Risk Stratification and Prevention of Sudden Death in Patients with Heart Failure

T-Wave Analysis on the 24 h Holter ECG Monitoring as a Predictive Assessment of Major Adverse Cardiovascular Events in Patients with Myocardial Infarction: A Literature Review and Future Perspectives

Myocardial ischemia is a pathophysiological state characterized by inadequate perfusion of the myocardium, resulting in an imbalance between myocardial oxygen demand and supply. It is most commonly caused by coronary artery disease, in which atherosclerotic plaques lead to luminal narrowing and reduced blood flow to the heart. Myocardial ischemia can manifest as angina pectoris or silent myocardial ischemia and can progress to myocardial infarction or heart failure if left untreated. Diagnosis of myocardial ischemia typically involves a combination of clinical evaluation, electrocardiography and imaging studies. Electrocardiographic parameters, as assessed by 24 h Holter ECG monitoring, can predict the occurrence of major adverse cardiovascular events in patients with myocardial ischemia, independent of other risk factors. The T-waves in patients with myocardial ischemia have prognostic value for predicting major adverse cardiovascular events, and their electrophysiological heterogeneity can be visualized using various techniques. Combining the electrocardiographic findings with the assessment of myocardial substrate may offer a better picture of the factors that can contribute to cardiovascular death.

Current challenges in sudden cardiac death prevention

Ischemic heart disease and non-ischemic dilated cardiomyopathy are the most common causes of arrhythmic sudden cardiac death (SCD). Implantable cardioverter defibrillator (ICD) therapy is the only strategy that proved to be effective in preventing SCD in high-risk individuals while the role of antiarrhythmic drugs is limited to symptoms relief. Current guidelines recommend selecting candidates to ICD implantation based on etiology, symptoms of heart failure (NYHA class), and severely depressed left ventricular ejection fraction, but these parameters are neither sensitive nor specific. The review addresses the mechanisms of SCD in patients with heart failure of either ischemic or non-ischemic etiology, risk stratification, and strategies for prevention of SCD in the clinical practice (including optimization of heart failure therapy, avoidance of triggering factors, antiarrhythmic drugs, ICD therapy, early resuscitation, and public access defibrillators).

Development of Antiarrhythmic Therapy-Resistant Ventricular Tachycardia, Ventricular Fibrillation, and Premature Ventricular Contractions in a 15-Year-Old Patient

Sudden cardiac arrest (SCA) is the sudden cessation of regular cardiac activity so that the victim becomes unresponsive, with no signs of circulation and no normal breathing. Asystole, ventricular tachycardia (VT), ventricular fibrillation (VF), and pulseless electrical activity are the underlying rhythm disturbances in the pediatric age group. If appropriate interventions (cardiopulmonary resuscitation-CPR and/or defibrillation or cardioversion) are not performed rapidly, this condition progresses to sudden death. There have not been many reported cases of the approach and treatment of cardiac arrhythmias after SCA. Herein, we would like to report a case of a 15-year-old female patient with dilated cardiomyopathy (DCM) who was admitted to our clinic a year ago, and while her left ventricular systolic functions were improved, SCA suddenly occurred. Since the SCA event occurred in another city, intravenous treatment of amiodarone was done immediately and was switch to continuous infusion dose of amiodarone until the patient arrived at our institution's pediatric intensive care unit (PICU) 3 hours later. During the patient's 20-day PICU hospitalization, she developed pulseless VT and VF from time to time. The patient's pulseless VT and VF attacks were brought under control by the use of a defibrillator and added antiarrhythmic drugs (amiodarone, flecainide, esmolol, and propafenone). Intriguingly, therapy-resistance bigeminy with premature ventricular contractions (PVCs) continued despite all these treatments. The patient did not have adequate blood pressure measured by invasive arterial blood pressure monitoring while having bigeminy PVCs. The intermittent bigeminy PVCs ameliorated rapidly after intermittent boluses of lidocaine. In the end, multiple antiarrhythmic therapies and intermittent bolus lidocaine doses were enough to bring her cardiac arrhythmias after SCA under control. This case illustrates that malign PVC's should be taken very seriously, since they may predispose to the development of VT or VF. Also, this case highlights the importance of close vigilance of arterial pressure tracings of patients with bigeminy PVCs which develop after SCA and should not be accepted as normal.

The prognostic impact of myocardial late gadolinium enhancement

Cardiovascular magnetic resonance using late gadolinium enhancement (LGE) provides a unique opportunity to assess myocardial tissue in vivo. LGE enables tissue characterization in ischemic and nonischemic cardiomyopathies and other cardiac diseases. LGE is associated with adverse clinical outcomes across a range of different cardiac conditions and may improve risk stratification for death, sudden cardiac death, or serious adverse events beyond traditional prognostic markers. Generally, matching data for the prognostic impact of LGE are frequently reached in cardiac disorders. In other diseases, only a limited number of trials are available, but it is anticipated that the prognostic impact of delayed enhancement will become evident. The development and validation of new cardiovascular magnetic resonance methods for diffuse myocardial fibrosis measurements would even improve the prognostic impact of LGE. The evaluation of diffuse myocardial fibrosis has a great potential in large-scale diseases, including their initial phases, with the possibility to identify patients at risk for subsequent development of clinical heart failure, to assess repeatedly the stage and progression of cardiac diseases, and to monitor the effect of treatment.

Cardiopulmonary exercise test predicts sustained ventricular arrhythmias in chronic heart failure

BACKGROUND

The cardiopulmonary exercise test (CPX) is an affordable tool for risk prediction in patients with chronic heart failure (CHF). We aimed to determine the role of CPX parameters in predicting the risk of incidence of sustained ventricular arrhythmias (SVA) in CHF.

METHODS

Sixty-one consecutive patients with CHF enrolled in the Daunia Heart Failure Registry underwent CPX and were followed for 327 ± 247 days. Clinical follow-up was performed every month and anticipated in case of re-hospitalisation for cardiac disease. Incidence of SVA was evaluated by direct clinical examination (ECG, ambulatory ECG).

RESULTS

Patients with episodes of SVA (N 14) showed lower values of pVO2 and PetCO2, and higher values of VE/VCO2, VE/VCO2 slope, and VE%. After correction for age, gender, diabetes, ischaemic heart disease and left ventricular ejection fraction, peak VO2 (hazard ratio (HR) 0.68, 95 % confidence interval (CI) 0.51-0.91, p < 0.05), VE% (HR 1.38, 95 % CI 1.04-1.84, p < 0.05), VE/VCO2 (HR 1.38, 95 % CI 1.04-1.82, p < 0.05), VE/VCO2 slope (HR 1.77, 95 % CI 1.31-2.39, p < 0.01), PetCO2 (HR 0.66, 95 % CI 0.50-0.88, p < 0.01) were found as predictors of SVA. At Kaplan-Meier analysis, lower event-free rates were found in subjects with peak VO2 values below median (log rank p < 0.05), values of VE/VCO2 above mean (p < 0.05), higher VE/VCO2 slope tertiles (p <0.05), and values of PetCO2 below median (p < 0.05).

CONCLUSIONS

CPX provides prognostic independent information for risk of SVA in subjects with CHF.

Serum β-carotene and the risk of sudden cardiac death in men: a population-based follow-up study

OBJECTIVES

To examine whether serum concentrations of carotenoids are related to the risk of sudden cardiac death (SCD) in middle-aged men.

METHODS

The study population consisted of 1031 Finnish men aged 46-65 years of the Kuopio Ischemic Heart Disease Risk Factor (KIHD) cohort. Serum concentrations of carotenoids were measured by high-performance liquid chromatography. The hazard ratios (HR) of serum β-carotene, lycopene and α-carotene were estimated by using the Cox proportional hazard model after adjusting for age and other potential confounding factors.

RESULTS

During a median follow-up of 15.9 years a total of 59 incidents of SCD occurred. After controlling for age, systolic blood pressure, waist circumference, smoking, alcohol consumption, years of education, serum LDL cholesterol, serum hs-CRP, diabetes, prevalent coronary heart disease (CHD) and congestive heart failure (CHF), men in the lowest tertile of serum concentrations of β-carotene had a 2-fold increased risk of SCD (HR=2.15, 95% CI: 1.02-4.51; p=0.044) as compared to those in the highest tertile. The risk of SCD was borderline significant for lycopene. In addition, low serum β-carotene concentrations increased the risk of cardiovascular disease (CVD) and total mortality. Lycopene and α-carotene were not related to the risk of SCD.

CONCLUSIONS

Our findings suggest that low serum β-carotene concentrations may increase the risk of SCD in middle-aged Finnish men. Furthermore, low serum β-carotene concentrations may be related to the risk of CVD and total mortality.