Resveratrol Attenuates Ventricular Arrhythmias and Improves the Long-Term Survival in Rats with Myocardial Infarction

Objective  The effects of resveratrol treatment on ventricular arrhythmia, survival, and late cardiac remodeling were evaluated in rats with myocardial infarction (MI). Methods  Three groups of rats (sham-operated, MI, and MI pre-treated with resveratrol) were treated in an in vivo MI model by ligation of left anterior descending coronary artery. The electrocardiogram signals were monitored and recorded for 24 h using an implanted telemetry transmitter. The incidence of ventricular arrhythmias during the first 24-h after MI was also evaluated. Meanwhile, invasive in vivo electrophysiology with pacing in the right ventricle was performed in each group to assess the inducibility of ventricular arrhythmias. Results  Administration of resveratrol significantly suppressed the MI-induced ventricular tachycardia and ventricular fibrillation (0.4 ± 0.2 in Resv group vs. 7.1 ± 2.2 in MI group episodes per hour per rat, P < 0.01). Data also showed that the incidence of inducible ventricular tachycardia was lower in the Resv group than the MI group (46% vs. 81%, P < 0.01). The infarct size and mortality in the Resv group at 14 weeks were reduced by 20% and 33%, respectively, compared with the MI groups. Results from patch clamp recording revealed that resveratrol inhibited L-type calcium current (I _Ca-L), and selectively enhanced ATP-sensitive K⁺ current (I _K,ATP) in a concentration-dependent manner. Conclusion  These results suggested that the emerging anti-arrhythmic character induced by resveratrol treatment in rat hearts could be mainly accounted for by inhibition of I _Ca-L and enhancement of I _K,ATP. Administration of resveratrol also improved the long-term survival by suppressing left ventricular remodeling. You-Ren Chen and Fang-Fang Yi contributed equally to this work.     

Pharmacologic Reperfusion Therapy for Acute Myocardial Infarction

Acute myocardial infarction (MI) remains a significant problem in terms of morbidity, mortality and healthcare costs. Pharmacologic reperfusion therapies for MI are becoming increasingly complex. This review therefore places contemporary pharmacologic MI developments into perspective. An historical overview of pharmacologic reperfusion therapy for MI is provided, followed by an analysis of current limitations, treatment options, and present and likely future pharmacologic therapies. Adjunctive percutaneous and other treatments are also discussed, to clarify what is becoming a rapidly changing field.     

Chronic Metformin Treatment is Associated with Reduced Myocardial Infarct Size in Diabetic Patients with ST-segment Elevation Myocardial Infarction

Purpose

Increased myocardial infarct (MI) size is associated with higher risk of developing left ventricular dysfunction, heart failure and mortality. Experimental studies have suggested that metformin treatment reduces MI size after induced ischaemia but human data is lacking. We aimed to investigate the effect of metformin on MI size in patients presenting with an acute MI.

Methods

All consecutive patients (n?=?3,288) presenting to our hospital with ST-segment elevation myocardial infarction (STEMI) undergoing primary PCI between January 2004 and December 2010 were included in this retrospective analysis. Patients with diabetes were divided according to metformin versus non-metformin based pharmacotherapy. MI size was estimated using peak values of serum creatine kinase (CK), myocardial band of CK (CK-MB), and troponin-T.

Results

We identified 677 (20.6 %) patients with diabetes, of whom 189 (27.9 %) were treated with metformin. Chronic metformin treatment was associated with lower peak levels of CK (1,101 vs. 1,422 U/L, P?=?0.005), CK-MB (152 vs. 182 U/L, P?=?0.018) and troponin-T (2.5 vs. 4.0 ng/L, P?=?0.021) compared to non-metformin using diabetics. After adjustment for age, sex, TIMI flow post PCI, and previous MI, the use of metformin treatment remained an independent predictor of smaller MI size. Patient with diabetes treated with metformin had even smaller MI size than patients without diabetes.

Conclusions

Chronic metformin treatment is associated with reduced MI size compared to non-metformin based strategies in diabetic patients presenting with STEMI. Metformin might have additional beneficial effects beyond glucose lowering efficacy.     

Hypokalemia and Ventricular Arrhythmias in Acute Myocardial Infarction

ABSTRACT Thirty-seven patients with a supine systolic blood pressure >160 and/or a diastolic blood pressure >95 mmHg were enrolled in the study and treated for 6 months with prazosin and 6 months with metoprolol (in random order). Neither the systolic nor the diastolic blood pressures differed after the two types of treatment (median difference 0/0 mmHg). The mean and median differences in serum cholesterol, however, were 0.4 and 0.3 mmol/l respectively, which were 9 and 5% of the pretreatment values. The corresponding differences in the atherogenic index (in which cholesterol in high density lipoproteins is integrated) were 10 and 8% of the pretreatment values. This difference in the metabolic response to the two drugs at the same blood pressure level is most probably of importance in the long-term prevention of ischaemic heart disease, for which high levels of serum cholesterol and atherogenic index are major risk factors.     

Clinical Characteristics and Prevalence of Early Repolarization Associated With Ventricular Arrhythmias Following Acute ST-Elevation Myocardial Infarction

Early repolarization (ER) on a 12-lead electrocardiogram has recently been associated with ventricular tachyarrhythmias (VTAs) in patients without structural heart disease and in patients with healed myocardial infarction (MI). An association between ER and VTAs in the setting of acute ST-segment elevation MI (STEMI) has not been explored. In a single-center retrospective case-control design, 50 patients with STEMI complicated by VTAs (cases), defined as ventricular fibrillation, sustained ventricular tachycardia, or nonsustained ventricular tachycardia within 72 hours of the index hospitalization, were matched for age and gender with 50 subjects with STEMI without VTAs (controls). Electrocardiograms obtained an average of 1 year before STEMI were analyzed for ER pattern, defined as notching or slurring of the terminal QRS complex or J-point elevation >0.1 mV above baseline in ≥2 contiguous leads. A higher prevalence of ER was associated with VTAs overall in cases compared to controls (26% vs 4%, p = 0.01) and localized to anterior (16% vs 0%) and inferior (14% vs 2%, p = 0.07) leads but not lateral limb leads. Notching (10% vs 2%, p = 0.1) and J-point elevation (16% vs 0%) were more common in cases. Slurring was uncommon. ER was associated with VTAs (odds ratio [OR] 6.5, 95% confidence interval [CI] 1.5 to 28.8, p = 0.01), even after adjustment for creatine kinase-MB (OR 9.2, 95% CI 1.6 to 53.4, p = 0.01) and ejection fraction (OR 5.7, 95% CI 1.2 to 27.1, p = 0.03). In conclusion, ER is associated with VTAs in patients with STEMI even after adjustment for left ventricular ejection fraction or creatine kinas-MB levels. Larger prospective studies exploring potential associations and mechanisms of ventricular arrhythmogenesis with ER pattern are needed.     

急性心肌梗死再灌注心律失常的临床特点研究

目的探讨急性心肌梗死患者行急诊经皮冠状动脉介入(PCI)或经皮冠状动脉成行(PTCA)术再灌注心律失常的临床特点。方法对我科2008年1月—2012年3月78例急诊PCI和10例急诊PTCA患者的资料进行回顾性分析,分析急性心肌梗死患者在行急诊PCI或PTCA时再灌注心律失常的发生情况、采取的相关处理方法及最终心律失常的转归,以便于掌握再灌注心律失常的特点,达到降低急诊PCI术的病死率。结果本组发生再灌注心律失常68例(其中室性心律失常52例,缓慢性心律失常16例),再灌注心律失常发生率为77.2%。88例患者梗死相关动脉经血运重建血管均再通,其中行PCI(PTCA+STENT)术76例,单纯行PTCA术12例;死亡1例,是支架后无复流发生所致。结论急诊PCI术时再灌注心律失常发生率较高,特别要警惕室性心律失常及严重的缓慢性心律失常的发生,在术前已有心律失常患者要给与相关药物应用,对于下壁心肌梗死患者术前已有缓慢性心律失常者,应给予安装临时起搏器保护。     

Invasive Approaches in the Management of Cocaine-Associated Non–ST-Segment Elevation Myocardial Infarction

ObjectivesThe aim of this study was to determine the impact of invasive approaches and revascularization in patients with cocaine-associated non–ST-segment elevation myocardial infarction (NSTEMI).BackgroundThe role of invasive approaches in cocaine-associated NSTEMI is uncertain.MethodsThis retrospective cohort study identified 3,735 patients with NSTEMI and history of cocaine use from the Nationwide Readmissions Database from 2016 to 2017. Invasive approaches were defined as coronary angiography, percutaneous coronary intervention (PCI), and coronary artery bypass grafting (CABG). Revascularization was defined as PCI and CABG. The primary efficacy outcome was major adverse cardiac events (MACE), and the primary safety outcome was emergent revascularization. Nonadherence was identified using appropriate International Classification of Diseases-Tenth Revision codes. Two propensity-matched cohorts were generated (noninvasive vs. invasive and noninvasive vs. revascularization) through multivariate logistic regression.ResultsIn the propensity score–matched cohorts, an invasive approach (hazard ratio [HR]: 0.72; 95% confidence interval [CI]: 0.56 to 0.92; p = 0.008) and revascularization (HR: 0.54; 95% CI: 0.40 to 0.73; p < 0.001) (compared with a noninvasive approach) were associated with a lower rate of MACE, without an increase in emergent revascularization. On stratification, PCI and CABG individually were associated with a lower rate of MACE. Emergent revascularization was increased with PCI (HR: 1.78; 95% CI: 1.12 to 2.81; p = 0.014) but not with CABG. Nonadherent patients after PCI and CABG did not have significant difference in rate of MACE. PCI in nonadherent patients was associated with an increase in emergent revascularization (HR: 4.45; 95% CI: 2.07 to 9.57; p < 0.001).ConclusionsInvasive approaches and revascularization for cocaine-associated NSTEMI are associated with lower morbidity. A history of medical nonadherence was not associated with a difference in morbidity but was associated with an increased risk for emergent revascularization with PCI.     

心脏自主神经重构与心肌梗死后室性心律失常

心肌梗死后心脏不同区域出现不同程度的去迷走神经支配、去交感神经支配以及交感神经过度再生。这种心脏自主神经的不均一重构加重了心肌梗死后心肌的电生理异质性,导致了室性心律失常易感性增加。多种针对自主神经重构的治疗手段可以有效预防及治疗心肌梗死后患者的室性心律失常,具有较大的临床应用前景。     

Hypokalemia,Arrhythmias and Early Prognosis in Acute Myocardial Infarction

ABSTRACT Serum potassium concentration was estimated on admission to hospital in 289 women and 785 men with acute myocardial infarction. The proportion of women in potassium subgroups was inversely related to serum potassium concentration, increasing from 8% at serum potassium ≥5.2 mmol/1 to 58% at ≤3 mmol/1. The frequency of diuretic therapy was also higher in women (35%) than in men (23%). The mortality rate was high at 3 months in patients with one or more arrhythmias (atrioventricular block grade 2, complete heart block, bundle branch block, atrial fibrillation, premature ventricular contractions, ventricular tachycardia) detected by conventional methods during the first 48 hours after admission. Hypokalemia (serum potassium ≤3.5 mmol/1) did not significantly predict increased occurrence of any of these arrhythmias. Small inhomogeneities of arrhythmias between the potassium groups may have been caused by digitalis therapy prior to admission. Hypokalemia on admission did not predict altered prognosis during the first 3 months.     

冠心病心肌梗死后室性心律失常经射频导管消融的进展

冠心病心肌梗死后室性心律失常包括急性和陈旧性心肌梗死后的室性心律失常,可导致心功能恶化、猝死、生活质量下降等不良后果,近年来由于对其发病机制的进一步了解,同时在应用心脏三维标测系统引导心肌梗死后室性心律失常的标测和消融、经心外膜标测和消融室性心律失常和应用盐水灌注导管消融等方面有很大进展,心肌梗死后室性心律失常的经射频导管消融已取得较好效果。     

The Role of Myocardial Anisotropy in Arrhythmogenesis Associated with Myocardial Ischemia and Infarction

Myocardial Anisotropy in Ischemia and Infarction . Anisotropy is defined as any property of a system that differs depending on the direction in which it is measured. In the heart, the structure of the cardiac myocytes and their electrical coupling via gap junctions confer an anisotropy in the intracellular resistance to current flow in myocardial tissue. This in turn is responsible for anisotropy in conduction in which the velocity and uniformity of impulse conduction is dependent on its direction relative to the normal myocardial fiber orientation and any underlying pathological nonuniformities in cell orientation and coupling. How cells are coupled also influences refractoriness and excitability. Recent experimental evidence has implicated uniform and nonuniform myocardial anisotropy as important substrates that play a role in the initiation and maintenance of arrhythmias in the setting of ischemia and infarction. These studies may provide a focus for the development of new antiarrhythmic modalities that depend on the modulation of cell electrical coupling.