Impact of dexmedetomidine on electrophysiological properties and arrhythmia inducibility in adult patients referred for reentrant supraventricular tachycardia ablation.

BACKGROUND: Drugs used for sedation/analgesia may affect the basic cardiac electrophysiologic properties or even supraventricular tachycardia (SVT) inducibility. Dexmedetomidine (DEX) is a selective alpha-2 adrenergic agonist with sedative and analgesic properties. A comprehensive evaluation on use of DEX for reentrant SVT ablation in adults is lacking. The present study aims to systematically assess the impact of DEX on cardiac electrophysiology and SVT inducibility. METHODS: Hemodynamic, electrocardiographic, and electrophysiological parameters and SVT inducibility were assessed before and after DEX infusion in patients scheduled for ablation of reentrant SVT. RESULTS: The population of this prospective observational study included 55 patients (mean age of 58.7 ± 14 years, 29 males [52.7%]). A decrease in systolic and diastolic blood pressure and in heart rate was observed after DEX infusion (p = 0.001 for all). DEX increased corrected sinus node refractory time, atrial effective refractory period, AH interval, AV Wenckebach cycle length, and AV node effective refractory period without affecting the His-Purkinje conduction or ventricular myocardium refractoriness. No AV blocks or sinus arrests occurred during DEX infusion. Globally, there was no difference in SVT inducibility in basal condition or after DEX infusion (46/55 [83.6%] vs. 43/55 [78.1%] patients; p = 0.55), without a difference in isoprenaline use (p = 1.0). In 4 (7.3%) cases, the SVT was inducible only after DEX infusion. In 34.5% of cases, DEX infusion unmasked the presence of an obstructive sleeping respiratory pattern, represented mainly by snoring. CONCLUSIONS: DEX depresses sinus node function and prolongs atrioventricular refractoriness without significantly affecting the rate of SVT inducibility in patients scheduled for reentrant SVT ablation.

Incidence of ventricular arrhythmias after biventricular defibrillator replacement: impact on safety of downgrading from CRT-D to CRT-P.

BACKGROUND: Cardiac resynchronization therapy (CRT) reduces mortality and hospitalizations. It is debated whether CRT alone (CRT-P) or CRT plus defibrillator (CRT-D) is preferable, and still guidelines are not exhaustive. The aim of the study was to investigate whether to implant CRT-P or CRT-D in CRT-D patients who did not experience malignant arrhythmias at the moment of replacement. METHODS: Out of 451 heart failure patients undergoing CRT-D according to guidelines, 103 (67±10 years, 80% men) underwent device replacement with CRT-D. Every 6 months patients underwent to clinical evaluation and device interrogation and episodes of ventricular arrhythmias (VA) stored. At baseline and before replacement echocardiogram was performed. Patients were defined responders if left ventricular (LV) end-systolic volume decreased ≥15% and super-responders if LV ejection fraction increased ≥40% or ≥50%. RESULTS: Mean follow-up was 75±24 months after implantation and 26±10 months after replacement. First VAs incidence per year did not decrease over time (P=0.619). Before replacement, 27 patients (26.2%, 15 responders/12 non-responders) experienced VA. After replacement, 8 patients (7.7%, 4 responders/4 non-responders) experienced VA for the first time. Super-responder condition was not associated with lower VA incidence before (0.499) and after (P=0.339) replacement. At multivariate analysis, age was the only independent predictor of electrical appropriate therapy after substitution (ORper year=1.17; 95% CI: 1.03-1.34; P=0.003). CONCLUSIONS: Freedom from VA before device replacement does not correlate with freedom from VA after replacement, so downgrade from CRT-D to CRT-P is not feasible at replacement, in particular in the elderlies, independently of responder and super-responder condition.

Ventricular Preexcitation: An Anomalous Wave Interfering with the Ordered Ventricular Activation.

Ventricular preexcitation is a depolarization of the ventricles that occurs before the conventional sequence, and the electrocardiogram is the specific test for diagnosis. A Kent bundle is the paradigm of ventricular preexcitation, and it is associated with short PR, wide QRS and delta wave. This finding is not always very evident, as it can have different degrees of pre-eccitazione; therefore great diagnostic care must be taken in this field. If not properly identified, the pattern of ventricular preexcitation may lead to an incorrect diagnosis. The methodology of precision electrocardiology is able to confront all these aspects.

Surface Electrocardiogram Recording: Baseline 12-lead and Ambulatory Electrocardiogram Monitoring.

The 12-lead standard electrocardiogram (ECG) is a 10 second recording of human myocytes electrical activity. Filters and oversampling are necessary in order to acquire a smooth signal without distortion. ECG recordings may display ongoing arrhythmias, and some leads may be helpful in formulating the diagnosis. Advanced modalities of baseline ECG recording can be used to extract additional information with significant prognostic value. Ambulatory ECG (AECG) recording is a long-term and low-cost external recording obtained with 1 to 12 leads lasting from 24 to 30 days. For patient comfort, longer AECG recordings use fewer leads.

Complex Arrhythmias Due to Reversible Causes.

Abnormalities in cardiac rhythm are caused by disorders of impulse generation, conduction, or a combination of the 2, and may be life-threatening because of a reduction in cardiac output or myocardial oxygenation. Cardiac arrhythmias are commonly classified as tachycardias (supraventricular or ventricular) or bradycardias. Bradycardias are uncommon in the critically ill patient and often are caused by an underlying reversible disorder (eg, hyperkalemia, drug toxicity). Supraventricular and ventricular tachycardias are more often encountered in the critically ill patient and often have underlying treatable disorders that precipitate their development (eg, hypokalemia, hypomagnesemia, antiarrhythmic proarrhythmia, myocardial ischemia).

Meta-analysis of Clinical Outcomes of Electrical Cardioversion and Catheter Ablation in Patients with Atrial Fibrillation and Chronic Kidney Disease.

BACKGROUND: Chronic kidney disease (CKD) is associated with adverse outcomes in presence of atrial fibrillation (AF). However, the literature shows limited data on non-pharmacological management of AF in CKD patients. AIM: summarizing the available data on outcomes associated with electrical cardioversion (ECV) and AF catheter ablation (CA) in CKD patients. METHODS: We searched MEDLINE and the Cochrane Central Register of Controlled Trials and performed a metaanalysis. The primary outcome was recurrence of AF. The secondary outcomes were occurrence of thromboembolic events (TEs) and estimated glomerular filtration rate (eGFR) modification. RESULTS: Literature search yielded 26 eligible papers: 22 on CA and 4 concerning ECV. CKD patients presented more AF recurrences 30 days after ECV (OR 2.62, 95%CI 1.28-5.34; p <0.001). Patients with eGFR<60-68 ml/min and on dialysis presented a higher incidence of AF recurrences after CA, median follow up 26.0 and 29.9 months (HR 1.75, 95%CI 1.46-2.09, p <0.001; and HR 1.69, 95%CI 1.22-2.33, p <0.001; respectively). Periprocedural TEs were rare and not associated with CKD or dialysis. However, patients with CKD were at increased risk for delayed TEs after CA (HR 2.61, 95%CI 1.04-6.54; p <0.001). No significant modification of eGFR was associated with ECV or CA in the overall population. CONCLUSION: ECV and CA for sinus rhythm restoration/maintenance in AF patients, albeit theoretically promising, seem to be associated with lower efficacy at medium to long-term in patients with CKD. Further studies are needed to better define the role of ECV and CA in CKD.

Ectopic Beats: Insights from Timing and Morphology.

Premature complexes are electrical impulses arising from atrial, junctional, or ventricular tissue, leading to premature heart beats. Premature atrial beats are much more frequent than those arising in the atrioventricular junction but less frequent than premature beats from the ventricles. Although they are usually benign and highly prevalent in the general population, they could trigger sustained supraventricular and ventricular arrhythmias, and cause cardiomyopathies. The aim of this article was to review the main electrocardiology features of premature complexes and discuss their implications in clinical practice.

Electrocardiogram and Imaging: An Integrated Approach to Arrhythmogenic Cardiomyopathies.

Cardiovascular imaging has radically changed the management of patients with arrhythmogenic cardiomyopathies. This article focuses on the role of echocardiography and MRI in the diagnosis of these structural diseases. Cardiomyopathies with hypertrophic pattern (hypertrophic cardiomyopathy, restrictive cardiomyopathies, amyloidosis, Anderson-Fabry disease, and sarcoidosis), cardiomyopathies with dilated pattern, inflammatory cardiac diseases, and right ventricular arrhythmogenic cardiomyopathy are analyzed. Finally, anatomic predictors of arrhythmias and sudden cardiac death are discussed. Each paragraph is attended by clinical cases that are discussed on the electrocardiogram, after integrated with the anatomic, functional, and hemodynamic modifications of cardiovascular imaging.

Complexity in internal medicine wards: A novel screening method and implications for management.

RATIONALE: Complexity is increasingly recognized as a critical variable in health care. However, there is still lack of practical tools to assess it and tackle the challenges that stem from it, particularly within hospitals. AIMS AND OBJECTIVE: To validate a simple novel screening method based on both objective and subjective criteria to identify patients with clinically complex hospitalization events. To evaluate the prevalence of patients with complex events, identify their features, and compare them with those of the other patients and to those of patients with multimorbidities. METHOD: We monitored the level of complexity of the hospitalization events of 240 patients admitted to an internal medicine ward in Tuscany over the course of 56 days. We compared the demographic features, the length of stay, and the prognosis of patients with and without complex events. RESULTS: Sixty-nine patients (28.8% of the sample) had a complex episode during their stay, and 115 (47.9%) had phases of low complexity. Patients with complex episodes were younger and more comorbid than patients without. They stayed longer in-hospital (+4.5 days; 95% CI: 2.5-6.5) and had higher mortality (OR: 24.93; 95% CI: 6.97-171.63) and a lower probability of home discharge (OR: 0.25; 95% CI: 0.13-0.48). CONCLUSIONS: The results show that using a simple screening method is possible to identify complex patients within IM wards and that every day, about one-third of the patients are complex. The results are discussed in implications for the dynamic management of patients with complex and simple phases during hospitalization.

Cardiac resynchronization therapy improves functional status and cognition.

BACKGROUND: Many trials demonstrated the beneficial effects on hospitalizations and mortality of cardiac resynchronization therapy (CRT). The purpose of this study was to evaluate CRT effects on functional performance and cognition, two determinants of disability, frailty development and survival. METHODS: All consecutive patients receiving a CRT device were evaluated at baseline and at the 6-month follow-up. Functional profile was assessed with the Short Physical Performance Battery (SPPB), a measure exploring balance, gait, strength and endurance, highly predictive of incident disability and mortality. The Mini-Mental State Examination (MMSE) was used to study the cognitive profile. RESULTS: We enrolled 54 patients; two of them died during the follow-up, two refused to continue the study. Age was 67±10years (men: 80%, LVEF: 28±5%); medical therapy was optimized (ACE-I/ARB: 84%, beta-blockers: 80%). After 6months, CRT was associated with the improvement of LVEF (35±8 vs. 28±5%, p<0.001) and NYHA Class (1.8±0.6 vs. 2.6±0.5, p<0.001), and with the reduction of left ventricular end-systolic diameter (50±9 vs. 57±9mm, p<0.001). SPPB improved in its total score (10.3±2.0 vs. 9.1±2.7, p<0.001) and in the scores exploring gait speed and strength and endurance. These changes were associated with a better cognitive profile (MMSE score: 27.0±3.5 vs. 25.9±4.8, p=0.009). Advanced age was an independent predictor of improved functional performance and cognition. CONCLUSIONS: CRT is associated with higher functional and cognitive profile after only 6months of therapy. These findings let us hypothesize a powerful effect of treatment to slow disability and frailty development in heart failure.

Simultaneous His Bundle and Left Ventricular Pacing for Optimal Cardiac Resynchronization Therapy Delivery: Acute Hemodynamic Assessment by Pressure-Volume Loops.

BACKGROUND: Previous studies have investigated the role of intrinsic conduction in optimizing cardiac resynchronization therapy. We investigated the role of fusing pacing-induced activation and intrinsic conduction in cardiac resynchronization therapy by evaluating the acute hemodynamic effects of simultaneous His-bundle (HIS) and left ventricular (LV) pacing. METHODS AND RESULTS: We studied 11 patients with systolic heart failure and left bundle-branch block scheduled for cardiac resynchronization therapy implantation. On implantation, LV pressure-volume data were determined via conductance catheter. Standard leads were placed in the right atrium, at the right ventricular apex, and in a coronary vein. An additional electrode was temporarily positioned in the HIS. The following pacing configurations were systematically assessed: standard biventricular (right ventricular apex+LV), LV-only, HIS, simultaneous HIS and LV (HIS+LV). Each configuration was compared with the AAI mode at multiple atrioventricular delays (AVD). In comparison with the AAI, right ventricular apex+LV and LV-only pacing resulted in improved stroke volume (85±32 mL and 86±33 mL versus 58±23 mL; P<0.001), stroke work, maximum pressure derivative, and systolic dyssynchrony at individually optimized AVD. The optimal AVD was close to the P-H interval in the majority of patients. By contrast, HIS-LV pacing improved hemodynamic indexes at all AVD (stroke volume >76 mL at all fixed intervals and 88±31 mL at optimal interval; all P<0.001). CONCLUSIONS: Standard right ventricular apex+LV and LV-only pacing enhanced systolic function and LV synchrony at individually optimized AVD close to the measured intrinsic P-H interval. By contrast, HIS+LV pacing yielded improvements, regardless of AVD setting. These findings support the hypothesis of the crucial role of intrinsic right ventricular conduction in optimal cardiac resynchronization therapy delivery.

Novel echocardiographic techniques for the evaluation of athletes' heart: A focus on speckle-tracking echocardiography.

BACKGROUND: The development and rapid dissemination of two-dimensional echocardiography led to important further advances in our understanding of athletes' heart that has been the subject of several echocardiographic studies involving many thousands of athletes. The description of ventricular chamber enlargement, myocardial hypertrophy and atrial dilatation has led to a more comprehensive understanding of cardiac adaptation to exercise conditioning. Most recently, advanced echocardiographic techniques have begun to clarify significant functional adaptations of the myocardium that accompany previously reported morphological features of athletes' heart. In particular, speckle-tracking echocardiography (STE) has recently provided further insights into the characterisation of myocardial properties. DISCUSSION: STE is a relatively new, largely angle-independent, non-invasive imaging technique that allows for an objective and quantitative evaluation of global and regional myocardial function. STE has enhanced our understanding of athletes' heart through a comprehensive characterisation of biventricular and biatrial function, providing novel insights into the investigation of physiological adaptation of the heart to exercise conditioning. These peculiarities can provide further useful data to distinguish between athletes' heart and cardiomyopathies. Furthermore, STE represents a promising tool to address new concerns on right ventricular function and to increase understanding of the complexity of the non-systemic circulation, especially in the athletic population. CONCLUSION: This review article analyses new data on cardiac function in athletes by novel echocardiographic techniques with a particular attention to the application of STE to characterise biventricular and biatrial function in athletes.

Chronic kidney disease and worsening renal function in acute heart failure: different phenotypes with similar prognostic impact?

Nearly a third of patients with acute heart failure experience concomitant renal dysfunction. This condition is often associated with increased costs of care, length of hospitalisation and high mortality. Although the clinical impact of chronic kidney disease (CKD) has been well established, the exact clinical significance of worsening renal function (WRF) during the acute and post-hospitalisation phases is not completely understood. Therefore, it is still unclear which of the common laboratory markers are able to identify WRF at an early stage. Recent studies comparing CKD with WRF showed contradictory results; this could depend on a different WRF definition, clinical characteristics, haemodynamic disorders and the presence of prior renal dysfunction in the population enrolled. The current definition of acute cardiorenal syndrome focuses on both the heart and kidney but it lacks precise laboratory marker cut-offs and a specific diagnostic approach. WRF and CKD could represent different pathophysiological mechanisms in the setting of acute heart failure; the traditional view includes reduced cardiac output with systemic and renal vasoconstriction. Nevertheless, it has become a mixed model that encompasses both forward and backward haemodynamic dysfunction. Increased central venous pressure, renal congestion with tubular obliteration, tubulo-glomerular feedback and increased abdominal pressure are all potential additional contributors. The impact of WRF on patients who experience preserved renal function and individuals affected with CKD is currently unknown. Therefore it is extremely important to understand the origins, the clinical significance and the prognostic impact of WRF on CKD.

Training-induced dynamic changes in left atrial reservoir, conduit, and active volumes in professional soccer players.

PURPOSE: Although left atrial (LA) enlargement is a recognized component of athlete's heart, dynamic cavity changes occurring during the training period remain to be elucidated. We aimed to investigate the adaptive changes of LA reservoir, conduit, and active volumes in elite athletes vs. controls and their response to different training loads. METHODS: LA maximum, pre-P, and minimum volumes were assessed in 26 top-level athletes and 23 controls. In athletes, LA volumes were measured at pre-, mid-, end-training, and post-detraining time points using conventional 2D echocardiography. RESULTS: Athletes had larger maximum (27.5 ± 3.2 vs. 20.3 ± 5.8 mL/m(2), p = 0.001), pre-P (11.5 ± 0.9 vs. 9.8 ± 2.2 mL/m(2), p = 0.001), and minimum (6.6 ± 0.9 vs. 5.0 ± 1.2 mL/m(2), p < 0.001) LA indexed volumes, compared with controls. Total and passive emptying volume indices were also larger in athletes compared with controls (18.7 ± 3.1 vs. 15.3 ± 4.9 mL/m(2), p < 0.05 and 13.8 ± 2.9 vs. 10.5 ± 4.6 mL/m(2), p < 0.05, respectively), while active emptying volume was similar (p = 0.74). During training, LA maximum (p < 0.0001), pre-P (p < 0.0001), minimum (p < 0.0001), total (p < 0.005), and passive (p < 0.05) emptying volume indices progressively increased, while active emptying volume (p = 0.10) and E/e' ratio (p = 0.32) remained unchanged. After detraining, LA volume measurements were not different from pre-training ones. End-training left ventricular mass index was the only independent predictor of the respective maximum LA volume (ß = 0.74, p < 0.005). CONCLUSIONS: Top-level athletes exhibit a dynamic morphological and functional LA remodeling, induced by training, with an increase in reservoir and conduit volumes, but stable active volume. LA remodeling is closely associated with left ventricular adaptation to exercise and both completely regress after detraining.

Increased left atrial size is associated with reduced atrial stiffness and preserved reservoir function in athlete's heart.

Left atrial (LA) fibrosis with increased stiffness has been assumed to be the substrates for occurrence of atrial arrhythmias in athletes. However, this hypothesis has not yet been confirmed in humans. Aim of this study was, therefore, to assess LA remodeling and stiffness in competitive athletes. 150 competitive athletes and 90 age and sex-matched sedentary subjects were analyzed by speckle-tracking echocardiography to measure peak atrial longitudinal strain (PALS) and peak atrial contraction strain (PACS). LA stiffness was determined using E/e' ratio in conjunction with PALS. Left ventricular (LV) stiffness was also calculated. LA volume index was greater in athletes as compared with controls (24.6 ± 7.3 vs. 18.4 ± 7.8 mL/m(2), p < .0001). LA PALS, LA PACS, and E/e' ratio were lower in athletes in comparison with controls (p < .05, p ≤ .001, and p < .0001, respectively). Despite greater LA size, competitive athletes had lower LA stiffness as compared with controls (0.13 ± 0.04 vs. 0.16 ± 0.06, p ≤ .001). In addition, LV stiffness was lower in athletes (0.84 ± 0.27 vs. 1.07 ± 0.46, p ≤ .001). The only independent predictor of LA stiffness was LV stiffness (ß = 0.46, p < .0001), while the only independent predictor of LA volume index was LV end-systolic volume index (ß = 0.25, p = .002). Competitive athletes showed greater LA size associated with lower stiffness as compared with controls. Thus, LA remodeling in the context of the athlete's heart is not associated with increased LA stiffness. These findings support the benign nature of LA remodeling in athletes, occurring as a physiological adaptation to exercise conditioning.

Cardiac resynchronization therapy acutely improves ventricular-arterial coupling by reducing the arterial load: assessment by pressure-volume loops.

BACKGROUND: Cardiac resynchronization therapy (CRT) has been demonstrated to improve ventricular-arterial coupling by reducing effective arterial elastance (Ea) on long-term follow-up. Detailed invasive studies showing possible acute peripheral effects of CRT are not available. We evaluated the hemodynamic effects of CRT in patients with systolic dysfunction, in order to investigate the impact on ventricular-arterial coupling and, in particular, on Ea immediately after the initiation of pacing. METHODS: We studied 37 heart failure patients undergoing CRT implantation based on conventional criteria. On implantation, left ventricular (LV) pressure and volume data were determined via a conductance catheter. Twelve patients with a standard indication for electrophysiologic study and preserved LV function served as a control group. RESULTS: In comparison with the control group, heart failure patients showed reduced systolic and diastolic function. LV end-systolic elastance (Ees: end-systolic pressure/volume) was impaired (0.79 ± 0.33 mm Hg/mL vs 1.84 ± 0.89 mm Hg/mL, P = 0.012) and Ees/Ea reduced (0.36 ± 0.17 vs 1.19 ± 1.81, P = 0.022). In heart failure patients, CRT immediately improved systolic function, increasing stroke work from 3.9 ± 1.8 L*mm Hg to 6.9 ± 3.3 L*mm Hg (P < 0.001) and Ees to 1.02 ± 0.62 mm Hg/mL (P = 0.001). Ea decreased from 2.59 ± 1.35 mm Hg/mL to 1.68 ± 0.91 mm Hg/mL (P < 0.001), leading to an increase in Ees/Ea to 0.70 ± 0.38 (P < 0.001). CONCLUSION: Our data indicate that switching CRT on induces an immediate reduction in arterial load, conceivably as a consequence of restored autonomic balance.

Simplified Selvester Score: a practical electrocardiographic instrument to predict response to CRT.

AIMS: To investigate the LBBB Selvester Scoring System (LBBB-SSc) and the Simplified-SSc prognostic impact in predicting response to CRT, all cause and cardiac mortality, heart failure (HF) hospitalizations and onset of arrhythmias in HF patients undergoing CRT. METHODS: We retrospectively evaluated LBBB-SSc and Simplified-SSc of 172 consecutive HF patients with true-LBBB who underwent CRT. Response to CRT was defined as the improvement of LVEF of at least 10% or as the reduction of LVESV of at least 15% at 6-month follow-up. Logistic regression analysis and Cox proportional hazard analysis were performed to evaluate each endpoint related risk according to LBBB-SSc and Simplified-SSc. RESULTS: The LBBB-SSc and the Simplified-SSc were inversely correlated with response to CRT. Myocardial scar at both scores was independently associated to non-response to CRT. No correlation was observed between LBBB-SSc or Simplified-SSc and other endpoints. CONCLUSIONS: In HF patients with true-LBBB, Simplified-SSc is able to predict response to CRT.

Determinants of all-cause mortality in different age groups in patients with severe systolic left ventricular dysfunction receiving an implantable cardioverter defibrillator (from the Italian ClinicalService Multicenter Observational Project).

Heart failure (HF) is a common condition in elderly patients. Despite great improvements in medical therapy, HF mortality remains high. Implantable cardioverter defibrillator (ICD) significantly lengthens the survival rate of subjects with severe HF, but little evidence exists on its effect in elderly persons. Aim of this study was to compare the age-related determinants of prognosis in a large population of patients with ICD. We divided all patients who underwent an ICD implantation in 117 Italian centers of the "ClinicalService Project" into 3 age groups (<65, 65 to 74, ≥ 75 years), and collected clinical and instrumental variables at baseline and during follow-up (median length: 27 months). Between 2004 and 2011, 6,311 patients were enrolled (5,174 men; left ventricular ejection fraction 29% ± 9%); 1,510 subjects were ≥ 75 years (23.9%; mean age 78 ± 3 years). The prevalence of co-morbidities increased with age. HF was most frequently due to coronary artery disease in the elderly, who also showed the worst New York Heart Association class. At multivariate analysis, older age, coronary artery disease, chronic obstructive pulmonary disease, chronic renal failure, diabetes, complex ventricular arrhythmias, and left ventricular ejection fraction were significant predictors of all-cause mortality. After adjustment, the hazard ratio(age group) for mortality was 22.6% less than at univariate analysis. When groups were analyzed separately, age alone predicted mortality in the oldest. In conclusion, a large proportion of our population was aged ≥ 75 years. Mortality was related to age and several co-morbidities, except for the oldest patients in whom age alone resulted predictive.

Sleep-disordered breathing increases the risk of arrhythmias.

Sleep-disordered breathing (SDB) has been consistently associated with increased risk for cardiovascular diseases, including arrhythmias. The purpose of this review is to elucidate the several pathophysiologic pathways such as repetitive hypoxia and reoxygenation, increased oxidative stress, inflammation and sympathetic activation that may underlie the increased incidence of arrhythmias in SDB patients. We discuss in particular the incidence of ventricular arrhythmias, atrial fibrillation and bradyarrhythmias in SDB patients. In addition, we discuss the electrocardiographic alteration such as ST-T changes during apneic events and QT dispersion induced by SDB that may trigger complex ventricular arrhythmias and sudden cardiac death. Finally, we consider also the therapeutic interventions such as continuous positive airways pressure therapy, a standard treatment for SDB, that may reduce the incidence and recurrence of supraventricular and ventricular arrhythmias in patients with SDB.

Metabolomic does not predict response to cardiac resynchronization therapy in patients with heart failure.

AIMS: Metabolomic, a systematic study of metabolites, may be a useful tool in understanding the pathological processes that underlie the occurrence and progression of a disease. We hypothesized that metabolomic would be helpful in assessing a specific pattern in heart failure patients, also according to the underlining causes and in defining, prior to device implantation, the responder and nonresponder patient to cardiac resynchronization therapy (CRT). METHODS: In this prospective study, blood and urine samples were collected from 32 heart failure patients who underwent CRT. Clinical, electrocardiography and echocardiographic evaluation was performed in each patient before CRT and after 6 months of follow-up. Thirty-nine age and sex-matched healthy individuals were chosen as control group. For each sample, 1H-NMR spectra, Nuclear Overhauser Enhancement Spectroscopy, Carr-Purcell-Meiboom-Gill and diffusion edited spectra were measured. RESULTS: A different metabolomic fingerprint was demonstrated in heart failure patients compared to healthy controls with high accuracy level. Metabolomics fingerprint was similar between patients with ischemic and nonischemic dilated cardiomyopathy. At 6-month follow-up, metabolomic fingerprint was different from baseline. At follow-up, heart failure patients' metabolomic fingerprint remained significantly different from that of healthy controls, and accuracy of cause discrimination remained low. Responders and nonresponders had a similar metabolic fingerprint at baseline and after 6 months of CRT. CONCLUSION: It is possible to identify a metabolomic fingerprint characterizing heart failure patients candidate to CRT, it is independent of the different causes of the disease and it is not predictive of the response to CRT.