Peri-procedural myocardial injury during percutaneous coronary intervention: an important target for cardioprotection

Definitions of periprocedural myocardial infarction as surrogates for catheterization laboratory quality or clinical trial end points

A consensus on what constitutes a clinically meaningful periprocedural myocardial infarction (PMI) remains highly debated. We evaluated the accuracy of 2 PMI definitions currently implemented for quality outcome assessment and clinical trial end points. Patients who underwent elective percutaneous coronary intervention with normal baseline troponin-I and creatine kinase-MB were included. PMI was defined according to either the 2007 Task Force (National Cardiovascular Database Registry [NCDR] CathPCI Registry) definition or the updated 2012 Task Force definition. Multivariate analysis was performed for the end point of 1-year all-cause death or myocardial infarction (MI). Of the 7,333 patients included, 31.9% and 2.1% were identified as having a PMI by NCDR or 2012 definition, respectively. Mean age was 66±11 years; 66.8% were men, 1.4±0.9 stents implanted per patient, 84.5% bivalirudin use, and 29.7 type C lesions. Death or MI occurred in 5.6% of NCDR and 6.6% of 2012 defined patients. Neither biomarker was independently associated with death or MI for either definition (NCDR odds ratio 1.1, 95% confidence interval 0.9 to 1.5, p=0.34; 2012 Task Force odds ratio 1.4, 95% confidence interval 0.7 to 3.0, p=0.38). Only a modest correlation exists for either definition to predict death or MI, which did not improve for the 2012 definition. In conclusion, PMI definitions currently used for catheterization lab quality metrics and those used for clinical trial end points have poor discrimination for adverse events. Although the 2012 definition drastically reduced the number of PMIs defined, it did not decrease the predictive accuracy over the NCDR definition.

Impact of the angiographic mechanisms underlying periprocedural myocardial infarction after drug-eluting stent implantation

Periprocedural myocardial infarction (MI) can be induced by several angiographic mechanisms. However, there are limited data on whether these mechanisms differentially affect clinical outcomes. The purpose of our study was to investigate the impact of periprocedural MI on mortality according to the underlying angiographic mechanisms after drug-eluting stent (DES) implantation. We pooled the databases from 7 coronary stent trials using DES. Periprocedural MI was classified according to its underlying angiographic mechanisms as type 1 (due to side-branch occlusion), type 2 (due to other angiographic complications), or type 3 (without angiographically identifiable causes). Among 10,889 patients treated with DES, 768 (7.1%) experienced periprocedural MI; 463 cases (60.3%) were driven by type 1 cause, 138 (18.0%) by type 2 cause, and 167 (21.7%) by type 3 cause. Mortality rates at 2 years were higher in patients with periprocedural MI than in those without (3.5% vs 2.1%, respectively). Significant differences in mortality were observed according to the angiographic mechanisms of MI (type 1: 2.8% vs type 2: 6.1% vs type 3: 3.1%). After multivariable adjustment, type 2 MI was significantly associated with an increased risk of mortality (hazard ratio 2.65, 95% confidence interval 1.77 to 3.96), whereas type 1 and type 3 MI were not related with increased mortality. In conclusion, among patients receiving DES implantation, periprocedural MI was associated with increased mortality, and there were differential associations with mortality according to the underlying angiographic mechanisms.

Remote ischemic postconditioning during percutaneous coronary interventions: remote ischemic postconditioning-percutaneous coronary intervention randomized trial

BACKGROUND

Remote ischemic preconditioning may result in reduction in infarct size during percutaneous coronary intervention (PCI). It is unclear whether remote ischemic postconditioning (RIPost) will reduce the incidence of myocardial injury after PCI, and whether ischemic conditioning of a larger remote organ (thigh versus arm) would provide further myocardial protection.

METHODS AND RESULTS

We randomized 360 patients presenting with stable or unstable angina (28% of patients) and negative Troponin T at baseline to 3 groups: 2 groups received RIPost (induced by ischemia to upper or lower limb), and a third was the control group. RIPost was applied during PCI immediately after stent deployment, by three 5-minute cycles of blood pressure cuff inflation to >200 mm Hg in the arm or thigh (20 mm Hg in the control) with 5-minute breaks between each cycle. The primary end-point was the proportion of patients with Troponin T levels >3×ULN postprocedure (at 6 or 18-24 hours), where ULN stands for upper limit of normal. A total of 120 patients were randomized to each group. There were no differences in baseline characteristics between the 3 groups. The primary outcome occurred in 30%, 35%, and 35% of the arm, thigh, and control groups, respectively (P=0.64). There were no differences in creatine kinase or high sensitivity C-reactive protein levels after PCI or in the incidence of acute kidney injury between the groups.

CONCLUSIONS

RIPost during PCI did not reduce the incidence of periprocedural myocardial injury. Similar effect was obtained when remote ischemia was induced to the upper or lower limb.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00970827.

Can a high reloading dose of atorvastatin prior to percutaneous coronary intervention reduce periprocedural myocardial infarction?

BACKGROUND

Periprocedural myocardial infarction (MI) is a common complication following percutaneous coronary intervention (PCI) and statins have been shown to reduce MI in statin-naïve patients. We aimed to identify whether a high reloading dose of atorvastatin can prevent MI following PCI in patients who were already being treated with statins.

MATERIAL AND METHODS

In this triple-blind controlled randomized clinical trial, 190 candidates for elective PCI, who were already using statins and/or other lipid lowering agents such as fibrates, were randomly assigned to two equal groups to receive either atorvastatin (80 mg) or placebo within 24 hours before the procedure. Serum levels of creatinine kinase myocardial isoenzyme (CK-MB), cardiac troponin I (cTNI) and high-sensitive C-reactive protein (hs-CRP) were measured at baseline and then 6 and 12 hours following PCI. Post-procedural MI was defined as troponin elevation>5-fold in patients with normal baseline or >20% in those with elevated baseline measurements with or without chest pain or ST segment or T wave abnormalities.

RESULTS

Frequency of MI in the atorvastatin group was 3 (3.1%) vs. 10 (10.5%) in the placebo group (p=0.04). The CK-MB rise within 6 hours following PCI was 0.6±0.3 mg/dl in the intervention group versus 3.0±1.6 mg/dl in the placebo group. Also, the levels of cTNI within 6 and 12 hours in the intervention group was significantly lower than the placebo group (p=0.01 and 0.008, respectively). hs-CRP was significantly lower in the intervention group after 12 hours (p=0.004).

CONCLUSION

Administration of a high reloading dose of atorvastatin within 24 hours before PCI could significantly reduce the frequency of periprocedural MI. CLINICAL TRIAL REGISTRATION CODE: IRCT201205209768N1.

The emerging role of TRα1 in cardiac repair: potential therapeutic implications

Thyroid hormone (TH) is critical for adapting living organisms to environmental stress. Plasma circulating tri-iodothyronine (T3) levels drop in most disease states and are associated with increased oxidative stress. In this context, T3 levels in plasma appear to be an independent determinant for the recovery of cardiac function after myocardial infarction in patients. Thyroid hormone receptor α1 (TRα1) seems to be crucial in this response; TRα1 accumulates to cell nucleus upon activation of stress induced growth kinase signaling. Furthermore, overexpression of nuclear TRα1 in cardiomyocytes can result in pathological or physiological growth (dual action) in absence or presence of its ligand, respectively. Accordingly, inactivation of TRα1 receptor prevents reactive hypertrophy after myocardial infarction and results in heart failure with increased phospholamban (PLB) expression and marked activation of p38MAPK. In line with this evidence, TH is shown to limit ischemia/reperfusion injury and convert pathologic to physiologic growth after myocardial infarction via TRα1 receptor. TRα1 receptor may prove to be a novel pharmacological target for cardiac repair/regeneration therapies.

Positive association of coronary calcium detected by computed tomography coronary angiography with periprocedural myocardial infarction

BACKGROUND

Periprocedural myocardial infarction (PMI) may occur in approximately 5% to 30% of patients undergoing percutaneous coronary intervention. Whether the morphology of coronary plaque calcium affects the occurrence of PMI is unknown.

MATERIALS AND METHODS

A total of 616 subjects with stable angina and normal baseline cardiac troponin I levels who had undergone computed tomography angiography (CTA) were referred to elective percutaneous coronary intervention. The morphology of coronary calcium was determined by CTA analysis. PMI was defined as an elevation in 24-h post-procedural cardiac troponin I levels of > 5 times the upper limit of normal with either symptoms of myocardial ischemia, new ischemic electrocardiographic changes, or documented complications during the procedure. Logistic regression was performed to identify the effect of the morphology of coronary calcium on the occurrence of PMI.

RESULTS

According to the presence or morphology of coronary calcium as shown by CTA, 210 subjects were grouped in the heavy calcification group, 258 in the mild calcification group, 40 in the spotty calcification group and 108 in the control group. The dissection rate was significantly higher in the heavy calcification group than in the control group (7.1 % vs. 1.9%, p = 0.03). The occurrence of PMI in the heavy calcification group was significantly higher than that in the control group (OR 4.38, 95% CI 1.80-10.65, p = 0.001). After multivariate adjustment, the risk of PMI still remained significantly higher in the heavy calcification group than in the control group (OR 4.04, 95% CI 1.50-10.89, p = 0.003).

CONCLUSIONS

The morphology of coronary calcium determined by CTA may help to predict the subsequent occurrence of PMI. A large amount of coronary calcium may be predictive of PMI.

The role of monocyte phenotype switching in peri-procedural myocardial injury and its involvement in statin therapy

Peri-procedural myocardial injury, which is associated with worse long-term clinical outcome, is a common complication related to inflammatory pathogenetic mechanisms. Monocytes and macrophages play key roles in the initiation and progression of atherosclerosis. Recent studies have demonstrated that monocytes in human peripheral blood are heterogeneous, including CD14⁺CD16⁻ monocytes and CD14⁺CD16⁺ monocytes. Several lines of evidence suggested that CD14⁺CD16⁺ monocytes might contribute to the accelerated atherosclerosis. In view of the heightened appreciation of the heterogeneity of circulating monocytes, we hypothesized that an up-shifting subset of CD14⁺CD16⁺ monocytes might be induced by percutaneous coronary intervention (PCI), which subsequently leads to peri-procedural myocardial injury. Moreover, statins loading before PCI could exert anti-inflammatory effects partly by modulating monocyte phenotype and thus prevent peri-procedural myocardial injury.

Soluble lectin-like oxidized low density lipoprotein receptor-1 as a biochemical marker for atherosclerosis-related diseases

Lectin-like oxidized low density lipoprotein receptor-1 (LOX-1), the main oxidized low-density lipoprotein (OxLDL) in endothelial cells, is upregulated in atherosclerotic lesions and is involved in several cellular processes that regulate the pathogenesis of atherosclerosis. The LOX-1 expressed on the cell surface can be proteolytically cleaved and released in a soluble form (sLOX-1) in the circulation under pathological conditions. Serum levels of sLOX-1, in fact, are elevated at the early stages of acute coronary syndrome and are associated with coronary plaque vulnerability and with the presence of multiple complex coronary lesions. Moreover, in subjects with stable CAD, levels of serum sLOX-1 are associated with the presence of lesions in the proximal and mid-segments of the left anterior descending artery that are the most prone to rupture; in subjects undergoing percutaneous coronary intervention, baseline preprocedural serum sLOX-1 levels are associated with the incidence of periprocedural myocardial infarction. Altogether, these findings suggest that circulating levels of sLOX-1 might be a diagnostic and prognostic marker for atherosclerotic-related events.

Influence of platelet reactivity and inflammation on peri-procedural myonecrosis in East Asian patients undergoing elective percutaneous coronary intervention

BACKGROUND AND OBJECTIVES

The contribution of multiple risk factors to peri-procedural myocardial infarction (PMI) in East Asians remains controversial. To assess the influence of clinical or laboratory covariates on PMI in these patients.

METHODS

Stable patients (n=341) undergoing elective percutaneous coronary intervention (PCI) were enrolled. Platelet reactivity was measured by conventional aggregometry and VerifyNow. Inflammation markers and lipid profile were determined by standard methods. PMI was defined according to Universal definition (troponin I or CK-MB ≥ 3 times the 99th percentile of the upper reference limit).

RESULTS

PMI (defined by troponin I and CK-MB) occurred in 47 (13.8%) and 30 (8.8%) patients, respectively. There was no significant difference in ADP-induced platelet reactivity between patients with vs. without PMI. Patients with PMI (troponin I) had higher levels of 6 μg/mL collagen-induced platelet aggregation (PA) and VerifyNow 'BASE' compared with those without PMI. The combination of '6 μg/mL collagen-induced PA>40%'+'BASE>318' (odds ratio, 14.08; 95% confidence intervals, 1.68 to 111.11; p=0.015) or 'WBC>6550/mm(3)'+'C-reactive protein>2.3mg/L' (odds ratio, 7.75; 95% confidence intervals, 2.49 to 24.39; p<0.001) was associated with an increased risk of PMI (troponin I). The greatest likelihood ratio was observed when cholesterol, inflammation marker and platelet function were combined together.

CONCLUSION

This is the first study to demonstrate that heightened platelet responsiveness to collagen and thrombin may be a risk factor for myonecrosis in patients undergoing elective PCI. The utility of the combining measures of platelet function, inflammation and cholesterol to enhance risk stratification and thus facilitate personalized therapy deserves further study.

Myxomavirus-derived serpin prolongs survival and reduces inflammation and hemorrhage in an unrelated lethal mouse viral infection

Lethal viral infections produce widespread inflammation with vascular leak, clotting, and bleeding (disseminated intravascular coagulation [DIC]), organ failure, and high mortality. Serine proteases in clot-forming (thrombotic) and clot-dissolving (thrombolytic) cascades are activated by an inflammatory cytokine storm and also can induce systemic inflammation with loss of normal serine protease inhibitor (serpin) regulation. Myxomavirus secretes a potent anti-inflammatory serpin, Serp-1, that inhibits clotting factor X (fX) and thrombolytic tissue- and urokinase-type plasminogen activators (tPA and uPA) with anti-inflammatory activity in multiple animal models. Purified serpin significantly improved survival in a murine gammaherpesvirus 68 (MHV68) infection in gamma interferon receptor (IFN-γR) knockout mice, a model for lethal inflammatory vasculitis. Treatment of MHV68-infected mice with neuroserpin, a mammalian serpin that inhibits only tPA and uPA, was ineffective. Serp-1 reduced virus load, lung hemorrhage, and aortic, lung, and colon inflammation in MHV68-infected mice and also reduced virus load. Neuroserpin suppressed a wide range of immune spleen cell responses after MHV68 infection, while Serp-1 selectively increased CD11c(+) splenocytes (macrophage and dendritic cells) and reduced CD11b(+) tissue macrophages. Serp-1 altered gene expression for coagulation and inflammatory responses, whereas neuroserpin did not. Serp-1 treatment was assessed in a second viral infection, mouse-adapted Zaire ebolavirus in wild-type BALB/c mice, with improved survival and reduced tissue necrosis. In summary, treatment with this unique myxomavirus-derived serpin suppresses systemic serine protease and innate immune responses caused by unrelated lethal viral infections (both RNA and DNA viruses), providing a potential new therapeutic approach for treatment of lethal viral sepsis.

Priming adult stem cells by hypoxic pretreatments for applications in regenerative medicine

The efficiency of regenerative medicine can be ameliorated by improving the biological performances of stem cells before their transplantation. Several ex-vivo protocols of non-damaging cell hypoxia have been demonstrated to significantly increase survival, proliferation and post-engraftment differentiation potential of stem cells. The best results for priming cultured stem cells against a following, otherwise lethal, ischemic stress have been obtained with brief intermittent episodes of hypoxia, or anoxia, and reoxygenation in accordance with the extraordinary protection afforded by the conventional maneuver of ischemic preconditioning in severely ischemic organs. These protocols of hypoxic preconditioning can be rather easily reproduced in a laboratory; however, more suitable pharmacological interventions inducing stem cell responses similar to those activated in hypoxia are considered among the most promising solutions for future applications in cell therapy. Here we want to offer an up-to-date review of the molecular mechanisms translating hypoxia into beneficial events for regenerative medicine. To this aim the involvement of epigenetic modifications, microRNAs, and oxidative stress, mainly activated by hypoxia inducible factors, will be discussed. Stem cell adaptation to their natural hypoxic microenvironments (niche) in healthy and neoplastic tissues will be also considered.

Remote ischaemic postconditioning: does it protect against ischaemic damage in percutaneous coronary revascularisation? Randomised placebo-controlled clinical trial

OBJECTIVE

Determine whether remote ischaemic postconditioning (RIP) protects against percutaneous coronary intervention-related myocardial infarction (PCI-MI).

DESIGN

Single-centre, randomised, blinded to the researchers, clinical trial. ClinicalTrials.gov (NCT 01113008).

SETTING

Tertiary hospital centre.

PATIENTS

232 patients underwent elective PCI for stable or unstable angina.

INTERVENTIONS

Patients were randomised to RIP (induction of three 5-min cycles of ischaemia in the arm after the PCI) versus placebo.

MAIN OUTCOME MEASURES

The primary outcome measure was the peak 24-h troponin I level. PCI-MI was defined by an elevation of troponin values >3 or >5 of the 99th percentile according to the classical or the new definition. The secondary outcome measure was hospital admission, PCI for stable angina or acute coronary syndrome and mortality after 1 year of follow-up. The use of RIP in diabetic patients was specifically studied.

RESULTS

The mean age was 64.6 years, and 42% were diabetic. The peak troponin in the RIP patients was 0.476 vs 0.478 ng/mL (p=0.99). PCI-MI occurred in 36% of the RIP patients versus 30.8% in the placebo group (p=0.378). Diabetic RIP patients had more PCI-MI (new definition): OR 2.7; 95% CI 1.10 to 6.92; p=0.027. The secondary outcome measure was seen in 11.7% of the RIP patients versus 10.8% in the placebo group (p=0.907).

CONCLUSIONS

RIP did not reduce the damage associated with elective PCI or cardiovascular events during the follow-up. The diabetic population who underwent RIP had more PCI-MI.

Usefulness of rosuvastatin to prevent periprocedural myocardial injury in patients undergoing elective coronary intervention

The aim of the present study was to investigate whether percutaneous coronary intervention-related periprocedural myocardial infarction (MI) can be suppressed more significantly with high- compared with low-dose rosuvastatin. A total of 232 patients scheduled to undergo elective percutaneous coronary intervention within 5 to 7 days were assigned to groups that would receive either 2.5 or 20 mg/day of rosuvastatin (n = 116 each). The incidence of periprocedural MI did not significantly differ between the high and low-dose groups (8.7% vs 18.7%, p = 0.052). In patients who were not taking statins at the time of enrollment, high-dose rosuvastatin significantly suppressed periprocedural MI compared with the low dose (10.5% vs 30.0%, p = 0.037). The difference was not significant in patients who were already taking statins (high vs low dose 7.6% vs 10.6%, p = 0.582). In conclusion, the incidence of percutaneous coronary intervention-related periprocedural MI was reduced more effectively by high-dose than by low-dose rosuvastatin in statin-naive patients. However, low-dose rosuvastatin is sufficient for patients who are already taking statins.

Ascertainment of any and all neurologic and myocardial damage in carotid revascularization: the key to optimization?

The majority of carotid revascularization procedures performed at present are in asymptomatic patients. Since such procedures convey no immediate benefit, but rather protect from future hazard, optimization of procedural safety is mandatory. The authors focus their discussion on the methodologies that assess periprocedural myocardial damage and brain injury, as used in past clinical trials, from the fields of perioperative medicine and neurovascular imaging, and discuss methodologies to reduce both events in carotid revascularization.

Frequency, causes, predictors, and clinical significance of peri-procedural myocardial infarction following percutaneous coronary intervention

AIMS

Peri-procedural myocardial infarction (MI) is a not infrequent complication of percutaneous coronary intervention (PCI), but conflicting information exists regarding incidence and prognostic impact of this event. We investigated frequency, causes, predictors, and clinical relevance of peri-procedural MI, using a large database.

METHODS AND RESULTS

We pooled individual patient-level data from 11 PCI studies in which peri-procedural creatine kinase-MB mass was routinely measured and mortality data were prospectively collected. Among 23 604 patients from 11 studies, 1677 {7.1% [95% confidence interval (CI) 6.8-7.5%]} had peri-procedural MI. The most common mechanism of peri-procedural MI was side-branch occlusion. Independent predictors of peri-procedural MI were older age, female gender, diabetes, hypertension, renal dysfunction, multivessel disease, left anterior descending artery disease, left main disease, bifurcation lesion, long lesion, drug-eluting stents, and number of stents. Follow-up varied from 1 year to 5 years. In a crude analysis, patients with peri-procedural MI had significantly a higher risk of mortality than those without peri-procedural MI [hazard ratio (HR) 1.47; 95% CI 1.24-1.74]. After adjustment for baseline covariates, peri-procedural MI was associated with an increased risk of mortality (HR 1.20; 95% CI 1.04-1.39).

CONCLUSION

Among patients undergoing PCI, the occurrence of peri-procedural MI measured by CK-MB mass assay was ~7%, and more than half of cases were associated with side-branch occlusion. Several higher risk patients, lesions, and procedural characteristics were independent predictors of peri-procedural MI. Peri-procedural MI was associated with an increase in mortality.

Effect of tailored antiplatelet therapy on periprocedural myonecrosis in patients with diabetes mellitus (from the DM-Verify Now Trial)

We investigated whether additional platelet inhibition with a glycoprotein IIb/IIIa inhibitor would be beneficial in reducing the risk of periprocedural myocardial infarction (PMI) in diabetic patients with high residual platelet reactivity (HPR). Patients with diabetes mellitus were administered aspirin and clopidogrel at a 300-mg loading dose 1 day before the procedure, and the VerifyNow P2Y(12) assay was performed just before percutaneous coronary intervention. Patients with HPR, defined as a P2Y(12) reaction unit of ≥270 were randomly assigned to group A or control group C1. Patients without HPR were assigned to control group C2. Conventional anticoagulation with heparin was given to groups C1 and C2, and group A received additional abciximab treatment. Clinically relevant PMI was defined as any elevation in the biomarkers creatine kinase-MB isoenzyme and cardiac troponin I >3 times the upper normal limit measured 8, 16, or 24 hours after percutaneous coronary intervention. Of the patients, 47 and 51 were assigned to group A and C1; the clinical and procedural characteristics in the 2 groups were balanced. Of the 47 patients in group A and 51 patients in group C1, 9 (19%) and 9 (18%), respectively, experienced a PMI event according to the creatine kinase-MB cutoff (p = 1.00), and 27 in group A (57%) and 29 in group C1 (57%) experienced a PMI event according to the troponin I cutoff (p = 1.00). Five minor bleeding events, including small and localized hematomas, were observed immediately after the procedure (4 in group A and 1 in group C1). Only 1 major bleeding event, retroperitoneal hemorrhage, was observed in group A. The patients in group C2 had a PMI event rate (50% of 32 patients, p = 1.00) similar to that of group C1. In conclusion, additional platelet inhibition using a tailored approach and a point-of-care assay did not improve the periprocedural outcome in diabetic patients with HPR.

Coronary microembolization during early reperfusion: infarct extension, but protection by ischaemic postconditioning

AIMS

Reperfusion injury following acute myocardial infarction impacts not only on the myocardium but also on the coronary microcirculation, and microembolization from the culprit lesion contributes to microvascular obstruction. Prior experimental studies have not accounted for microembolization in ischaemia/reperfusion injury and not considered microembolization as a confounder and target of protection by ischaemic postconditioning. We therefore investigated the impact of microembolization during reperfusion on infarct size and cardioprotection by postconditioning.

METHODS AND RESULTS

Anaesthetized, open-chest pigs were subjected to 90 min low-flow ischaemia. Immediate full reperfusion (n = 8) served as the control. Microembolization was induced by intracoronary infusion of 42 µm microspheres with the onset of reperfusion (n = 8). In a second step, postconditioning was induced by six cycles of 20s reperfusion/20s re-occlusion without (n = 8) and with superimposed microembolization (n = 8). Transmural blood flow and area at risk were determined by radioactive microspheres, infarct size by triphenyl tetrazolium chloride staining. Area at risk and transmural blood flow were not different between groups. Microembolization increased infarct size from 32 ± 3% of the area at risk to 47 ± 3% (P < 0.05). Embolizing particles were re-distributed away from the central infarcted area and accumulated in the infarct border, thus contributing to infarct extension. Postconditioning reduced infarct size without (21 ± 3%; P < 0.05 vs. immediate full reperfusion) and also with additional microembolization (26 ± 5%; P < 0.05 vs. immediate full reperfusion and microembolization); embolizing particles did not accumulate in the infarct border.

CONCLUSION

Microembolization at reperfusion augments infarct size, but postconditioning in the presence of microembolization still reduces infarct size and attenuates infarct expansion.

The index of microcirculatory resistance predicts myocardial infarction related to percutaneous coronary intervention

BACKGROUND

Periprocedural myocardial infarction (MI) occurs in a significant proportion of patients undergoing percutaneous coronary intervention (PCI) and portends poor outcomes. Currently, no clinically applicable method predicts periprocedural MI in the cardiac catheterization laboratory before it occurs. We hypothesized that impaired baseline coronary microcirculatory reserve, which reduces the ability to tolerate ischemic insults, is a risk for periprocedural MI and that the index of microcirculatory resistance (IMR) measured during PCI can predict occurrence of periprocedural MI.

METHODS AND RESULTS

Consecutive patients undergoing elective PCI of a single lesion in the left anterior descending coronary artery were recruited. A pressure-temperature sensor wire was used to measure IMR before PCI. Of the 50 patients studied, 10 had periprocedural MI. From binary logistic regression analyses of all clinical, procedural, and physiological parameters, univariable predictors of periprocedural MI were pre-PCI IMR (P=0.003) and the number of stents used (P=0.039). Pre-PCI IMR was the only independent predictor in bivariable regression analyses performed by adjusting for each available covariate one at a time (all P≤0.02). Pre-PCI IMR ≥27 U had 80.0% sensitivity and 85.0% specificity for predicting periprocedural MI (C statistic, 0.80; P=0.003). Pre-PCI IMR ≥27 U was independently associated with a 23-fold risk of developing periprocedural MI (odds ratio, 22.7; 95% CI, 3.8-133.9).

CONCLUSIONS

These data suggest that the status of the coronary microcirculation plays a role in determining susceptibility toward periprocedural MI at the time of elective PCI. The IMR can predict subsequent risk of developing myocardial necrosis and may guide adjunctive prevention strategies.

Prevention of postoperative atrial fibrillation: novel and safe strategy based on the modulation of the antioxidant system

Postoperative atrial fibrillation (AF) is the most common arrhythmia following cardiac surgery with extracorporeal circulation. The pathogenesis of postoperative AF is multifactorial. Oxidative stress, caused by the unavoidable ischemia-reperfusion event occurring in this setting, is a major contributory factor. Reactive oxygen species (ROS)-derived effects could result in lipid peroxidation, protein carbonylation, or DNA oxidation of cardiac tissue, thus leading to functional and structural myocardial remodeling. The vulnerability of myocardial tissue to the oxidative challenge is also dependent on the activity of the antioxidant system. High ROS levels, overwhelming this system, should result in deleterious cellular effects, such as the induction of necrosis, apoptosis, or autophagy. Nevertheless, tissue exposure to low to moderate ROS levels could trigger a survival response with a trend to reinforce the antioxidant defense system. Administration of n-3 polyunsaturated fatty acids (PUFA), known to involve a moderate ROS production, is consistent with a diminished vulnerability to the development of postoperative AF. Accordingly, supplementation of n-3 PUFA successfully reduced the incidence of postoperative AF after coronary bypass grafting. This response is due to an up-regulation of antioxidant enzymes, as shown in experimental models. In turn, non-enzymatic antioxidant reinforcement through vitamin C administration prior to cardiac surgery has also reduced the postoperative AF incidence. Therefore, it should be expected that a mixed therapy result in an improvement of the cardioprotective effect by modulating both components of the antioxidant system. We present novel available evidence supporting the hypothesis of an effective prevention of postoperative AF including a two-step therapeutic strategy: n-3 PUFA followed by vitamin C supplementation to patients scheduled for cardiac surgery with extracorporeal circulation. The present study should encourage the design of clinical trials aimed to test the efficacy of this strategy to offer new therapeutic opportunities to patients challenged by ischemia-reperfusion events not solely in heart, but also in other organs such as kidney or liver in transplantation surgeries.

Risk of target lesion failure in relationship to vessel angiographic geometry and stent conformability using the second generation of drug-eluting stents

BACKGROUND

Vessel angulation and large changes in vessel geometry after stent implantation have been associated with an increased risk of target lesion failure (TLF) using bare-metal stents. Second-generation drug-eluting stents (DES)offer superior conformability and inhibition of neointima. The aim of the study is to investigate the relationship between pre and post-implant vessel geometry and the occurrence of TLF at 1 year after treatment with second-generation DES; and to compare the conformability of Resolute and Xience stents.

METHODS

The RESOLUTE All-Comers trial randomized 2292 patients (3366 lesions) to Resolute zotarolimus-DES (Medtronic CardioVascular) or Xience everolimus-DES (Abbott Vascular). At 1 year, 176 lesions (121 patients)presented with TLF; a composite of cardiac death, acute myocardial infarction (AMI) and target lesion revascularization (TLR). Lesions with TLF were matched with 176 lesions (168 patients) without TLF adjusting for clinical and procedural characteristics. The number of bends, vessel curvature and angulation were assessed with quantitative coronary angiography pre and post-implantation. The absolute difference post minus pre-implantation was used as a surrogate of stent conformability.

RESULTS

At pre-implantation, lesions without and with TLF had similar numbers of bends/lesion (1.81 vs 1.74; P = .35), vessel curvature (0.295 cm(-1) vs 0.363 cm(-1); P = .13) and vessel angulation (46.3° vs 43.5°; P = .80), respectively. Lesions without and with TLR also had similar numbers of bends/lesion (1.39 vs 1.39; P = .83), vessel curvature (0.368 cm(-1) vs 0.325 cm(-1); P = .33) and angulation (40.2° vs 37.2°; P = .19). Lesions without and with in-hospital AMI also presented with similar number of bends/lesion (1.69 vs 1.81; P = .48), vessel curvature (0.349 cm(-1) vs 0.345 cm(-1); P = .91) and vessel angulation (43.53° vs 48.45°; P = .38). The absolute difference post- - pre-implantation was similar in lesions without and with TLF, TLR and In-hospital AMI. The absolute difference post- - pre-implantation was similar with both Resolute and Xience in vessel curvature (-0.046 cm(-1) vs -0.047 cm(-1); P = .66) and was smaller in number of bends/lesion (-0.08 vs -0.16; P = .13) and in vessel angulation (-6.0° vs -10.1°; P = .03) with the Resolute.

CONCLUSIONS

Bended, curved, and angulated lesions and changes in the number of bends/lesion, vessel curvature, and angulation from pre to post-implantation have no relation with TLF and TLR at 1 year and have no relation with In-hospital AMI using second-generation of DES. Resolute appears to be more conformable than Xience.

The therapeutic potential of ischemic conditioning: an update

Novel approaches are required to improve clinical outcomes in patients with coronary heart disease (CHD). Ischemic conditioning--the practice of applying brief episodes of nonlethal ischemia and reperfusion to confer protection against a sustained episode of lethal ischemia and reperfusion injury--is one potential therapeutic strategy. Importantly, the protective stimulus can be applied before (ischemic preconditioning) or after (ischemic perconditioning) onset of the sustained episode of lethal ischemia, or even at the onset of myocardial reperfusion (ischemic postconditioning). Furthermore, the protective stimulus can be applied noninvasively by placing a blood-pressure cuff on an upper or lower limb to induce brief episodes of nonlethal ischemia and reperfusion (remote ischemic conditioning), a finding that has greatly facilitated the translation of ischemic conditioning to various clinical settings. In addition to mechanical approaches, elucidation of the signal-transduction pathways underlying ischemic conditioning has identified several novel targets for pharmacological conditioning. This Review highlights findings from proof-of-concept clinical studies conducted in the past 5-6 years, in which the therapeutic potential of ischemic and pharmacological conditioning has been realized. Large, randomized, controlled trials are now required to determine whether pharmacological and ischemic conditioning improve clinical end points and outcomes in patients with CHD.