombi. Two hours after the induction of occlusive thrombi, 27,500 IU/kg tissue plasminogen activator (tPA) were injected via an ear vein, with or without transcutaneous US (continuous wave, 1 MHz, 0.75 W/cm2), or 13,750 IU/kg tPA was administered with US (n=10). Significantly higher rates of successful thrombolysis (Thrombolysis In Myocardial Infarction grade 3) were observed with US (90.0%) than without it (10.0%), irrespective of the dose of tPA used (p<0.01). The peak flow velocity in affected femoral arteries was significantly higher with US (p<0.01), and histological examination confirmed complete dissolution of thrombi. However, the thrombi were not affected by US alone (n=5).

CONCLUSIONS

US facilitates thrombolysis of platelet-rich thrombi and could be a useful component of thrombolytic therapy following AMI.

Transfer for urgent percutaneous coronary intervention early after thrombolysis for ST-elevation myocardial infarction: the TRANSFER-AMI pilot feasibility study

BACKGROUND

Most hospitals in Canada do not have percutaneous coronary intervention (PCI) facilities and use thrombolysis as reperfusion therapy for ST-elevation myocardial infarction (STEMI). Urgent PCI after thrombolysis may optimize reperfusion and prevent reinfarction and recurrent ischemia.

OBJECTIVE

To determine the feasibility of transferring high-risk STEMI patients from community hospitals in Ontario to PCI centres for urgent PCI within 6 h of thrombolysis.

METHODS

Patients with anterior or high-risk inferior STEMI received tenecteplase and were urgently transferred to PCI centres. PCI was performed if at least 70% stenosis was present in the infarct-related artery, regardless of flow, using coronary stents. Transfer of stable patients back to community hospitals was encouraged 24 h to 48 h after PCI.

RESULTS

Eighteen patients were transferred and underwent PCI a median of 3.9 h (range 2.7 h to 6.4 h) after thrombolysis. No complications occurred during transfer. One death occurred that was related to failed reperfusion and cardiogenic shock. Minor access-site bleeding occurred in five patients. Fifteen patients were transferred back to their community hospitals within 24 h of PCI. There were no further deaths or reinfarctions at one-year follow-up.

CONCLUSIONS

Transfer of high-risk STEMI patients for urgent PCI within 6 h after thrombolysis appears feasible. The randomized trial phase of the Trial of Routine ANgioplasty and Stenting after Fibrinolysis to Enhance Reperfusion in Acute Myocardial Infarction (TRANSFER-AMI) will compare this strategy with standard treatment after thrombolysis.

ST variability during the first 4 hours of acute myocardial infarction predicts 1-year mortality

BACKGROUND

Early and complete myocardial reperfusion is the goal when treating a patient with acute myocardial infarction. To achieve this in each individual, an on-line, accurate, easily handled and preferably noninvasive technique to monitor flow alterations is needed. Recurrent ST-segment elevation has been shown to reflect cyclic disturbances in perfusion.

METHODS

We have retrospectively analyzed ST variability in 102 patients with acute myocardial infarction randomized to 100 mg of rt-Pa or placebo. Patients were monitored for 24 hours using vectorcardiography.

RESULTS

Patients alive at one year (86%) had significantly less ST variability during the first four hours: 4.3 versus 7.1 episodes, P = 0.007. Patients having six or more ST episodes showed a 31.3% one-year mortality as compared to no mortality in patients having no ST variability. Furthermore ST variability was reduced by fibrinolysis.

CONCLUSION

Early ST variability detectable in real time is associated with worse outcome.

Thrombus aspiration before primary angioplasty improves myocardial reperfusion in acute myocardial infarction: the DEAR-MI (Dethrombosis to Enhance Acute Reperfusion in Myocardial Infarction) study

OBJECTIVES

This study sought to test the hypothesis that thrombus removal, with a new manual thrombus-aspirating device, before primary percutaneous coronary intervention (PPCI) may improve myocardial reperfusion compared with standard PPCI in patients with ST-segment elevation acute myocardial infarction (STEMI).

BACKGROUND

In STEMI patients, PPCI may cause thrombus dislodgment and impaired microcirculatory reperfusion. Controversial results have been reported with different systems of distal protection or thrombus removal.

METHODS

One-hundred forty-eight consecutive STEMI patients, admitted within 12 h of symptom onset and scheduled for PPCI, were randomly assigned to PPCI (group 1) or manual thrombus aspiration before standard PPCI (group 2). Patients with cardiogenic shock, previous infarction, or thrombolytic therapy were excluded. Primary end points were complete (>70%) ST-segment resolution (STR) and myocardial blush grade (MBG) 3.

RESULTS

Baseline clinical and angiographic characteristics were similar in the 2 groups. Comparing groups 1 and 2: complete STR 50% versus 68% (p < 0.05); MBG-3 44% versus 88% (p < 0.0001); coronary Thrombolysis In Myocardial Infarction (TIMI) flow grade 3 78% versus 89% (p = NS); corrected TIMI frame count 21.5 +/- 12 versus 17.3 +/- 6 (p < 0.01); no reflow 15% versus 3% (p < 0.05); angiographic embolization 19% versus 5% (p < 0.05); direct stenting 24% versus 70% (p < 0.0001); and peak creatine kinase-mass band fraction 910 +/- 128 mug/l versus 790 +/- 132 mug/l (p < 0001). In-hospital clinical events were similar in the 2 groups. After adjusting for confounding factors, multivariate analysis showed thrombus aspiration to be an independent predictor of complete STR and MBG-3.

CONCLUSIONS

Manual thrombus aspiration before PPCI leads to better myocardial reperfusion and is associated with lower creatine kinase mass band fraction release, lower risk of distal embolization, and no reflow compared with standard PPCI. (Thrombus Aspiration Before Standard Primary Angioplasty Improves Myocardial Reperfusion in Acute Myocardial Infarction; http://clinicaltrials.gov/ct/show/NCT00257153).

Delivery of primary percutaneous coronary intervention for the management of acute ST segment elevation myocardial infarction: summary of the Cardiac Care Network of Ontario Consensus Report

Tremendous debate has developed over the efficacy of primary percutaneous coronary intervention (PCI) compared with fibrinolysis as the preferred treatment for acute ST segment elevation myocardial infarction (STEMI). In 2002, the Ontario Ministry of Heath and Long-Term Care commissioned the Cardiac Care Network of Ontario to develop consensus recommendations regarding the provincial coordination and provision of urgent PCI for STEMI patients. The panel's work has provided important insights into the acute treatment of STEMI that may be useful to other jurisdictions and may provide a reference for other regions considering the implementation of primary PCI for the management of STEMI patients in their community. In the present report, the evidence for primary PCI is reviewed, the important barriers to implementing this strategy are summarized and several recommendations and models of care for the delivery of primary PCI for STEMI on a wide scale are presented.