Basic science of cardiac contractility modulation therapy: Molecular and electrophysiological mechanisms

In heart failure with reduced ejection fraction and heart failure with preserved ejection fraction, profound cellular and molecular changes have recently been documented in the failing myocardium. These changes include altered calcium handling and metabolic efficiency of the cardiac myocyte, reactivation of the fetal gene program, changes in the electrophysiological properties of the heart, and accumulation of collagen (fibrosis) at the interstitial level. Cardiac contractility modulation therapy is an innovative device-based therapy currently approved for heart failure with reduced ejection fraction in patients with narrow QRS complex and under investigation for the treatment of heart failure with preserved ejection fraction. This therapy is based on the delivery of high-voltage biphasic electrical signals to the septal wall of the right ventricle during the absolute refractory period of the myocardium. At the cellular level, in patients with heart failure with reduced ejection fraction, cardiac contractility modulation therapy has been shown to restore calcium handling and improve the metabolic status of cardiac myocytes, reverse the heart failure-associated fetal gene program, and reduce the extent of interstitial fibrosis. This review summarizes the preclinical literature on the use of cardiac contractility modulation therapy in heart failure with reduced and preserved ejection fraction, correlating the molecular and electrophysiological effects with the clinical benefits demonstrated by this therapy.

Measurement of Cardiac-Specific Biomarkers in the Emergency Department: New Insight in Risk Evaluation

The aim of this article review is to analyze some models and clinical issues related to the implementation of accelerated diagnostic protocols based on specific cardiac biomarkers in patients admitted to the emergency department (ED) with symptoms compatible with acute cardiac disorders. Four specific clinical issues will be discussed in detail: (a) pathophysiological and clinical interpretations of circulating hs-cTnI and hs-cTnT levels; (b) the clinical relevance and estimation of the biological variation of biomarkers in patients admitted to the ED with acute and severe diseases; (c) the role and advantages of the point-of-care testing (POCT) methods for cardiac-specific biomarkers in pre-hospital and hospital clinical practice; and (d) the clinical role of specific cardiac biomarkers in patients with acute heart failure (AHF). In order to balance the risk between a hasty discharge versus the potential harms caused by a cardiac assessment in patients admitted to the ED with suspected acute cardiovascular disease, the measurement of specific cardiac biomarkers is essential for the early identification of the presence of myocardial dysfunction and/or injury and to significantly reduce the length and costs of hospitalization. Moreover, specific cardiac biomarkers (especially hs-cTnI and hs-cTnT) are useful predictors of mortality and major adverse cardiovascular events (MACE) in patients admitted to the ED with suspected acute cardiovascular disease. To guide the implementation of the most rapid algorithms for the diagnosis of Non-ST-Elevation Myocardial Infarction (NSTEMI) into routine clinical practice, clinical scientific societies and laboratory medicine societies should promote collaborative studies specifically designed for the evaluation of the analytical performance and, especially, the cost/benefit ratio resulting from the use of these clinical protocols and POCT methods in the ED clinical practice.

The Liver in Heart Failure: From Biomarkers to Clinical Risk

Heart failure (HF) is a clinical syndrome due to heart dysfunction, but in which other organs are also involved, resulting in a complex multisystemic disease, burdened with high mortality and morbidity. This article focuses on the mutual relationship between the heart and liver in HF patients. Any cause of right heart failure can cause hepatic congestion, with important prognostic significance. We have analyzed the pathophysiology underlying this double interaction. Moreover, we have explored several biomarkers and non-invasive tests (i.e., liver stiffness measurement, LSM) potentially able to provide important support in the management of this complex disease. Cardiac biomarkers have been studied extensively in cardiology as a non-invasive diagnostic and monitoring tool for HF. However, their usefulness in assessing liver congestion in HF patients is still being researched. On the other hand, several prognostic scores based on liver biomarkers in patients with HF have been proposed in recent years, recognizing the important burden that liver involvement has in HF. We also discuss the usefulness of a liver stiffness measurement (LSM), which has been recently proposed as a reliable and non-invasive method for assessing liver congestion in HF patients, with therapeutic and prognostic intentions. Lastly, the relationship between LSM and biomarkers of liver congestion is not clearly defined; more research is necessary to establish the clinical value of biomarkers in assessing liver congestion in HF patients and their relationship with LSM.

1094 MULTIVESSEL CORONARY ARTERY SPASM TRIGGERED BY GANGLIONATED PLEXI STIMULATION DURING ATRIAL FIBRILLATION RADIOFREQUENCY CATHETER ABLATYION: A CASE REPORT

Background

Atrial fibrillation is the most common sustained cardiac arrhythmia in adults and it is associated with a high burden of mortality and morbidity worldwide. Atrial fibrillation could be managed with rate-control or rhythm-control strategies. The latter is increasingly used to improve symptoms and prognosis in selected patients, especially after the development of catheter ablation. Although this technique is generally considered safe, it is not free from rare but life-threatening procedure-related adverse events. Among these, coronary artery spasm is an uncommon but potentially fatal complication that requires immediate diagnosis and treatment.

Case summary

We report a case of severe multivessel coronary artery spasm triggered by ganglionated plexi stimulation during pulmonary vein isolation with radiofrequency catheter ablation in a patient with persistent atrial fibrillation, promptly resolved after intracoronary nitrate administration.

Discussion

Although rare, coronary artery spasm is a serious complication of atrial fibrillation catheter ablation. Immediate invasive coronary angiography is key for both diagnosis confirmation and treatment of such dangerous condition. As the number of invasive procedures increases, it is important that both interventional and general cardiologists are aware of possible procedure-related adverse events.

427 MUTUAL INTERDEPENDENCE OF BNP, PLASMA VOLUME, RENAL FUNCTION AND LVEF IN HEALTHY SUBJECTS

Background

Natriuretic peptides play an important role in cardiovascular control, stimulating diuresis and vasodilatation and suppressing the renin-angiotensin-aldosterone system. They are also pivotal markers in diagnosis, prognosis and therapy of heart failure (HF), specially BNP and its precursor pro-hormone Nt-proBNP. .Many factors can affect BNP levels in HF patients, potentially reducing its diagnostic accuracy. The main important ones include left ventricular ejection fraction (LVEF), glomerular filtration rate (GFR) and plasma volume (PV). Though the mutual relationship between BNP levels and these drivers is well studied in HF patients, paradoxically little is known about this relationship in physiological conditions in healthy subjects. We tried to elucidate mutual interdependence of BNP, PV, renal function and LVEF in healthy subjects.

Methods

A total of 200 healthy adult males underwent clinical assessment, measurement of serum levels of BNP, creatinine, uricemia, hemochrome and echocardiography for LVEF assessment. GFR was calculated according to EPI-CKD formula. PV was estimated with both the Hakim formula and the Kaplan formula. The ideal PV (iPV) i.e. the normal PV was calculated using body weight and sex: iPV (in ml) = c × body weight (in kg), where c = 39 in males and 40 in females.

Results

Mean levels of BP, LVEF, BNP, serum creatinine, GFR, uricemia and PV were all within the normal range. PV1 and PV2 were significantly different from each other and both differed from iPV (Friedman ANOVA; | = 28.4; df = 2; P <0.01 for all the comparisons). Nevertheless, the three estimates of PV were all significantly and strictly correlated to each other (Spearman correlation coefficient, Rho >0.82 and P<0.001 for all the correlations). BNP levels were positively correlated with age and inversely with both uricemia and iPV. The latter ones were positively correlated to each other. GFR was inversely correlated with both age and uricemia (but not with PV nor with BNP levels). No correlation was found between LVEF and BNP levels or PV.

Conclusions

In homeostatic conditions, BNP and PV are inversely correlated in healthy adult males (contrary to the positive correlation existing in HF patients due to the predominant effects of angiotensin II and aldosterone), whereas opposite correlations between uricemia and both PV (positive) and GFR (negative) exist. The positive correlation between uricemia and PV could be explained by the strict dependence of tubular reabsorption of uric acid on serum levels of sodium, which is in turn strictly related to the extracellular fluid volume. The negative correlation between uricemia and GFR can be explained by the mutual influence of these two factors, since hyperuricemia seems to be both a cause and a consequence of chronic kidney disease (CKD).