Significance and control of cardiac arrhythmias in patients with congestive cardiac failure

Stellate Ganglia and Cardiac Sympathetic Overactivation in Heart Failure

Heart failure (HF) is a major public health problem worldwide, especially coronary heart disease (myocardial infarction)-induced HF with reduced ejection fraction (HFrEF), which accounts for over 50% of all HF cases. An estimated 6 million American adults have HF. As a major feature of HF, cardiac sympathetic overactivation triggers arrhythmias and sudden cardiac death, which accounts for nearly 50–60% of mortality in HF patients. Regulation of cardiac sympathetic activation is highly integrated by the regulatory circuitry at multiple levels, including afferent, central, and efferent components of the sympathetic nervous system. Much evidence, from other investigators and us, has confirmed the afferent and central neural mechanisms causing sympathoexcitation in HF. The stellate ganglion is a peripheral sympathetic ganglion formed by the fusion of the 7th cervical and 1st thoracic sympathetic ganglion. As the efferent component of the sympathetic nervous system, cardiac postganglionic sympathetic neurons located in stellate ganglia provide local neural coordination independent of higher brain centers. Structural and functional impairments of cardiac postganglionic sympathetic neurons can be involved in cardiac sympathetic overactivation in HF because normally, many effects of the cardiac sympathetic nervous system on cardiac function are mediated via neurotransmitters (e.g., norepinephrine) released from cardiac postganglionic sympathetic neurons innervating the heart. This review provides an overview of cardiac sympathetic remodeling in stellate ganglia and potential mechanisms and the role of cardiac sympathetic remodeling in cardiac sympathetic overactivation and arrhythmias in HF. Targeting cardiac sympathetic remodeling in stellate ganglia could be a therapeutic strategy against malignant cardiac arrhythmias in HF.

Heart failure and atrial fibrillation: new concepts in pathophysiology, management, and future directions

A bidirectional pathophysiological link connects heart failure and atrial fibrillation, creating a frequent and challenging comorbidity, which includes neurohormonal hyperactivation, fibrosis development, and electrophysiologic remodeling, while they share mutual risk factors. Management for these devastating comorbidities includes most of the established treatment measures for heart failure as well as rhythm or rate control and anticoagulation mostly for atrial fibrillation, which can be achieved with either pharmaceutical or non-pharmaceutical approaches. The current manuscript aims to review the existing literature regarding the underlying pathophysiology, to present the novel trends of treatment, and to predict the future perspective of these two linked diseases with the numerous unanswered questions.

Substrates and potential therapeutics of ventricular arrhythmias in heart failure

Heart failure (HF) is a clinical syndrome characterized by ventricular contractile dysfunction. About 50% of death in patients with HF are due to fetal ventricular arrhythmias including ventricular tachycardia and ventricular fibrillation. Understanding ventricular arrhythmic substrates and discovering effective antiarrhythmic interventions are extremely important for improving the prognosis of patients with HF and reducing its mortality. In this review, we discussed ventricular arrhythmic substrates and current clinical therapeutics for ventricular arrhythmias in HF. Base on the fact that classic antiarrhythmic drugs have the limited efficacy, side effects, and proarrhythmic potentials, we also updated some therapeutic strategies for the development of potential new antiarrhythmic interventions for patients with HF.

Association between vitamin D deficiency and heart failure risk in the elderly

AIMS

The aim of this study was to evaluate the association between vitamin D deficiency and risk of heart failure in elderly patients of cardiology outpatient clinics.

METHODS AND RESULTS

A cross-sectional study with an analytical approach was employed. Clinical data were collected from the elderly from August 2015 to February 2016. The dependent variable was the risk of heart failure; the independent variable was vitamin D deficiency; and intervening factors were age, gender, education, ethnicity, hypertension, diabetes mellitus, hypothyroidism, renal failure, dementia, stroke, dyslipidaemia, depression, smoking, alcoholism, obesity, andropause, and cardiac arrhythmia. To analyse the association between vitamin D deficiency and risk of heart failure, we used the bivariate logistic analysis, followed by analysis through the multivariate logistic regression model. Of the 137 elderly, the study found the following: women (75.9%); overweight (48.2%); obese (30.6%); increase in the index waist/hip (88.3%); dyslipidaemia (94.2%) and hypertension (91.2%); coronary artery disease (35.0%); and 27.7% with cardiac arrhythmia or left ventricular hypertrophy. Sixty-five per cent of the elderly were deficient in vitamin D. The risk of heart failure was significantly associated with vitamin D deficiency [odds ratio (OR): 12.19; 95% confidence interval (CI) = 4.23-35.16; P = 0.000], male gender (OR: 15.32; 95% CI = 3.39-69.20, P = 0.000), obesity (OR: 4.17; 95% CI = 1.36-12.81; P = 0.012), and cardiac arrhythmia (OR: 3.69; 95% CI = 1.23-11.11; P = 0.020).

CONCLUSIONS

There was a high prevalence of vitamin D deficiency in the elderly, and the evidence shows a strong association between vitamin D deficiency and increased risk of heart failure in this population.

Reduced N-Type Ca2+ Channels in Atrioventricular Ganglion Neurons Are Involved in Ventricular Arrhythmogenesis

Background

Attenuated cardiac vagal activity is associated with ventricular arrhythmogenesis and related mortality in patients with chronic heart failure. Our recent study has shown that expression of N‐type Ca²⁺ channel α‐subunits (Ca_v2.2‐α) and N‐type Ca²⁺ currents are reduced in intracardiac ganglion neurons from rats with chronic heart failure. Rat intracardiac ganglia are divided into the atrioventricular ganglion (AVG) and sinoatrial ganglion. Ventricular myocardium receives projection of neuronal terminals only from the AVG. In this study we tested whether a decrease in N‐type Ca²⁺ channels in AVG neurons contributes to ventricular arrhythmogenesis.

Methods and Results

Lentiviral Ca_v2.2‐α shRNA (2 μL, 2×10⁷ pfu/mL) or scrambled shRNA was in vivo transfected into rat AVG neurons. Nontransfected sham rats served as controls. Using real‐time single‐cell polymerase chain reaction and reverse‐phase protein array, we found that in vivo transfection of Ca_v2.2‐α shRNA decreased expression of Ca_v2.2‐α mRNA and protein in rat AVG neurons. Whole‐cell patch‐clamp data showed that Ca_v2.2‐α shRNA reduced N‐type Ca²⁺ currents and cell excitability in AVG neurons. The data from telemetry electrocardiographic recording demonstrated that 83% (5 out of 6) of conscious rats with Ca_v2.2‐α shRNA transfection had premature ventricular contractions (P<0.05 versus 0% of nontransfected sham rats or scrambled shRNA‐transfected rats). Additionally, an index of susceptibility to ventricular arrhythmias, inducibility of ventricular arrhythmias evoked by programmed electrical stimulation, was higher in rats with Ca_v2.2‐α shRNA transfection compared with nontransfected sham rats and scrambled shRNA‐transfected rats.

Conclusions

A decrease in N‐type Ca²⁺ channels in AVG neurons attenuates vagal control of ventricular myocardium, thereby initiating ventricular arrhythmias.

Practical applicability of landiolol, an ultra-short-acting β1-selective blocker, for rapid atrial and ventricular tachyarrhythmias with left ventricular dysfunction

Background

Landiolol effectively controls rapid heart rate in atrial fibrillation or flutter (AF/AFL) patients with left ventricular (LV) dysfunction. However, predicting landiolol Responders and Non-Responders and patients who will experience adverse effects remains a challenge. The aim of this study was to clarify the potential applicability of landiolol for rapid AF/AFL and refractory ventricular tachyarrhythmias (VTs) in patients with heart failure.

Methods

A total of 39 patients with AF/AFL with ventricular response ≥120 bpm and 12 VTs were retrospectively enrolled. Landiolol Responders for rapid AF/AFL were defined as patients whose ventricular response was suppressed to less than 110 bpm or decreased by ≥20% from the initial heart rate after administration of landiolol. Responders for VTs were defined as patients with no recurrent VTs during the 24 h after the initiation of landiolol.

Results

For AF/AFL, 29 patients (74%) were Responders. In nine patients (31%), AF was spontaneously terminated after starting landiolol. Eight Non-Responders (80%) needed to have AF terminated by cardioversion. Left ventricular ejection fraction (LVEF) at baseline was significantly associated with landiolol efficacy. For VTs, seven patients (58%) were Responders, and smaller LV diastolic and systolic diameters were associated with landiolol efficacy. Hypotension after landiolol treatment occurred in 5 of 51 patients, and lower LV systolic function was associated with the development of adverse events.

Conclusions

Landiolol is effective in patients with heart failure not only due to rapid AF/AFL but also due to VTs. However, preserved LVEF is important for efficacy and safety in landiolol treatment.

Cryoablation during left ventricular assist device implantation reduces postoperative ventricular tachyarrhythmias

BACKGROUND

The number of patients undergoing implantation of a HeartMate II left ventricular assist device (LVAD; Thoratec Corporation, Pleasanton, Calif) is rising. Ventricular tachyarrhythmia (VA) after placement of the device is common, especially among patients with preoperative VA. We sought to determine whether intraoperative cryoablation in select patients reduces the incidence of postoperative VA.

METHODS

From January 2009 through September 2010, 50 consecutive patients undergoing implantation of the HeartMate II LVAD were examined. Fourteen of these patients had recurrent preoperative VA. Of those patients with recurrent VA, half underwent intraoperative cryoablation (Cryo: n = 7) and half did not (NoCryo: n = 7). Intraoperatively, patients underwent localized epicardial and endocardial cryoablation via LVAD ventriculotomy. Cryothermal lesions were created to connect scar to fixed anatomic borders in the region of clinical VA. Demographics, risk factors, intraoperative features, and outcomes were analyzed to investigate the feasibility of cryoablation.

RESULTS

Thirty-day mortality remained low (n = 1, 2%) among all LVAD recipients. There were no differences in risk factors between groups except that preoperative inotropes were less prevalent in Cryo patients (P = .09). Compared with NoCryo, the Cryo group had significantly decreased postoperative resource use and complications (P < .05). Recurrent postoperative VA did not develop in any of the Cryo patients (P = .02).

CONCLUSIONS

Postoperative VA can be minimized by preoperative risk assessment and intraoperative treatment. Localized cryoablation in select patients offers promising early feasibility when performed during HeartMate II LVAD implantation. Further prospective analysis is required to investigate this novel approach.

Ventricular arrhythmias during left ventricular assist device support

Left ventricular assist devices (LVADs) have been used effectively as a "bridge" to cardiac transplantation and as destination therapy in patients with advanced heart failure. Ventricular arrhythmias (VAs) have been reported to occur in LVAD-supported patients, although their incidence, risk factors, and clinical significance have not been characterized. In this study, 111 patients who received LVAD support as a bridge to cardiac transplantation at the University of Pittsburgh Medical Center from January 1987 to June 2001 were evaluated. Clinically significant VA was defined as ventricular fibrillation, sustained ventricular tachycardia, or nonsustained ventricular tachycardia with symptoms requiring antiarrhythmic therapy. Patients were grouped on the basis of the presence or absence of VAs. VAs occurred in 24 patients (22%) during device support. Ischemic heart disease was the cause of heart failure in 71% of patients (17 of 24) in the VA group and 45% of patients (39 of 87) in the group without VAs (p <0.05). The mortality rate was significantly higher (p <0.001) during LVAD support in the group with VAs (33%) compared with the group without VAs (18%). In the group with VAs, the early (<or=1 week) occurrence of VAs was associated with a significantly higher (p <0.001) mortality rate (54%) compared with late (>1 week) occurrence (9%). In conclusion, although clinically significant VAs occur in patients with heart failure receiving LVAD support, the overall incidence is low. VAs are more frequent in patients with ischemic heart failure, and their occurrence is associated with greater mortality. The occurrence of VAs early after LVAD implantation, in particular, predicts a higher mortality rate.

Neurohormonal intervention to reduce sudden cardiac death in heart failure: what is the optimal pharmacologic strategy?

Sudden cardiac death (SCD) accounts for up to 50% of deaths in patients with heart failure (HF), depending on severity of symptomatic impairment and left ventricular dysfunction. Neurohormonal therapy directed at the renin-angiotensin-aldosterone system may reduce the propensity to SCD through improved hemodynamic responsiveness, reduced sympathetic tone in the myocardium and inhibition of cardiac remodelling. Angiotensin converting enzyme (ACE) inhibitors reduce overall mortality in chronic HF, the greatest benefit appearing to arises from reduction of HF progression rather than SCD. In HF patients who experience myocardial infarction (MI) reduced incidence in SCD may make a more marked contribution to the mortality benefits of ACE inhibition. Addition of beta-blocker therapy to ACE inhibition has consistently resulted in a reduction in SCD in patients with either mild-to-moderate or severe HF, and in the presence or absence of MI; the reduction in SCD is of the order of one-third versus placebo. Aldosterone blockade reduces the risk of SCD in advanced chronic heart failure (when added to ACE inhibitor) and in HF associated with acute MI (when given in addition to both ACE inhibitor and beta blocker). The evidence base suggests that for maximal SCD risk reduction in HF, beta-blocker therapy is advisable in combination with standard ACE inhibitor therapy, with addition of aldosterone blockade to this regimen for particular groups of heart failure patients.

Effects of Repeated Sauna Treatment on Ventricular Arrhythmias in Patients With Chronic Heart Failure

BACKGROUND

The aim of the present study was to determine whether repeated 60 degrees C sauna treatment improves cardiac arrhythmias in chronic heart failure (CHF) patients, because ventricular arrhythmias are an important therapeutic target in CHF.

METHODS AND RESULTS

Thirty patients (59+/-3 years) with New York Heart Association functional class II or III CHF and at least 200 premature ventricular contractions (PVCs)/24 h assessed by 24-h Holter recordings were studied. They were randomized into sauna-treated (n=20) or non-treated (n=10) groups. The sauna-treated group underwent a 2-week program of a daily 60 degrees C far infrared-ray dry sauna for 15 min, followed by 30 min bed rest with blankets, for 5 days per week. Patients in the non-treated group had bed rest in a temperature-controlled room (24 degrees C) for 45 min. The total numbers of PVCs/24 h in the sauna-treated group decreased compared with the non-treated group [848+/-415 vs 3,097+/-1,033/24 h, p<0.01]. Heart rate variability (SDNN, standard deviation of normal-to-normal beat interval) increased [142+/-10 (n=16) vs 112+/-11 ms (n=8), p<0.05] and plasma brain natriuretic peptide concentrations decreased [229+/-54 vs 419+/-110 pg/ml, p<0.05] in the sauna-treated group compared with the non-treated group.

CONCLUSION

Repeated sauna treatment improves ventricular arrhythmias in patients with CHF.

Oral class III antiarrhythmics: what is new?

PURPOSE OF REVIEW

This review describes the latest developments in the clinical usage of class III antiarrhythmics. It also discusses some new studies providing insight into the mechanism of action of these drugs.

RECENT FINDINGS

New data suggest that amiodarone is one of the most effective drugs for management of ventricular as well as supraventricular tachyarrhythmias. As over the years we have learned to deal with the toxic side effects of this drug, the risk of bradyarrhythmias requiring placement of a pacemaker is becoming more significant. Sotalol was approved for treatment of atrial fibrillation and atrial flutter (AF). It was also found to be effective in management of postoperative AF. Dofetilide has been approved for the conversion and maintenance of sinus rhythm in AF; its role in ventricular arrhythmias remains unclear. Data are emerging regarding clinical efficacy of azimilide and dronedarone.

SUMMARY

Management of arrhythmias in patients with structural heart disease remains a challenge. Class III antiarrhythmics are the mainstay of treatment in this group of patients.