Impact of Sustained Cardiac Tachyarrhythmias Recorded in Coronary Intensive Care Unit on Short- and Long-Term Mortality and Duration of Hospitalization.

BACKGROUND: Studies conducted in coronary intensive care units (CICUs) have demonstrated that tachyarrhythmias are associated with increased mortality after acute coronary syndromes (ACSs). However, the data for tachyarrhythmias occurred in CICUs due to a variety of cardiovascular disorders are limited. METHODS: We conducted a single-center prospective observational study, which included consecutive CICU patients (January 1, 2014 to May 31, 2018). We recorded the ventricular arrhythmias (VAs), supraventricular tachycardias (SVTs), and days of CICU hospitalization. The patients were followed up for 6 months after CICU discharge. RESULTS: A total of 943 patients (age: 66.37 ±15.4 years; 673 males [71.4%]) were included. Patients with tachyarrhythmias had higher in-CICU mortality (8.0% vs 4.1%, P = .029, odds ratio [OR]: 2.04, 95% confidence interval [CI]: 1.08-3.86) and higher 6-month all-cause mortality (12.8% vs 6.1%, P = .002, OR: 2.27, 95% CI: 1.35-3.83) than those who did not develop tachyarrhythmias. Ventricular arrhythmias was significantly associated with higher all-cause mortality than no tachyarrhythmia (15.4% vs 6.1%; P = .001) or SVTs (15.4% vs 7.0%; P = .001). The mean duration of hospitalization for the patients with tachyarrhythmias was 3.89 ± 4.90 days, while for the patients without was 2.79 ± 3.31 days (P < .001). Patients without ACS had higher short- and long-term mortality compared to patients with ACS (9.2% vs 2.9%, P < .001 and 12.9% vs 4.9%, P < .001). CONCLUSIONS: Tachyarrhythmias were associated with prolonged CICU hospitalization, while non-ACS cardiovascular disorders and the occurrence of VAs were associated with increased short- and long-term mortality.

Cardiac resynchronization therapy (CRT) device replacement considerations: upgrade or downgrade? A complex decision in the current clinical setting.

There are limited data about the management of patients presenting for elective generator replacements in the setting of previously implanted cardiac resynchronization therapy (CRT) devices that are nearing end-of-life. The individual patient's clinical status and concomitant morbidities may evolve so that considerations may include not only replacement of the pulse generator, but also potentially changing the type of device [e.g. downgrading CRT-defibrillator (CRT-D) to CRT-pacemaker (CRT-P) or ICD or upgrading of CRT-P to CRT-D]. Moreover, the clinical evidence for CRT-D/CRT-P implantation may change over time, with ongoing research and availability of new trial data. In this review we discuss the ethical, clinical and financial implications related to CRT generator replacements and the need for additional clinical trials to better understand which patients should undergo CRT device downgrading or upgrading at the time of battery depletion.

Alterations in the expression of genes related to contractile function and hypertrophy of the left ventricle in chronically paced patients from the right ventricular apex.

AIM: Long-term right ventricular apical (RVA) pacing may lead to left ventricular (LV) remodelling and heart failure. This study assessed changes in the expression of genes regulating LV contractile function and hypertrophy, after permanent RVA pacing and investigated whether such changes proceed or even predict LV remodelling. METHODS AND RESULTS: We enrolled 52 consecutive patients (age 79.1 ± 7.7 years, 34 males) who underwent pacemaker implantation for bradycardic indications: Group A, 24 individuals with atrioventricular conduction disturbances and group B, 28 patients with sinus node disease. In group A, peripheral blood mRNA levels of gene sarcoplasmic reticulum calcium ATPase decreased at 3, 6, and 12 months' follow-up, while α-myosin heavy chain (MHC) decreased and ß-MHC increased until 6 months follow-up. In this group, 25% of patients demonstrated significant LV remodelling. At 4 years, LV end-systolic diameter increased from 29.67 ± 3.39 mm at baseline to 35.38 ± 4.22 mm, LV end-diastolic diameter increased from 50 ± 4.95 to 56.71 ± 5.52 mm, and ejection fraction declined from 63.04 ± 10.22 to 52.83 ± 10.81%. Early alterations in gene expression were associated with a deterioration in LV function and geometry that became apparent months later. In group B, echocardiographic indexes and mRNA levels of the evaluated genes demonstrated no statistically significant changes. CONCLUSIONS: Permanent RVA pacing in patients with preserved ejection fraction is associated with alterations in the expression of genes regulating LV contractile function and hypertrophy, measured in the peripheral blood. These alterations are traceable at an early stage, before echocardiographic changes are apparent and are associated with LV remodelling that becomes evident in the long term.

Arrhythmia-induced cardiomyopathies: the riddle of the chicken and the egg still unanswered?

The hypothesis testing of inappropriate fast, irregular, or asynchronous myocardial contraction provoking cardiomyopathy has been the primary focus of numerous research efforts, especially during the last few decades. Rapid ventricular rates resulting from supraventricular arrhythmias and atrial fibrillation (AF), irregularity of heart rhythm-basic element of AF-and asynchrony, as a consequence of right ventricular pacing, bundle branch block, or frequent premature ventricular complexes, have been established as primary causes of arrhythmia-induced cardiomyopathy. The main pathophysiological pathways involved have been clarified, including neurohumoral activation, energy stores depletion, and abnormalities in stress and strain. Unfortunately, from a clinical point of view, patients usually seek medical advice only when symptoms develop, while the causative arrhythmia may be present for months or years, resulting in myocardial remodelling, diastolic, and systolic dysfunction. In some cases, making a definite diagnosis may become a strenuous exercise for the treating physician, as the arrhythmia may not be present and, additionally, therapy must be applied for the diagnosis to be confirmed retrospectively. The diagnostic process is also hardened due to the fact that strict diagnosing criteria are still a matter of discrepancy. Therapy options include pharmaceutical agents trials, catheter-based therapies and, in the context of chronic ventricular pacing, resynchronization. For the majority of patients, partial or complete recovery is expected, although they have to be followed up thoroughly due to the risk of recurrence. Large, randomized controlled trials are more than necessary to optimize patients' stratification and therapeutic strategy choices.

Mechanisms, risk factors, and management of acquired long QT syndrome: a comprehensive review.

Long QT syndrome is characterized by prolongation of the corrected QT (QTc) interval on the surface electrocardiogram and is associated with precipitation of torsade de pointes (TdP), a polymorphic ventricular tachycardia that may cause sudden death. Acquired long QT syndrome describes pathologic excessive prolongation of the QT interval, upon exposure to an environmental stressor, with reversion back to normal following removal of the stressor. The most common environmental stressor in acquired long QT syndrome is drug therapy. Acquired long QT syndrome is an important issue for clinicians and a significant public health problem concerning the large number of drugs with this adverse effect with a potentially fatal outcome, the large number of patients exposed to these drugs, and our inability to predict the risk for a given individual. In this paper, we focus on mechanisms underlying QT prolongation, risk factors for torsades de pointes and describe the short- and long-term treatment of acquired long QT syndrome.

Novel pacing algorithms: do they represent a beneficial proposition for patients, physicians, and the health care system?

Modern pacemakers are enriched with several embedded algorithms, aiming at achieving a more "physiological" pacing, at reducing pacing-related costs and at maximizing the physician's and the patient's convenience. Though some of these algorithms offer proven benefits, the efficacy of others is still under serious dispute. Herein are presented some of the most important algorithms integrated in modern pacemakers, together with an overview of the currently available literature concerning their efficacy and safety, as well as their impact on the economics of health care systems.

Biventricular pacing in paced patients with normal hearts.

Right ventricular apical (RVA) stimulation, although beneficial in the treatment of symptomatic bradycardia, has proven detrimental in a substantial percentage of pacemaker recipients, leading to iatrogenic deterioration of left ventricular structure and function. Alternative right ventricular pacing sites appeared advantageous but their superiority has not been proven. Biventricular stimulation is effective in reducing ventricular dyssynchrony in subgroups of heart failure patients, improving their functional capacity, morbidity, and mortality. Therefore, it seems logical that this pacing strategy, by eliminating ventricular dyssynchrony, could play an important role in preventing the deleterious effects of chronic RVA stimulation in patients with normal hearts who undergo cardiac pacing for bradycardia indications. Preliminary investigations have yielded encouraging results, but further studies with harder endpoints such as quality of life, morbidity, and mortality are necessary to clarify the potentially advantageous effect of biventricular stimulation in paced patients with normal hearts.

Long-term rhythm monitoring with an implantable loop recorder in patients after the first clinical atrial fibrillation episode. Towards an individualized management.

Although atrial fibrillation (AF) is an arrhythmia with a variable clinical profile (symptomatic and asymptomatic episodes), the first symptomatic episode leads to its initial diagnosis in most cases. Nowadays, continuous and remote long-term cardiac rhythm monitoring is feasible by the use of implantable loop recorders. The data concerning the AF recurrences and progression after the first electrocardiographic-documented clinical AF episode demonstrates that a high percentage of patients may not suffer any other AF recurrence, or may present a low recurrence rate of the arrhythmia in the future. The AF burden may play a key role in the management of the arrhythmia as far as the decision-making for anticoagulation, rate and/or rhythm control therapy is concerned. There is evidence that a higher AF burden is associated with a higher risk of ischemic stroke. Non-vitamin K antagonists (NOACs) anticoagulants are increasingly used in the management of AF, providing a more predictable effect with rapid onset and offset of their action. The use of these agents in combination with devices that provide a continuous remote rhythm monitoring capability has encouraged anticoagulation strategies based on the AF burden. Data from tailored anticoagulation studies in AF are in favor of the long-term rhythm monitoring, ensuring a patient-centered approach with a better evaluation and more individualized management of AF, especially in patients with intermediate thromboembolic risk and high bleeding risk. Further large randomized trials are needed, not only to evaluate such strategies but also to elucidate the long-term cardiac rhythm monitoring in the AF management.

Atrial overdrive pacing for the obstructive sleep apnea-hypopnea syndrome.

BACKGROUND: The role of atrial overdrive pacing (AOP) in sleep apnea remains uncertain. We prospectively evaluated the effect of AOP after 24 hours and after one month in patients with the obstructive sleep apnea-hypopnea syndrome and compared it with the use of nasal continuous positive airway pressure (n-CPAP). METHODS: We studied 16 patients with a moderate or severe case of the obstructive sleep apnea-hypopnea syndrome (baseline mean apnea-hypopnea index, 49) and normal left ventricular systolic function in whom a dual-chamber pacemaker had been implanted. After 48 hours, the patients were randomly assigned to AOP (pacing at 15 bpm above the spontaneous mean nocturnal heart rate) or backup atrial pacing (pacing at a heart rate below 40 bpm); the latter group began n-CPAP therapy one day later. After one month, the two groups switched therapies and were followed for an additional month. Polysomnographic studies were performed at baseline, on the first night after randomization, at crossover, and at the end of the study. RESULTS: During AOP, no significant changes were observed in any of the respiratory variables measured. The change in the apnea-hypopnea index at one month with AOP was +0.2 (95 percent confidence interval, -2.7 to +2.3; P=0.87). In contrast, all variables improved significantly after one month of n-CPAP (change in the apnea-hypopnea index, -46.3; 95 percent confidence interval, -56.2 to -36.5; P<0.001). CONCLUSIONS: Nasal continuous positive airway pressure therapy is highly effective for the treatment of the obstructive sleep apnea-hypopnea syndrome, whereas AOP has no significant effect.

Sleep-disordered breathing in heart failure and the effect of cardiac resynchronization therapy.

Respiratory disturbances during sleep are common in patients with heart failure (HF) and can trigger the occurrence of sleep apnoea or deteriorate pre-existing breathing disorder. This in turn may lead to worsening of the HF itself. Optimal treatment for HF has been found to reduce respiratory disturbances during sleep significantly, whereas cardiac resynchronization therapy (CRT), achieved by biventricular pacing, appears to cause a further reduction in episodes of central type apnoea, although it may also have an effect on episodes of obstructive type. The beneficial effect of CRT is due to the patients' haemodynamic improvement and in the HF amelioration, and not due to some other effect resulting from the electrical stimulation of the heart. However, this therapeutic intervention by itself is insufficient for the effective treatment of respiratory disturbances during sleep and should be considered as an adjunctive treatment in addition to other established therapies.

CRT and exercise capacity in heart failure: the impact of mitral valve regurgitation.

Cardiac resynchronization therapy (CRT) has emerged as an established therapy for patients with end-stage heart failure (HF) and symptoms refractory to optimal medication. Resynchronization of the ventricles leads to reduced functional mitral regurgitation (MR) both acutely and chronically and to a better haemodynamic and energetic profile. In addition, large clinical trials have confirmed its beneficial effect on exercise performance and quality of life. The link between the pathophysiological mechanisms of CRT and its positive effect on clinical status has not been fully elucidated. Therefore, this review will focus on the effect of CRT on the haemodynamic role of functional MR and its impact on exercise performance in patients with chronic HF.

Recurrence rate of atrial fibrillation after the first clinical episode: A prospective evaluation using continuous cardiac rhythm monitoring.

BACKGROUND: Decision making regarding a patient who has experienced a first clinical episode of atrial fibrillation (AF) is challenging, and the AF recurrences should be a significant consideration. Continuous long-term rhythm monitoring via implantable loop recorders (ILRs) has enabled us to evaluate the AF recurrence profile after the first clinical episode and to investigate clinical parameters associated with the course of the arrhythmia. HYPOTHESIS: Continuous rhythm monitoring via ILRs in AF patients after the first clinical episode is of clinical significance and precisely evaluate the AF recurrence profile. METHODS: Thirty consecutive patients with paroxysmal AF received an ILR after their first symptomatic episode. We evaluated the maximum duration of episodes and the recurrence rate of the arrhythmia during a follow-up period of 3 years. RESULTS: Three patients (10%) had no AF recurrence, whereas 4 patients (13.3%) presented only 1 episode. Almost half of the patients (46.7%) had a low recurrence rate (<5 episodes/year), whereas the majority of patients (19/30) suffered from episodes with maximum duration ≤24 hours. Eleven patients (36.7%) presented either no episode or a low recurrence rate with episodes lasting ≤24 hours. The use of statins was greater in patients with a low recurrence rate (P = 0.025). CONCLUSIONS: A significant percentage of patients either suffer no AF recurrence after their first symptomatic episode or show a low recurrence rate. Most patients present episodes of short duration. If these findings are confirmed in larger studies, they could have clinical implications ensuring individualized management of the arrhythmia in the future.

Long-term clinical outcomes in implantable cardioverter defibrillator recipients on the island of Crete.

PURPOSE: The aim of the current study is to disseminate long-term "real-world" data on mortality and device therapies in primary and secondary prevention implantable cardioverter defibrillator (ICD) recipients on the island of Crete. METHODS: We analyzed data for all consecutive patients who received an ICD in our tertiary university hospital from 1993 until December 2013. Follow-up visits were performed every 6 months or more frequently when indicated. Survival status was recorded, and all stored episodes during interrogation were registered and classified as appropriate or inappropriate. RESULTS: In total, 854 patients received an ICD; 623 (73%) for primary and 231 (27%) for secondary prevention. Most of these patients (490) suffered from ischemic cardiomyopathy. During the mean follow-up of 12.4±7.8 years, 218 (25.5%) patients died; 19.7% in the primary prevention group (p=0.008) and 41.1% in the secondary prevention group. Overall, 248 patients (29%) received appropriate therapy; however, the percentage was significantly higher in the secondary prevention group (44.2%) than in primary prevention group (23.4%). The cumulative incidence of inappropriate therapies during the mean follow-up period was 11.6%. Lead-related complications were noted in 49 patients (5.7%), while only 13 patients (1.5%) suffered device-related infections. CONCLUSIONS: The long-term data related to clinical outcomes in ICD recipients in our center are in accordance with those of other international centers and confirm the high efficacy and safety of these devices in preventing sudden cardiac death.

Left ventricular mechanics during right ventricular apical or left ventricular-based pacing in patients with chronic atrial fibrillation after atrioventricular junction ablation.

OBJECTIVES: The aim of the study was to evaluate whether left ventricular (LV) mechanics are better under LV-based pacing than under right ventricular (RV) apical pacing in patients with permanent atrial fibrillation (AF) after atrioventricular junction (AVJ) ablation. BACKGROUND: "Ablate and pace" is an acceptable therapy for drug-refractory AF. However, the RV apical stimulation commonly used seems to interfere with the beneficial hemodynamic effect of regularization of heart rhythm. METHODS: The study included 12 patients (5 men, mean age 62 +/- 8.3 years), 6 with impaired and 6 with normal LV systolic function. All of them had a biventricular pacemaker system implanted and underwent atrioventricular node ablation for drug-refractory chronic AF. Using a conductance catheter, we analyzed LV pressure-volume loops during routine coronary angiography in order to evaluate short-term changes in LV mechanics during RV apical and LV-based (LV free wall or biventricular) pacing. RESULTS: Compared with RV pacing, LV-based pacing significantly improved the indexes of LV systolic function (i.e., end-systolic pressure and volume, cardiac index, stroke work, preload recruitable stroke work, maximal rate of rise of LV pressure [dP/dt(max)], LV ejection fraction, and end-systolic elastance). The LV diastolic filling indexes, end-diastolic pressure and volume, were better during LV-based pacing, whereas LV diastolic function indexes, -dP/dt(max), passive diastolic chamber stiffness, and time constant of LV isovolumic relaxation showed no clear change. CONCLUSIONS: In the short term, LV-based pacing is superior to RV apical pacing in terms of contractile function and LV filling after AVJ ablation for drug-refractory AF.

Left ventricular mechanics and myocardial blood flow following restoration of normal activation sequence in paced patients with long-term right ventricular apical stimulation.

STUDY OBJECTIVES: Asynchronous ventricular activation, as induced by ventricular pacing, is known to affect left ventricular (LV) systolic and diastolic function and myocardial blood flow. However, it is not clear whether the long-term disturbances it causes are reversible after the restoration of the normal ventricular activation sequence. DESIGN: In this study, we used the conductance catheter method and a Doppler guidewire to assess the changes in LV mechanics, and correspondingly in myocardial blood flow, after the restoration of the normal ventricular activation sequence in patients with long-term right ventricular apical pacing. PATIENTS: Sixteen patients (mean [+/- SD] age, 61 +/- 11 years; 9 men) with right ventricular apical stimulation and complete ventricular pacing capture for a very long period were studied. In eight patients, we analyzed pressure-volume loops before and immediately after the restoration of the normal ventricular activation sequence, and in the remaining eight patients the myocardial blood flow and flow reserve were analyzed. MEASUREMENTS AND RESULTS: End-systolic elastance (Ees) [5.503 +/- 0.6 vs 4.287 +/- 0.28 mm Hg/mL, respectively; p = 0.003] and its ratio to effective arterial elastance (1.63 +/- 0.51 vs 2.00 +/- 0.64, respectively; p = 0.009), which are indexes of systolic function and ventriculoarterial coupling, respectively, improved significantly after restoration of the normal ventricular activation sequence. Indexes of diastolic function and the predicted myocardial oxygen consumption (MO(2)) showed no clear change. Coronary flow in the dominant coronary artery increased significantly (46.55 +/- 14.12 vs 71.55 +/- 27.53 mL/min, respectively; p = 0.002), while the coronary flow reserve in the same artery decreased (3.5 +/- 1.0 vs 2.6 +/- 0.5, respectively; p = 0.008). CONCLUSIONS: The restoration of a normal activation sequence after long-term ventricular asynchrony enhances acutely contractile function without affecting MO(2). These changes in LV function do not appear to have causal relationships with myocardial blood flow changes.