Beta-blocker treatment of patients with atrial fibrillation attenuates spontaneous calcium release-induced electrical activity

AIMS

Atrial fibrillation (AF) has been associated with excessive spontaneous calcium release, linked to cyclic AMP (cAMP)-dependent phosphorylation of calcium regulatory proteins. Because β-blockers are expected to attenuate cAMP-dependent signaling, we aimed to examine whether the treatment of patients with β-blockers affected the incidence of spontaneous calcium release events or transient inward currents (I_TI).

METHODS

The impact of treatment with commonly used β-blockers was analyzed in human atrial myocytes from 371 patients using patch-clamp technique, confocal calcium imaging or immunofluorescent labeling. Data were analyzed using multivariate regression analysis taking into account potentially confounding effects of relevant clinical factors RESULTS: The L-type calcium current (I_Ca) density was diminished significantly in patients with chronic but not paroxysmal AF and the treatment of patients with β-blockers did not affect I_Ca density in any group. By contrast, the I_TI frequency was elevated in patients with either paroxysmal or chronic AF that did not receive treatment, and β-blocker treatment reduced the frequency to levels observed in patients without AF. Confocal calcium imaging showed that β-blocker treatment also reduced the calcium spark frequency in patients with AF to levels observed in those without AF. Furthermore, phosphorylation of the ryanodine receptor (RyR2) at Ser-2808 and phospholamban at Ser-16 was significantly lower in patients with AF that received β-blockers.

CONCLUSION

Together, our findings demonstrate that β-blocker treatment may be of therapeutic utility to prevent spontaneous calcium release-induced atrial electrical activity; especially in patients with a history of paroxysmal AF displaying preserved I_Ca density.

Electrophysiological and histological characterization of atrial scarring in a model of isolated atrial myocardial infarction

Background: Characterization of atrial myocardial infarction is hampered by the frequent concurrence of ventricular infarction. Theoretically, atrial infarct scarring could be recognized by multifrequency tissue impedance, like in ventricular infarction, but this remains to be proven. Objective: This study aimed at developing a model of atrial infarction to assess the potential of multifrequency impedance to recognize areas of atrial infarct scar. Methods: Seven anesthetized pigs were submitted to transcatheter occlusion of atrial coronary branches arising from the left coronary circumflex artery. Six weeks later the animals were anesthetized and underwent atrial voltage mapping and multifrequency impedance recordings. The hearts were thereafter extracted for anatomopathological study. Two additional pigs not submitted to atrial branch occlusion were used as controls. Results: Selective occlusion of the atrial branches induced areas of healed infarction in the left atrium in 6 of the 7 cases. Endocardial mapping of the left atrium showed reduced multi-frequency impedance (Phase angle at 307 kHz: from -17.1° ± 5.0° to -8.9° ± 2.6°, p < .01) and low-voltage of bipolar electrograms (.2 ± 0.1 mV vs. 1.9 ± 1.5 mV vs., p < .01) in areas affected by the infarction. Data variability of the impedance phase angle was lower than that of bipolar voltage (coefficient of variability of phase angle at307 kHz vs. bipolar voltage: .30 vs. .77). Histological analysis excluded the presence of ventricular infarction. Conclusion: Selective occlusion of atrial coronary branches permits to set up a model of selective atrial infarction. Atrial multifrequency impedance mapping allowed recognition of atrial infarct scarring with lesser data variability than local bipolar voltage mapping. Our model may have potential applicability on the study of atrial arrhythmia mechanisms.

Spatial Distribution of Calcium Sparks Determines Their Ability to Induce Afterdepolarizations in Human Atrial Myocytes

Analysis of the spatio-temporal distribution of calcium sparks showed a preferential increase in sparks near the sarcolemma in atrial myocytes from patients with atrial fibrillation (AF), linked to higher ryanodine receptor (RyR2) phosphorylation at s2808 and lower calsequestrin-2 levels. Mathematical modeling, incorporating modulation of RyR2 gating, showed that only the observed combinations of RyR2 phosphorylation and calsequestrin-2 levels can account for the spatio-temporal distribution of sparks in patients with and without AF. Furthermore, we demonstrate that preferential calcium release near the sarcolemma is key to a higher incidence and amplitude of afterdepolarizations in atrial myocytes from patients with AF.

Time course, factors related to, and prognostic impact of venoarterial extracorporeal membrane flow in cardiogenic shock

AIMS

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is currently one of the most used devices in refractory cardiogenic shock. However, there is a lack of evidence on how to set the 'optimal' flow. We aimed to describe the evolution of VA-ECMO flows in a cardiogenic shock population and determine the risk factors of 'high-ECMO flow'.

METHODS AND RESULTS

A 7 year database of patients supported with VA-ECMO was used. Based on the median flow during the first 48 h of the VA-ECMO run, patients were classified as 'high-flow' or 'low-flow', respectively, when median ECMO flow was ≥3.6 or <3.6 L/min. Outcomes included rates of ventilator-associated pneumonia, ECMO-related complications, days on ECMO, days on mechanical ventilation, intensive care unit and hospitalization lengths of stay, and in-hospital and 60 day mortality. Risk factors of high-ECMO flow were assessed using univariate and multivariate cox regression. The study population included 209 patients on VA-ECMO, median age was 51 (40-59) years, and 78% were males. The most frequent aetiology leading to cardiogenic shock was end-stage dilated cardiomyopathy (57%), followed by acute myocardial infarction (23%) and fulminant myocarditis (17%). Among the 209 patients, 105 (50%) were classified as 'high-flow'. This group had a higher rate of ischaemic aetiology (16% vs. 30%, P = 0.023) and was sicker at admission, in terms of worse Simplified Acute Physiology Score II score [40 (26-58) vs. 56 (42-74), P < 0.001], higher lactate [3.6 (2.2-5.8) mmol/L vs. 5.2 (3-9.7) mmol/L, P < 0.001], and higher aspartate aminotransferase [97 (41-375) U/L vs. 309 (85-939) U/L, P < 0.001], among others. The 'low-flow' group had less ventilator-associated pneumonia (40% vs. 59%, P = 0.007) and less days on mechanical ventilation [4 (1.5-7.5) vs. 6 (3-12) days, P = 0.009]. No differences were found in lengths of stay or survival according to the ECMO flow. The multivariate analysis showed that risk factors independently associated with 'high-flow' were mechanical ventilation at cannulation [odds ratio (OR) 3.9, 95% confidence interval (CI) 2.1-7.1] and pre-ECMO lactate (OR 1.1, 95% CI 1.0-1.2).

CONCLUSIONS

In patients with refractory cardiogenic shock supported with VA-ECMO, sicker patients had higher support since early phases, presenting thereafter higher rates of ventilator-associated pneumonia but similar survival compared with patients with lower flows.

A closed-chest model of selective atrial myocardial infarction for the study of induced electrophysiological and structural derangements

Background

The diagnosis of atrial infarction is often masked by the frequent association with ventricular infarction. For this reason, the electrophysiological and structural consequences of selective atrial ischemia are poorly understood.

Purpose

The objective of this study was to analyze the alterations in the ECG, local electrograms, and multifrequential atrial myocardial impedance in a new experimental model of acute and chronic atrial infarction.

Methods

Seven anesthetized pigs were subjected to 4h of atrial ischemia induced by selective catheter occlusion of the atrial coronary branches originating in the left circumflex coronary artery. The surface ECG was recorded and the changes in P-wave morphology analyzed. Four weeks later the animals were subjected to endocardial voltage mapping (Carto) and multifrequential impedance. The hearts were processed for anatomopathological study.

Results

Selective occlusion of the coronary atrial branches induced atrial infarction with fibrosis in the left atrium in 6 of the 7 cases (Figure). The surface ECG showed prolongation of the P-wave duration (Figure) (P-wave in lead II: from 72±8ms at baseline vs. 97±18ms at 4 weeks, ANOVA p&lt;0.01; P-wave in lead aVR: from 71±3ms at baseline vs 87±9ms at 4 weeks, ANOVA p&lt;0.01) with no appreciable displacement of the PR segment. Endocardial mapping of the left atrium showed low-voltage bipolar zones with decreased multi-frequency impedance phase angle values, as compared with preserved zones of the same atrium (bipolar electrograms: from 0.6±1mV to 2.0±1.9mV, T-Test p&lt;0.01; Phase angle at 300KHz: from −5.5±2° to −9.0±4.4° T-Test p&lt;0.05).

Conclusion

We developed a closed-chest swine model of selective atrial infarction suitable for the study of ECG patterns and electrophysiological mechanisms linked to atrial myocardial ischemia and infarction. The structural derangements are detectable by endocardial mapping of local voltage electrograms and local tissue impedance.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Supported by grants from ISCI-MINECO (FIS PI17/00069), FEDER, CIBERCV (CB16/11/00276)

Differential electrocardiographic changes related to the culprit coronary artery in patients with acute myocardial infarction and left bundle branch block

Background

The electrocardiographic (ECG) recognition of acute myocardial infarction (AMI) in patients with concurrent left bundle branch block (LBBB) is hampered by background changes in QRS complex duration and ST segment, potential directly caused by LBBB. Currently available ECG algorithms were constructed to suspect the presence of AMI but they not take into a count the culprit coronary artery and this fact could explain their low sensitivity.

Objectives

To analyze the influence of the culprit coronary artery on the ECG changes and on the diagnostic yielding of ECG algorithms in patients with acute myocardial infarction and LBBB.

Methods

We analyzed the index ECG of 240 patients with acute chest pain and LBBB referred to emergent coronary angiography. Patients were classified in 3 groups according their coronary anatomy: a) acute coronary occlusion (n=48); b) critical non occlusive lesion (n=45); and c) absence of coronary lesions (n=76). In all ECGs we measured the ST-segment shifts and QRS duration and compared the pattern of changes in relation to the culprit coronary artery.

Results

Location of the culprit coronary artery induced differential ECG patterns: a) mean ST segment elevation ≥3mm in leads V2-V3 in patients with LAD occlusion (n=27); b) absence of ST segment depression in leads V5-V6 in LCX occlusion (n=11); and c) mean ST segment elevation ≥1.5 mm in leads III-aVF and attenuation of the ST elevation in leads V1-V2 (mean &lt;1mm) in cases of RCA occlusion (n=10). Patients with critical non occlusive lesions (n=45) did not show particular ECG changes. QRS complex duration was longer in patients with LCX occlusion. Sensitivity of the Sgarbossa score was around 50%, sensitivity of the Smith score was &gt;70% in all coronary groups and sensitivity of Barcelona score was really good for LCX and RCA occlusion. The combination of the three algorithms increased the sensitivity in all groups (&gt;74%) but more markedly in patients with LCX occlusion (90.9%) and RCA occlusion (90%). All the ECG algorithms lose sensitivity for the critical non occlusive lesions group.

Conclusions

Patients with acute myocardial infarction and LBBB present distinct patterns of QRS and ST segment changes and different diagnostic yielding of ECG algorithms in relation to the location of the occluded coronary artery. Data suggest that ECG prediction of the culprit coronary artery in patients with AMI and LBBB might be possible using artificial intelligence systems in larger series of patients.

Funding Acknowledgement

Type of funding sources: None.

Real-time electrophysiological characterization of acute and chronic radiofrequency ablation lesions

Background

Assessment of lesion formation remains one of the most important goals to guide radiofrequency (RF) procedures in the cardiac electrophysiology laboratory. Cardiac navigation systems use specific algorithms to predict the effective lesion size, but these metrics are based only on ablation parameters and ignore local electric tissue characteristics. [1] Recent studies show that local multiparametric impedance is influenced by the intrinsic structural characteristics of the tissue. [2]

Purpose

This study aimed to assess the ability of local multiparametric impedance to characterize acute and chronic RF ablation lesions in the right atrium of pigs.

Methods

Four anesthetized closed-chest pigs were submitted to two interventions. The first intervention aimed at creating RF ablation lesions (30W, 60s, 55°) in the right atrium using an electrocatheter connected to a conventional cardiac navigation system, while mapping the local multiparametric impedance (LMI), the generator impedance (GI) and the bipolar voltage (BiV). All RF ablation lesions were performed with a stable contact force. Four weeks later, the second intervention aimed at mapping again the previous ablation sites. After the second intervention animals were euthanized and the hearts were removed and processed to identify the presence of fibrosis in the previously ablated lesions (Figure).

Results

We performed 19 ablations (5±2 per animal) with an average contact force of 14.2±4.6g. Four weeks later, 14/19 (74%) ablation lesions were identified as fibrotic points in the explanted heart (Figure 1). These showed decreased acute LMI and BiV values that persisted low after 4 weeks (Table 1). The remaining 5/19 ablations that did not present fibrosis had lower baseline LMI and bipolar values that resulted in lower LMI and BiV drops (Table 1). The absolute drop in LMI between effective and non-effective lesions was around 50%, while GI drop was only 21% (LMI drop @51KHz: From −3.0±1.4° to −1.5±0.3°, T-TEST p&lt;0.05; GI drop: From 12.7±27.6Ω to 10.5±21.3Ω, T-TEST p=0.89).

Conclusion

The local baseline electrical properties of atrial myocardium are directly related to the effectiveness of RF ablation lesions. RF ablation sites that resulted into persistent fibrosis points had larger LMI and BiV values, with higher absolute drops than non-effective lesions. The use of LMI in clinical practice could improve the outcome of the procedures of arrhythmia ablation in the electrophysiology lab.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Supported by grants from ISCI-MINECO (FIS PI21/00392), FEDER, CIBERCV (CB16/11/00276)

Incremental prognostic value of lung ultrasound on contemporary heart failure risk scores

Introduction: Over the last decades, several scores have been developed to aid clinicians in assessing prognosis in patients with heart failure (HF) based on clinical data, medications and, ultimately, biomarkers. Lung ultrasound (LUS) has emerged as a promising prognostic tool for patients when assessed at discharge after a HF hospitalization. We hypothesized that contemporary HF risk scores can be improved upon by the inclusion of the number of B-lines detected by LUS at discharge to predict death, urgent visit, or HF readmission at 6- month follow-up.

Methods: We evaluated the discrimination improvement of adding the number of B-lines to 4 contemporary HF risk scores (Get with the Guidelines -GWTG-, MAGGIC, Redin-SCORE, and BCN Bio-HF) by comparing the change in the area under the receiver operating curve (AUC), the net reclassification index (NRI), and the integrated discrimination improvement (IDI). The population of the study was constituted by the 123 patients enrolled in the LUS-HF trial, adjusting the analyses by the intervention.

Results: The AUC of the GWTG score increased from 0.682 to 0.789 (p = 0.02), resulting in a NRI of 0.608 and an IDI of 0.136 (p < 0.05). Similar results were observed when adding the number of B-lines to the MAGGIC score, with an AUC that increased from 0.705 to 0.787 (p < 0.05). This increase translated into a NRI of 0.608 and an IDI of 0.038 (p < 0.05). Regarding Redin-SCORE at 1-month and 1-year, the AUC increased from 0.714 to 0.773 and from 0.681 to 0.757, although it did not reach statistical significance (p = 0.08 and p = 0.06 respectively). Both IDI and NRI were significantly improved (0.093 and 0.509 in the 1-month score, p < 0.05; 0.056 and 0.111 in the 1-year score, p < 0.05). Lastly, the AUC for the BCN Bio-HF score increased from 0.733 to 0.772, which was statistically non-significant, with a NRI value of 0.363 (p = 0.06) and an IDI of 0.092 (p < 0.05).

Conclusion: Adding the results of LUS evaluated at discharge improved the predictive value of most of the contemporary HF risk scores. As it is a simple, fast, and non-invasive test it may be recommended to assess prognosis at discharge in HF patients.

β2-adrenergic stimulation potentiates spontaneous calcium release by increasing signal mass and co-activation of ryanodine receptor clusters

AIMS

It is unknown how β-adrenergic stimulation affects calcium dynamics in individual RyR2 clusters and leads to the induction of spontaneous calcium waves. To address this, we analysed spontaneous calcium release events in green fluorescent protein (GFP)-tagged RyR2 clusters.

METHODS

Cardiomyocytes from mice with GFP-tagged RyR2 or human right atrial tissue were subjected to immunofluorescent labelling or confocal calcium imaging.

RESULTS

Spontaneous calcium release from single RyR2 clusters induced 91.4% ± 2.0% of all calcium sparks while 8.0% ± 1.6% were caused by release from two neighbouring clusters. Sparks with two RyR2 clusters had 40% bigger amplitude, were 26% wider, and lasted 35% longer at half maximum. Consequently, the spark mass was larger in two- than one-cluster sparks with a median and interquartile range for the cumulative distribution of 15.7 ± 20.1 vs 7.6 ± 5.7 a.u. (P < .01). β2-adrenergic stimulation increased RyR2 phosphorylation at s2809 and s2815, tripled the fraction of two- and three-cluster sparks, and significantly increased the spark mass. Interestingly, the amplitude and mass of the calcium released from a RyR2 cluster were proportional to the SR calcium load, but the firing rate was not. The spark mass was also higher in 33 patients with atrial fibrillation than in 36 without (22.9 ± 23.4 a.u. vs 10.7 ± 10.9; P = .015).

CONCLUSIONS

Most sparks are caused by activation of a single RyR2 cluster at baseline while β-adrenergic stimulation doubles the mass and the number of clusters per spark. This mimics the shift in the cumulative spark mass distribution observed in myocytes from patients with atrial fibrillation.

A 3-Biomarker 2-Point-Based Risk Stratification Strategy in Acute Heart Failure

Introduction and Objectives: Most multi-biomarker strategies in acute heart failure (HF) have only measured biomarkers in a single-point time. This study aimed to evaluate the prognostic yielding of NT-proBNP, hsTnT, Cys-C, hs-CRP, GDF15, and GAL-3 in HF patients both at admission and discharge. Methods: We included 830 patients enrolled consecutively in a prospective multicenter registry. Primary outcome was 12-month mortality. The gain in the C-index, calibration, net reclassification improvement (NRI), and integrated discrimination improvement (IDI) was calculated after adding each individual biomarker value or their combination on top of the best clinical model developed in this study (C-index 0.752, 0.715-0.789) and also on top of 4 currently used scores (MAGGIC, GWTG-HF, Redin-SCORE, BCN-bioHF). Results: After 12-month, death occurred in 154 (18.5%) cases. On top of the best clinical model, the addition of NT-proBNP, hs-CRP, and GDF-15 above the respective cutoff point at admission and discharge and their delta during compensation improved the C-index to 0.782 (0.747-0.817), IDI by 5% (p < 0.001), and NRI by 57% (p < 0.001) for 12-month mortality. A 4-risk grading categories for 12-month mortality (11.7, 19.2, 26.7, and 39.4%, respectively; p < 0.001) were obtained using combination of these biomarkers. Conclusion: A model including NT-proBNP, hs-CRP, and GDF-15 measured at admission and discharge afforded a mortality risk prediction greater than our clinical model and also better than the most currently used scores. In addition, this 3-biomarker panel defined 4-risk categories for 12-month mortality.

Prognostic impact of hyponatraemia and hypernatraemia at admission and discharge in heart failure patients with preserved, mid-range and reduced ejection fraction

BACKGROUND

Hyponatraemia is common in patients with acute heart failure (HF).

AIMS

To determine the impact of sodium disturbances on mortality and readmissions in HF with reduced left ventricular ejection fraction (HFrEF), preserved ejection fraction (HFpEF) and mid-range ejection fraction (HFmrEF).

METHODS

This study was a prospective multicentre consecutive registry in 20 hospitals, including patients admitted due to acute HF in cardiology departments. Sodium <135 mmol/L was considered hyponatraemia, >145 mmol/L hypernatraemia and 135-145 mmol/L normal.

RESULTS

A total of 1309 patients was included. Mean age was 72.0 ± 11.9 years, and 810 (61.9%) were male. Mean serum sodium level was 138.6 ± 4.7 mmol/L at hospital admission and 138.1 ± 4.1 mmol/L at discharge. The evolution of sodium levels was: normal-at-admission/normal-at-discharge 941 (71.9%), abnormal-at-admission/normal-at-discharge 127 (9.7%), normal-at-admission/abnormal-at-discharge 155 (11.8%) and abnormal-at-admission/abnormal-at-discharge 86 (6.6%). Hyponatraemia at discharge was more common in HFrEF (109 (20.7%)) than in HFpEF (79 (13.9%)) and HFmrEF (27 (12%)), P = 0.003. The prevalence of hypernatraemia at discharge was similar in the three groups: HFrEF (10 (1.9%)), HFpEF (12 (2.1%)) and HFmrEF (4 (1.9%)), P = 0.96. In multivariate analysis, abnormal sodium concentrations at hospital admission (hazard ratio (HR) 1.42, 95% confidence interval (CI) 1.15-1.76, P = 0.001) and discharge (HR 1.33, 95% CI 1.08-1.64, P = 0.007) were both independently associated with increased mortality and readmissions at 12 months.

CONCLUSIONS

Hyponatraemia and hypernatraemia at admission and discharge predict a poor outcome in patients with acute HF regardless of left ventricular ejection fraction. Hyponatraemia at discharge is more frequent in HFrEF than in the other groups.

Awake venoarterial extracorporeal membrane oxygenation for refractory cardiogenic shock

BACKGROUND 

Venoarterial-extracorporeal membrane oxygenation (VA-ECMO) is currently one of the first-line therapies for refractory cardiogenic shock (CS), but its applicability is undermined by the high morbidity associated with its complications, especially those related to mechanical ventilation (MV). We aimed to assess the prognostic impact of keeping patients in refractory CS awake at cannulation and during the VA-ECMO run.

METHODS 

A 7-year database of patients given peripheral VA-ECMO support was used to conduct a propensity-score (PS)-matched analysis to balance their clinical profiles. Patients were classified as 'awake ECMO' or 'non-awake ECMO', respectively, if invasive MV was used during ≤50% or >50% of the VA-ECMO run. Primary outcomes included ventilator-associated pneumonia and ECMO-related complication rates, and secondary outcomes were 60-day and 1-year mortality. A multivariate logistic-regression analysis was used to identify whether MV at cannulation was independently associated with 60-day mortality.

RESULTS 

Among 231 patients included, 91 (39%) were 'awake' and 140 (61%) 'non-awake'. After PS-matching adjustment, the 'awake ECMO' group had significantly lower rates of pneumonia (35% vs. 59%, P = 0.017), tracheostomy, renal replacement therapy, and less antibiotic and sedative consumption. This strategy was also associated with reduced 60-day (20% vs. 41%, P = 0.018) and 1-year mortality rates (31% vs. 54%, P = 0.021) compared to the 'non-awake' group, respectively. Lastly, MV at ECMO cannulation was independently associated with 60-day mortality.

CONCLUSION 

An 'awake ECMO' management in VA-ECMO-supported CS patients is feasible, safe, and associated with improved short- and long-term outcomes.

Modes of death in heart failure according to age, sex and left ventricular ejection fraction

Modes of death in patients with heart failure (HF) have been well characterized in randomized studies, but data from real-life are scarce, especially in the elderly, women and in HF with mid-range or preserved left ventricular ejection fraction (LVEF). Our purpose was to examine modes of death in HF patients according to age, sex and LVEF. We analysed the mode of death of HF patients from two prospective multicentre contemporary Spanish registries conducted by cardiologists (REDINSCOR, n = 2150) and by internists (RICA, n = 1396). Mode of death was pre-specified. Out of 3546 patients, 485 (13.7%) died during the 9-month follow-up. Cardiovascular (CV) causes were the most frequent, regardless of the age, sex and LVEF. More than half of patients died due to worsening HF in both groups of patients, followed by other non-CV causes in those attended by internists, and sudden cardiac death in those cared by cardiologists. Stroke was more common among elderly patients, women and HF with preserved LVEF. Non-CV causes, particularly infectious diseases, accounted for a remarkable proportion of deaths, especially in the elderly and in HF patients with preserved LVEF. Functional class, age and anaemia had a strong influence on both CV and non-CV death. CV death due to refractory HF was the most prevalent among our population, irrespective of age, sex or LVEF. However, a significant proportion of HF patients died from non-CV causes, particularly elderly with mid-range and preserved LVEF. These patients could benefit significantly from a multidisciplinary follow-up.

Influence of sex on intracellular calcium homeostasis in patients with atrial fibrillation

Aims

Atrial fibrillation (AF) has been associated with intracellular calcium disturbances in human atrial myocytes, but little is known about the potential influence of sex and we here aimed to address this issue.

Methods and results

Alterations in calcium regulatory mechanisms were assessed in human atrial myocytes from patients without AF or with long-standing persistent or permanent AF. Patch-clamp measurements revealed that L-type calcium current (I_Ca) density was significantly smaller in males with than without AF (−1.15 ± 0.37 vs. −2.06 ± 0.29 pA/pF) but not in females with AF (−1.88 ± 0.40 vs. −2.21 ± 0.0.30 pA/pF). In contrast, transient inward currents (I_Ti) were more frequent in females with than without AF (1.92 ± 0.36 vs. 1.10 ± 0.19 events/min) but not in males with AF. Moreover, confocal calcium imaging showed that females with AF had more calcium spark sites than those without AF (9.8 ± 1.8 vs. 2.2 ± 1.9 sites/µm²) and sparks were wider (3.0 ± 0.3 vs. 2.2 ± 0.3 µm) and lasted longer (79 ± 6 vs. 55 ± 8 ms), favouring their fusion into calcium waves that triggers I_TIs and afterdepolarizations. This was linked to higher ryanodine receptor phosphorylation at s2808 in women with AF, and inhibition of adenosine A_2A or beta-adrenergic receptors that modulate s2808 phosphorylation was able to reduce the higher incidence of I_TI in women with AF.

Conclusion

Perturbations of the calcium homoeostasis in AF is sex-dependent, concurring with increased spontaneous SR calcium release-induced electrical activity in women but not in men, and with diminished I_Ca density in men only.

Treatment with beta-blockers normalizes RyR2 phosphorylation and calcium spark activity in atrial myocytes from patients with atrial fibrillation

Background

Atrial fibrillation has been associated with an increase in ryanodine receptor (RyR2) phosphorylation and local calcium release (calcium sparks). Carvedilol, a nonselective beta-adrenergic receptor blocker also inhibits the cardiac ryanodine receptor (RyR2), but it has been suggested that the enantiomer R-carvedilol only inhibits RyR2 activity and hence has the potential to inhibit calcium sparks without affecting RyR2 phosphorylation.

Purpose

This study aimed to determine the ability of the enantiomers R- and S-carvedilol to reverse RyR2 phosphorylation at s2808 and calcium sparks induced by the β2-adrenergic agonist fenoterol, in order to determine the relationship between RyR2 phosphorylation at s2808 and calcium spark frequency, and to assess the efficacy of R- and S-carvedilol.

Methods

Human right atrial myocytes were isolated and subjected to immunofluorescent labelling of total and s2808 phosphorylated RyR2, or loaded with fluo-4 and subjected to confocal calcium imaging. Beta-adrenergic receptors were first activated with 3μM fenoterol and then inhibited by different concentrations of carvedilol R- or S-enantiomers.

Results

Incubation of myocytes with fenoterol increased the s2808/RyR2 ratio from 0.32±0.03 to 0.66±0.05 (n=18, p&lt;0.001). Incubation with 0.1, 0.3, 1 or 3μM R-carvedilol in the presence of fenoterol changed the s2808/RyR2 ratio to 0.64±0.05, 0.44±0.04, 0.34±0.07 and 0.28±0.05 (p&lt;0.01) respectively. For comparison 3μM S-carvedilol reduced the s2808/RyR2 ratio to 0.23±0.06 in myocytes from 5 patients (p&lt;0.01). Confocal calcium imaging revealed that fenoterol increased the spark density from 0.28±0.04 to 1.24±0.25 events/s/1000μm2 (n=9, p&lt;0.01) and addition of 0.1, 0.3, or 1μM R-carvedilol changed the frequency to 1.32±0.52, 0.38±0.05, and 0.15±0.05 events/s/1000μm2 (p&lt;0.01) respectively. Analysis of atrial myocytes from patients without atrial fibrillation revealed that the s2808/RyR2 ratio was similar in 25 patients treated with beta-blockers (0.39±0.04) and 57 that did not receive beta-blockers (0.44±0.03, p=0.33) while the s2808/RyR2 ratio was significantly smaller in 16 patients with atrial fibrillation receiving beta-blockers (0.43±0.08) than in 5 patients that did not (0.80±0.19, p&lt;0.05).

Conclusions

R-carvedilol reverses the effects of beta-adrenergic stimulation on s2808 phosphorylation and calcium sparks in human atrial myocytes, and treatment with beta-blockers reduces excessive RyR2 phosphorylation at s2808 in patients with atrial fibrillation to levels observed in those without the arrhythmia, pointing to beta-adrenergic receptors as a target for controlling RyR2 phophorylation and activity in atrial fibrillation.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Spanish Ministry of Science and Innovation & Spanish Ministry of Health and Consume

Pathological phosphorylation of the ryanodine receptor at s2808 increases the number of individual clusters activated per calcium spark and the calcium released per cluster

Background

Atrial fibrillation (AF) has been associated with an increase in ryanodine receptor (RyR2) phosphorylation and local calcium release (sparks), but it is not known how calcium dynamics of individual RyR2 clusters affect spark dimensions and properties.

Purpose

This study aimed to test the hypothesis that pathological alterations in the phosphorylation of individual RyR2 clusters at s2808 facilitate the fusion of spontaneous calcium release events from neighboring RyR2 clusters.

Methods

Cardiomyocytes from mice with GFP-tagged RyR2 or human right atrial tissue were subjected to confocal calcium imaging or immunofluorescent labelling of total and s2808 phosphorylated RyR2. Calcium signals were measured at a frame rate of 240 Hz in a 0.5 x 0.5 μm region of interest (ROI) for each GFP-tagged RyR2 cluster and spontaneous calcium release events were detected using a custom-made algorithm.

Results

Calcium sparks recorded in 41 myocytes with GFP-tagged RyR2s was due to the spontaneous opening of a single RyR2 cluster in 91.2±2.2% of the cells and two neighbouring clusters in (6.2±1.6%) of the cells. Events with two clusters had bigger amplitude (0.14±0.01 vs. 0.10±0.01, p&lt;0.05), were wider (1.43±0.03 vs. 1.13±0.04 μm, p&lt;0.05), and lasted longer at half maximum (59.8±5.2 vs. 44.4±2.4 ms, p&lt;0.01). Consequently, the calcium spark mass, measured as the time integral of the spark in each ROI increased from 9.2±1.6 for 1 cluster to 17.8±3.5 a.u. for 2 clusters (p&lt;0.01). Interestingly, sparks lasted longer (79±5 vs. 61±4 ms, p&lt;0.001) were wider (3.0±0.2 vs. 2.2±0.1 μm, p&gt;0.001) and had bigger mass (31.5±3.3 vs. 21.9±3.3 a.u, p&lt;0.01) in atrial myocytes from 21 patients with AF than in 27 without. Because phosphorylation of RyR2 clusters at s2808 (s2808/total RyR2) was higher in patients with than without AF (0.80±0.19 vs. 0.44±0.03, p&lt;0.05), we tested how stimulation of RyR2 phosphorylation at s2808 with the β2-adrenergic agonist fenoterol (3μM) affected calcium release in individual RyR2 clusters. Fenoterol increased s2808 phosphoryaltion from 0.39±0.05 to 0.79±0.16 (p&lt;0.05, n=9). It also increased the mass of sparks with 1 RyR2 cluster (from 9.2±1.1 to 16.0±2.3 a.u., p&lt;0.01) and sparks with 2 clusters from 17.8±3.5 to 23.6±2.7 a.u. Moreover, it increased the fraction of sparks with 2 clusters from 6.2±1.6% to 19.3±3.3% (p&lt;0.01) and sparks with 3 clusters reached 6.3±1.9% in the presence of fenoterol.

Conclusions

The calcium spark mass recorded in patients without AF is comparable to that recorded during activation of calcium release from one or two GFP-tagged RyR2 clusters. The larger mass and slower kinetics of sparks recorded in patients with AF is compatible with an increase in the calcium released from each RyR2 cluster and a 3-fold increase in sparks with 2 or 3 RyR2 clusters observed in GFP-tagged RyR2s when phosphorylation at s2808 is increased to levels observed in atrial fibrillation.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Spanish Ministry of Science and Innovation; Generatlitat de Catalunya

Prevalence and prognostic impact of subclinical pulmonary congestion at discharge in patients with acute heart failure

Aims

Residual pulmonary congestion at hospital discharge can worsen the outcomes in patients with heart failure (HF) and can be detected by lung ultrasound (LUS). The aim of this study was to analyse the prevalence of subclinical pulmonary congestion at discharge and its impact on prognosis in patients admitted for acute HF.

Methods and results

This is a post‐hoc analysis of the LUS‐HF trial. LUS was performed by the investigators in eight chest zones with a pocket device. Physical exam was subsequently performed by the treating physicians. Primary outcome was a combined endpoint of rehospitalization, unexpected visit for HF worsening or death at 6‐ month follow‐up. Subclinical pulmonary congestion at discharge was defined as the presence of ≥5 B‐lines in LUS in absence of rales in the auscultation employing the area under the ROC curve. At discharge, 100 patients (81%) did not show clinical signs of pulmonary congestion. Of these, 41 had ≥5 B‐lines. Independent factors related with the presence of subclinical pulmonary congestion were anaemia, higher New York Heart Association (NYHA) class, and N terminal pro brain natriuretic peptide (NT‐proBNP). After adjusting by propensity score analysis including age, renal insufficiency, atrial fibrillation, NYHA class, NT‐proBNP levels, clinical congestion, and the trial intervention, the presence of subclinical pulmonary congestion at discharge was a risk factor for the occurrence of the primary outcome (hazard ratio 2.63; 95% confidence interval: 1.08–6.41; P = 0.033).

Conclusions

Up to 40% of patients considered ‘dry’ according to pulmonary auscultation presents subclinical congestion at hospital discharge that can be detected by LUS and implies a worse prognosis at 6‐ month follow‐up. Comorbidities, high values of natriuretic peptides, and higher NYHA class are the factors related with its presence.

New Electrocardiographic Algorithm for the Diagnosis of Acute Myocardial Infarction in Patients With Left Bundle Branch Block

Background

Current electrocardiographic algorithms lack sensitivity to diagnose acute myocardial infarction (AMI) in the presence of left bundle branch block.

Methods and Results

A multicenter retrospective cohort study including consecutive patients with suspected AMI and left bundle branch block, referred for primary percutaneous coronary intervention between 2009 and 2018. Pre‐2015 patients formed the derivation cohort (n=163, 61 with AMI); patients between 2015 and 2018 formed the validation cohort (n=107, 40 with AMI). A control group of patients without suspected AMI was also studied (n=214). Different electrocardiographic criteria were tested. A total of 484 patients were studied. A new electrocardiographic algorithm (BARCELONA algorithm) was derived and validated. The algorithm is positive in the presence of ST deviation ≥1 mm (0.1 mV) concordant with QRS polarity, in any lead, or ST deviation ≥1 mm (0.1 mV) discordant with the QRS, in leads with max (R|S) voltage (the voltage of the largest deflection of the QRS, ie, R or S wave) ≤6 mm (0.6 mV). In both the derivation and the validation cohort, the BARCELONA algorithm achieved the highest sensitivity (93%–95%), negative predictive value (96%–97%), efficiency (91%–94%) and area under the receiver operating characteristic curve (0.92–0.93), significantly higher than previous electrocardiographic rules (P<0.01); the specificity was good in both groups (89%–94%) as well as the control group (90%).

Conclusions

In patients with left bundle branch block referred for primary percutaneous coronary intervention, the BARCELONA algorithm was specific and highly sensitive for the diagnosis of AMI, leading to a diagnostic accuracy comparable to that obtained by ECG in patients without left bundle branch block.

Estimated Population Prevalence of Heart Failure with Reduced Ejection Fraction in Spain, According to DAPA-HF Study Criteria

Heart failure (HF) is one of the main causes of morbidity, mortality, and high healthcare costs. Dapagliflozin, a sodium-glucose cotransporter-2 (SGLT2) inhibitor, reduced cardiovascular mortality and hospitalization for HF compared to placebo in patients with chronic HF, and reduced ejection fraction (EF) in the Dapagliflozin and Prevention of Adverse Outcomes in Heart Failure (DAPA-HF) study. Our aim was to estimate the number of patients with DAPA-HF characteristics in Spain. Our literature review identified epidemiological studies whose objective was to quantify the prevalence of HF and its comorbidities in Spain. We estimated the prevalence of HF with reduced EF, of New York Heart Association (NYHA) functional class II–IV, and with a glomerular filtration rate (GFR) ≥ 30 mL/min/1.73 m². In this population, we analysed the prevalence of diabetes using data from the REDINSCOR (Spanish Network for Heart Failure) registry. Our estimations indicate there are 594,684 patients ≥45 years old with HF in Spain (2.6% of this population age group), of which 52.4%, 84.0%, and 93.9% have reduced EF, are NYHA II–IV, and have a GFR ≥ 30 mL/min/1.73 m², respectively. By our calculations, approximately 245,789 Spanish patients would meet the DAPA-HF patient profile, and therefore could benefit from the protective cardiovascular effects of dapagliflozin.

Changes in causes of death and influence of therapeutic improvement over time in patients with heart failure and reduced ejection fraction

INTRODUCTION AND OBJECTIVES

In patients with heart failure and reduced ejection fraction (HFrEF), several therapies have been proven to reduce mortality in clinical trials. However, there are few data on the effect of the use of evidence-based therapies on causes of death in clinical practice.

METHODS

This study included 2351 outpatients with HFrEF (< 40%) from 2 multicenter prospective registries: MUSIC (n=641, period: 2003-2004) and REDINSCOR I (n=1710, period: 2007-2011). Variables were recorded at inclusion and all patients were followed-up for 4 years. Causes of death were validated by an independent committee.

RESULTS

Patients in REDINSCOR I more frequently received beta-blockers (85% vs 71%; P <.001), mineralocorticoid antagonists (64% vs 44%; P <.001), implantable cardioverter-defibrillators (19% vs 2%; P <.001), and resynchronization therapy (7.2% vs 4.8%; P=.04). In these patients, sudden cardiac death was less frequent than in those in MUSIC (6.8% vs 11.4%; P <.001). After propensity score matching, we obtained 2 comparable populations differing only in treatments (575 vs 575 patients). In patients in REDINSCOR I, we found a lower risk of total mortality (HR, 0.70; 95%CI, 0.57-0.87; P=.001) and sudden cardiac death (sHR, 0.46; 95%CI, 0.30-0.70; P <.001), and a trend toward lower mortality due to end-stage HF (sHR, 0.73; 95%CI, 0.53-1.01; P=.059), without differences in other causes of death (sHR, 1.17; 95%CI, 0.78-1.75; P=.445), regardless of functional class.

CONCLUSIONS

In ambulatory patients with HFrEF, implementation of evidence-based therapies was associated with a lower risk of death, mainly due to a significant reduction in sudden cardiac death.

Discharge treatment with angiotensin-converting enzyme inhibitor/angiotensin receptor blocker after a heart failure hospitalisation is associated with a better prognosis irrespective of left ventricular ejection fraction

BACKGROUND

Medical therapy could improve the prognosis of real-life patients discharged after a heart failure (HF) hospitalisation.

AIM

To determine the impact of discharge HF treatment on mortality and readmissions in different left ventricular ejection fraction (LVEF) groups.

METHODS

Multicentre prospective registry in 20 Spanish hospitals. Patients were enrolled after a HF hospitalisation.

RESULTS

A total of 1831 patients was included (583 (31.8%) HF with reduced ejection fraction (HFrEF); 227 (12.4%) HF with midrange ejection fraction (HFmrEF); 610 (33.3%) HF with preserved ejection fraction (HFpEF), and 411 (22.4%) with unknown LVEF). Angiotensin-converting enzyme (ACE) inhibitors/angiotensin II receptor blockers (ARB) at discharge were independently associated with a reduction in: (i) all-cause mortality: hazard ratio (HR) 0.55, 95% confidence interval (CI) 0.41-0.74, P < 0.001, with a similar effect in the four groups; (ii) mortality due to refractory HF HR 0.45, 95% CI 0.29-0.64, P < 0.001, with a similar effect in the three groups with known LVEF; (iii) mortality/HF admissions (HR 0.61; 95% CI: 0.50-0.74), more evident in HFrEF (HR 0.54; 95% CI: 0.38-0.78) compared with HRmEF (HR 0.64; 95% CI 0.40-1.02), or HFpEF (HR 0.70; 95% CI 0.53-0.92). In patients with HFrEF triple therapy (ACE inhibitor/ARB + beta blocker + mineralocorticoid receptor antagonist) was associated with the lowest mortality risk (HR 0.21; 95% CI: 0.08-0.57, P = 0.002) compared with patients that received none of these drugs.

CONCLUSIONS

Discharge treatment with ACE inhibitor/ARB after a HF hospitalisation is associated with a reduction in all-cause and refractory HF mortality, irrespective of LVEF.

Changes in Local Atrial Electrograms and Surface ECG Induced by Acute Atrial Myocardial Infarction

Background

Atrial coronary branch occlusion is a hardly recognizable clinical entity that can promote atrial fibrillation. The low diagnostic accuracy of the ECG could deal with the characteristics of the ischemia-induced changes in local atrial electrograms, but these have not been described.

Objectives

We analyzed the effects of selective acute atrial branch occlusion on local myocardial structure, atrial electrograms, and surface ECG in an experimental model close to human cardiac anatomy and electrophysiology.

Methods

Six anesthetized open-chest anesthetized pigs underwent surgical occlusion of an atrial coronary branch arising from the right coronary artery during 4 h. Atrial electrograms and ECG were simultaneously recorded. One additional pig acted as sham control. In all cases, the hearts were processed for anatomopathological analysis.

Results

Atrial branch occlusion induced patchy atrial necrosis with sharp border zone. During the first 30 min of occlusion, atrial electrograms showed progressive R wave enlargement (1.8 ± 0.6 mV vs. 2.5 ± 1.1 mV, p < 0.01), delayed local activation times (28.5 ± 8.9 ms vs. 36.1 ± 16.4 ms, p < 0.01), ST segment elevation (-0.3 ± 0.3 mV vs. 1.0 ± 1.0 mV, p < 0.01), and presence of monophasic potentials. Atrial ST segment elevation decreased after 2 h of occlusion. The electrical border zone was ∼1 mm and expanded over time. After 2 h of occlusion, the ECG showed a decrease in P wave amplitude (from 0.09 ± 0.04 mV to 0.05 ± 0.04 mV after 165 min occlusion, p < 0.05) and duration (64.4 ± 8.0 ms vs. 80.9 ± 12.6 ms, p < 0.01).

Conclusion

Selective atrial branch occlusion induces patchy atrial infarction and characteristic changes in atrial activation, R/S wave, and ST segment that are not discernible at the ECG. Only indirect changes in P wave amplitude and duration were appreciated in advanced stages of acute coronary occlusion.

The 4q25 variant rs13143308T links risk of atrial fibrillation to defective calcium homoeostasis

AIMS

Single nucleotide polymorphisms on chromosome 4q25 have been associated with risk of atrial fibrillation (AF) but the exiguous knowledge of the mechanistic links between these risk variants and underlying electrophysiological alterations hampers their clinical utility. Here, we tested the hypothesis that 4q25 risk variants cause alterations in the intracellular calcium homoeostasis that predispose to spontaneous electrical activity.

METHODS AND RESULTS

Western blotting, confocal calcium imaging, and patch-clamp techniques were used to identify mechanisms linking the 4q25 risk variants rs2200733T and rs13143308T to defects in the calcium homoeostasis in human atrial myocytes. Our findings revealed that the rs13143308T variant was more frequent in patients with AF and that myocytes from carriers of this variant had a significantly higher density of calcium sparks (14.1 ± 4.5 vs. 3.1 ± 1.3 events/min, P = 0.02), frequency of transient inward currents (ITI) (1.33 ± 0.24 vs. 0.26 ± 0.09 events/min, P < 0.001) and incidence of spontaneous membrane depolarizations (1.22 ± 0.26 vs. 0.56 ± 0.17 events/min, P = 0.001) than myocytes from patients with the normal rs13143308G variant. These alterations were linked to higher sarcoplasmic reticulum calcium loading (10.2 ± 1.4 vs. 7.3 ± 0.5 amol/pF, P = 0.01), SERCA2 expression (1.37 ± 0.13 fold, P = 0.03), and RyR2 phosphorylation at ser2808 (0.67 ± 0.08 vs. 0.47 ± 0.03, P = 0.01) but not at ser2814 (0.28 ± 0.14 vs. 0.31 ± 0.14, P = 0.61) in patients carrying the rs13143308T risk variant. Furthermore, the presence of a risk variant or AF independently increased the ITI frequency and the increase in the ITI frequency observed in carriers of the risk variants was exacerbated in those with AF. By contrast, the presence of a risk variant did not affect the amplitude or properties of the L-type calcium current in patients with or without AF.

CONCLUSIONS

Here, we identify the 4q25 variant rs13143308T as a genetic risk marker for AF, specifically associated with excessive calcium release and spontaneous electrical activity linked to increased SERCA2 expression and RyR2 phosphorylation.

P1598Electrophysiological and structural characterization of acute atrial myocardial infarction

Background

Atrial myocardial infarction may be a risk for atrial fibrillation. However, the electrophysiological and structural characteristics of the infarcted atrial myocardium are not well known. This study aimed to analyse the changes in local atrial electrograms and myocardial structure in an experimental model of isolated atrial myocardial infarction.

Methods

Five anesthetized, open-chest pigs were submitted to 4 hours of acute atrial myocardial ischemia induced by direct surgical clamping of atrial coronary branches originating from the right coronary artery. In all cases, we recorded simultaneously the 12-lead surface electrocardiogram (ECG) and the epicardial mapping of local atrial electrograms (17 x 12.5 mm patches containing 128 electrodes, with 1 mm inter-electrode distance) in a region close to the occluded branches and in control non-treated atria. The changes in local atrial QRS-ST segment and the amplitude of the P-wave of the ECG were sequentially analysed (Figure). The hearts were removed and processed for anatomopathological examination.

Results

Selective atrial coronary branch occlusion induced a patchy atrial myocardial necrosis with an irregular and abrupt border zone (circled areas in the Figure). During the first 15 min of ischemia, the local atrial electrograms showed increasing R waves, widening of QRS complex, and ST segment elevation leading to monophasic potentials (maximal ST segment at 30 min: from 0.2±0.7 mV to 1.9±1.4 mV, ANOVA p<0.01). This period was followed by a phase of transient electrical recovery characterized by disappearance of monophasic potentials, reduction of ST segment elevation, and recovery of local electrical activation. After 60 min of occlusion, monophasic potentials reappeared and the magnitude of ST segment elevation decreased progressively during the ensuing 3 hours. The spatial transition from areas with monophasic potentials to normal electrograms encompassed 1 or 2 electrodes. The surface ECG showed increased duration of the P-wave (lead II at 3h occlusion: from 73.2±4.5 ms to 88.9±15.5 ms, ANOVA p<0.05) with absence of ST segment changes. Atrial arrhythmias were not observed.

Structural and electrical atrial changes

Conclusion

Selective occlusion of atrial coronary branches induced patchy atrial myocardial necrosis with abrupt anatomical and electrical border zone. The overt QRS and ST segment changes in local atrial electrograms resembled those described in acute ventricular myocardial ischemia, and were associated with widening of the P-wave on the surface ECG. Although acute ischemic arrhythmias were not observed, the atrial structural alterations might set the substrate for re-entrant arrhythmias late after the healing over process.

Acknowledgement/Funding

Supported by grants from ISCI-MINECO (FISPI17/00069), CIBERCV (CB16/11/00276), FEDER and Fundaciό “La Maratό” TV3 (20150830).

P3830Carvedilol treatment diminishes spontaneous calcium release and electrical activity in human atrial myocytes

Background

Atrial fibrillation (AF) has been associated with an increase in spontaneous calcium release induced electrical activity, which could potentially be reversed by carvedilol, a nonselective beta-blocker that also inhibits the cardiac ryanodine receptor (RyR2). Interestingly the enantiomer R-carvedilol inhibits the RyR2 but not beta-adrenergic receptors, allowing it to effectively prevent calcium release-induced spontaneous electrical activity without inducing bradycardia and hypotension.

Purpose

The purpose of this study was to determine how carvedilol treatment affects calcium release-induced transient inward currents (ITI) in human atrial myocytes from patients with AF; and to test the effects of R-carvedilol on spontaneous calcium release in order to assess its therapeutical utility.

Methods

Human atrial myocytes were isolated from patients undergoing cardiac surgery and subjected to patch-clamp technique (n=60) or confocal calcium imaging (n=6). Beta-2 adrenergic receptors were activated with the selective agonist fenoterol (3μM) and 1μM R-carvedilol was used to inhibit spontaneous calcium release events.

Results

Recordings of calcium release-induced transient inward currents (ITI) revealed that carvedilol treatment reduced the ITI frequency in patients with AF from 2.2±0.4 events/min in untreated patients to 0.59±0.35 events/min (p<0.01), which was even lower than the incidence in patients without AF (1.0±0.1 events/min; p<0.01). To assess the effects of R-carvedilol, myocytes were first simulated with fenoterol. This increased the calcium spark frequency from 23±15 to 960±336 events/s/1000μm2 in 16 cells from 6 patients (p<0.05). This was due to an increase in the spark site density (from 0.50±0.24 to 12.1±2.4 sites/1000μm2, p<0.001) rather than in the firing rate (0.068±0.14 vs. 0.035±0.012 sparks/s in control, p=0.14). Fenoterol also increased the spark duration from 50.9±5.4 to 77.3±4.1ms (p<0.001) without affecting the amplitude. Importantly, fenoterol also induced global calcium release events such as calcium waves and transients (2.8±1.1 vs. 0 events/min in control, p<0.05). When R-carvedilol was added, the effects of fenoterol were abolished, reducing the incidence of calcium sparks to 69±51 events/s/1000μm2 (p<0.05), the spark site density to 1.68±1.04 sites/1000μm2 (p<0.01), the spark duration to 63.4±4.3ms (p<0.05), and calcium waves and transients were reduced to 0.21±0.14 events/min (p<0.05).

Conclusions

Carvedilol treatment reduces the ITI frequency in patients with AF to levels below that observed at baseline in patients without AF. Furthermore, the non-beta-blocking R-carvedilol enantiomer abolishes spontaneous calcium release events induced by beta-2 adrenergic stimulation in human atrial myocytes, proposing a therapeutical utility for this compound in patients with AF linked to excessive spontaneous calcium release.

Acknowledgement/Funding

SAF2017-88019; Marato2015-20-30; SGR2017-1769; CIBERCV

P4535Discharge treatment with ACE inhibitor/ARB after a heart failure hospitalization is associated with a better prognosis irrespectively of left ventricular ejection fraction

Background

Medical therapy could improve the prognosis of real-life patients discharged after a heart failure (HF) hospitalization.

Purpose

We aimed to determine the impact of discharge HF treatment on mortality and readmissions in different left ventricular ejection fraction (LVEF) groups.

Methods

Multicentre prospective registry in 20 Spanish hospitals. Patients were enrolled after a HF hospitalization.

Results

A total of 1831 patients were included (583 [31.8%] HF with reduced ejection fraction [HFrEF]; 227 [12.4%] HF with midrange ejection fraction [HFmrEF]; 610 [33.3%] HF with preserved ejection fraction [HFpEF], and 411 [22.4%] with unknown LVEF. Angiotensin-converting enzyme (ACE) inhibitors/Angiotensin II receptor blockers (ARB) at discharge were independently associated with a reduction in: i) all-cause mortality: hazard ratio (HR) 0.55, 95% confidence interval (CI) 0.41–0.74, P<0.001, with a similar effect in the four groups; ii) mortality due to refractory HF HR 0.45, 95% CI 0.29–0.64, P<0.001, with a similar effect in the three groups with known LVEF; iii) mortality/HF admissions (HR 0.61; 95% CI: 0.50–0.74), more evident in HFrEF (HR 0.54; 95% CI: 0.38–0.78) compared to HRmEF (HR 0.64; 95% CI 0.40–1.02), orHFpEF (HR 0.70; 95% CI 0.53–0.92).Inpatients with HFrEFtriple therapy (ACE inhibitor/ARB+ betablocker+ mineralocorticoid receptor antagonist) was associated with the lowest mortality risk (HR 0.21; 95% CI: 0.08–0.57, P=0.002) compared to patients that received none of these drugs.

Events according to the number of drugs – HFrEF (n=583) 0 (n=14) 1 (n=98) 2 (n=160) 3 (n=294) P Death or heart failure readmissions 10 (71.4) 58 (59.2) 66 (41.3) 106 (36.1) <0.001 All-cause mortality 9 (64.3) 28 (28.6) 31 (19.4) 36 (12.2) <0.001 Mortality due to refractory heart failure 7 (50.0) 14 (14.3) 17 (10.6) 17 (5.8) <0.001 – HFmrEF (n=227) 0 (n=18) 1 (n=57) 2 (n=81) 3 (n=65) P Death or heart failure readmissions 9 (50.0) 35 (61.4) 34 (42.0) 25 (38.5) 0.057 All-cause mortality 5 (27.8) 18 (31.6) 15 (18.5) 11 (16.9) 0.191 Mortality due to refractory heart failure 3 (16.7) 7 (12.3) 7 (8.6) 4 (6.2) 0.475 – HFpEF (n=610) 0 (n=61) 1 (n=242) 2 (n=219) 3 (n=69) P Death or heart failure readmissions 32 (52.5) 97 (40.1) 89 (40.6) 20 (29.0) 0.057 All-cause mortality 20 (32.8) 41 (16.9) 32 (14.6) 10 (14.5) 0.017 Mortality due to refractory heart failure 11 (18.0) 18 (7.4) 13 (5.9) 4 (5.8) 0.041 Outcomes according to the number of medications at discharge.

Kaplan-Meier Curves for study outcomes

Conclusions

Discharge treatment with ACE inhibitor/ARB after a HF hospitalization is associated with a reduction in all-cause and refractory HF mortality, irrespectively of LVEF.

P1233Differential effects of five risk variants for atrial fibrillation at the 4q25 region on L-type calcium current and transient inward currents in human atrial myocytes

Background

An increasing number of single nucleotide polymorphisms (SNPs) at the chromosomal region 4q25 have been associated with risk of atrial fibrillation (AF) and we have recently reported that carriers of the rs13143308 risk variant have an increased incidence of spontaneous calcium release-induce transient inward currents (ITI). However, it is not known if different 4q25 variants have similar effects.

Purpose

This study aimed to compare the effects of five SNPs at 4q25 on L-type calcium current (ICa) and ITI frequency, features that are altered in patients with AF.

Methods

To avoid confounding effects of AF on calcium homeostasis, atrial samples from 63 patients without AF were genotyped and divided into groups according to the genotype of the SNPs rs1448818, rs6817105, rs13143308, rs6843082, rs3853443 ordered according to their location and identified by the three last digits + an R for risk or N for normal variants. ICa density and ITI frequency were measured with perforated patch clamp technique in atrial myocytes from these patients.

Results

Three SNPs 818, 308 and 443 segregated independently of the genotype at the other loci. The 105 and 082 loci always co-segregated with 308 but never together. The ICa density was smaller in carriers of 818R and 443N variants (−1.6±0.3pA/pF, p=0.01) or 818N and 443R variants (−1.6±0.4pA/pF, p=0.02) than in patients with 818N and 443N variants (−3.2±0.4pA/pF), independently of the genotype at 105, 308 and 082 (these loci did not affect ICa). In contrast, to this, the ITI frequency was increased only in myocytes from patients carrying 105R, 308R and 082N (1.4±0.2events/min, p<0.001) or 105N, 308R and 082R (1.6±0.5events/min, p=0.002) when compared to patients with 105N, 308N and 082N (0.36±0.09events/min) independently of the genotypes at 818 and 443, or when compared to patients without risk at any of the five loci (0.55±0.30events/min). The table shows schematically the qualitative effects of the different risk variants.

Risk variant rs1448818C rs6817105C rs13143308T rs6843082T rs3853445C ICa Decreased Unchanged Unchanged Unchanged Decreased ITI Unchanged Increased Increased Increased Unchanged

Conclusion

Different SNPs at the chromosomal region 4q25 are associated with differential pathological changes in intracellular calcium homeostasis. Risk variants at rs1448818 or rs3853445 cause loss of ICa without affecting ITI frequency while a risk variant at rs13143308 elevates the ITI frequency without affecting ICa. These findings afford a framework for stratification of pharmacological therapy based on the functional effects of the 4q25 risk variants

Acknowledgement/Funding

SAF2017-88019; Marato2015-20-30; SGR2017-1769; CIBERCV

P6361Prognostic value of discharge heart rate in acute heart failure patients: more relevant in atrial fibrillation?

Background

The prognostic impact of heart rate (HR) in acute heart failure (AHF) patients is not well known especially in atrial fibrillation (AF) patients.

Purpose

The aim of the study was to evaluate the impact of admission HR, discharge HR, HR difference (HRD) (admission- discharge) in AHF patients with sinus rhythm (SR) or AF on long- term outcomes.

Methods

We included 1398 patients consecutively admitted with AHF between October 2013 and December 2014 from a national multicentric, prospective registry. Logistic regression models were used to estimate the association between admission HR, discharge HR and HR difference and one- year all-cause mortality and HF readmission.

Results

The mean age of the study population was 72±12 years. Of these, 594 (42.4%) were female, 655 (77.8%) were hypertensive and 655 (46.8%) had diabetes. Among all included patients, 745 (53.2%) had sinus rhythm and 653 (46.7%) had atrial fibrillation. Only discharge HR was associated with one-year all-cause mortality (Relative risk (RR)= 1.182, confidence interval (CI) 95% 1.024–1.366, p=0.022) in SR. In AF patients discharge HR was associated with one-year all-cause mortality (RR= 1.276, CI 95% 1.115–1.459, p≤0.001). We did not observe a prognostic effect of admission HR or HRD on long-term outcomes in both groups. This relationship is not dependent on left ventricular ejection fraction (Figure 1)

Effect of post-discharge heart rate

Conclusions

In AHF patients lower discharge HR, neither the admission nor the difference, is associated with better long-term outcomes especially in AF patients

Acknowledgement/Funding

Heart Failure Program of the Red de Investigaciόn Cardiovascular del Instituto de Salud Carlos III, Madrid, Spain (RD12/0042) and the Fondo Europeo de

Comparison between endocardial and epicardial cardiac resynchronization in an experimental model of non-ischaemic cardiomyopathy

Aims

Pacing from the left ventricular (LV) endocardium might increase the likelihood of response to cardiac resynchronization therapy. However, experimental and clinical data supporting this assumption are limited and controversial. The aim of this study was to compare the acute response of biventricular pacing from the LV epicardium and endocardium in a swine non-ischaemic cardiomyopathy (NICM) model of dyssynchrony.

Methods and results

A NICM was induced in six swine by 3 weeks of rapid ventricular pacing. Biventricular stimulation was performed from 16 paired locations in the LV (8 epicardial and 8 endocardial) with two different atrioventricular (80 and 110 ms) intervals and three interventricular (0, +30, -30 ms) delays. The acute response of the aortic blood flow, LV and right ventricular (RV) pressures, LVdP/dtmax and LVdP/dtmin and QRS complex width and QT duration induced by biventricular stimulation were analysed. The haemodynamic and electrical beneficial responses to either LV endocardial or epicardial biventricular pacing were similar (ΔLVdP/dtmax: +7.8 ± 2.2% ENDO vs. +7.3 ± 1.5% EPI, and ΔQRS width: -16.8 ± 1.3% ENDO vs. -17.1 ± 1.9% EPI; P = ns). Pacing from LV basal regions either from the epicardium or endocardium produced better haemodynamic responses as compared with mid or apical LV regions (P < 0.05). The LV regions producing the maximum QRS complex shortening did not correspond to those inducing the best haemodynamic responses (EPI: r2 = 0.013, P = ns; ENDO: r2 = 0.002, P = ns).

Conclusion

Endocardial LV pacing induced similar haemodynamic changes than pacing from the epicardium. The response to endocardial LV pacing is region dependent as observed in epicardial pacing.

Electrocardiographic Distinction of Left Circumflexand Right Coronary Artery Occlusion in PatientsWith Inferior Acute Myocardial Infarction

Previously reported electrocardiographic (ECG) criteria to distinguish left circumflex (LCCA) and right coronary artery (RCA) occlusion in patients with acute inferior ST-segment elevation myocardial infarction (STEMI) afford a modest diagnostic accuracy. We aimed to develop a new algorithm overcoming limitations of previous studies. Clinical, ECG, and coronary angiographic data were analyzed in 230 nonselected patients with acute inferior STEMI who underwent primary percutaneous coronary intervention. A decision-tree analysis was used to develop a new ECG algorithm. The diagnostic accuracy of reported ECG criteria was reviewed. LCCA occlusion occurred in 111 cases and RCA in 119. We developed a 3-step algorithm that identified LCCA and RCA occlusion with a sensitivity of 77%, specificity of 86%, accuracy of 82%, and Youden index of 0.63. The area under the ROC curve was 0.85 and resulted 0.82 after a 10-fold cross validation. The key leads for LCCA occlusion were V3 (ST depression in V3/ST elevation in III >1.2) and V6 (ST elevation ≥0.1 mV or greater than III). The key leads for RCA occlusion were I and aVL (ST depression ≥ 0.1 mV). Fifteen of 21 reviewed studies had less than 20 cases of LCCA occlusion, only 48% performed primary percutaneous coronary intervention, and previous infarction or multivessel disease were often excluded. The diagnostic accuracy of reported ECG criteria decreased when applied to our study population. In conclusion, we report a simple and highly discriminative 3-step ECG algorithm to differentiate LCCA and RCA occlusion in an "all comers" population of patients with acute inferior STEMI. The diagnostic key ECG leads were V3 and V6 for LCCA and I and aVL for RCA occlusion.

Influence of Left Bundle Branch Block on the Electrocardiographic Changes Induced by Acute Coronary Artery Occlusion of Distinct Location and Duration

Background: Electrocardiographic (ECG) diagnosis of acute myocardial ischemia is hampered in the presence of left bundle branch block (LBBB).

Objectives: We analyzed the influence of location and duration of myocardial ischemia on the ECG changes in pigs with LBBB.

Methods: LBBB was acutely induced in 14 closed chest anesthetized pigs by local electrical ablation. Thereafter, episodes of 5 min catheter balloon occlusion followed by 10 min reperfusion of the left anterior descending (LAD), left circumflex (LCX), and right (RCA) coronary arteries were done sequentially in 5 pigs. Additionally, a 3-h occlusion of these arteries was performed separately in the other 9 pigs. A 15-lead ECG including leads V7 to V9 was continuously recorded.

Results: Ablation induced LBBB showed QRS widening, loss of r wave in V1, and predominant R waves in V2 to V9. After 5 min of ischemia the occluded artery could be identified in all cases: the LAD by R waves and ST elevation in V1–V3; the LCX by both ST segment elevation in II, III, aVF, V7 to V9 and ST segment depression in V1 to V4; and the RCA by ST depression and new S-waves in all precordial leads. Three hours after coronary occlusion, ST segment changes declined progressively and only the LAD occlusion could be reliably recognized.

Conclusion: LBBB did not mask the ECG recognition of the occluded coronary artery during the first 60 min of ischemia, but 3 h later only the LAD occlusion could be reliably identified. ST elevation in leads V7 to V9 is specific of LCX occlusion and it could be useful in the diagnosis of acute myocardial ischemia in the presence of LBBB.

Identification of new biophysical markers for pathological ventricular remodelling in tachycardia-induced dilated cardiomyopathy

Our aim was to identify biophysical biomarkers of ventricular remodelling in tachycardia-induced dilated cardiomyopathy (DCM). Our study includes healthy controls (N = 7) and DCM pigs (N = 10). Molecular analysis showed global myocardial metabolic abnormalities, some of them related to myocardial hibernation in failing hearts, supporting the translationality of our model to study cardiac remodelling in dilated cardiomyopathy. Histological analysis showed unorganized and agglomerated collagen accumulation in the dilated ventricles and a higher percentage of fibrosis in the right (RV) than in the left (LV) ventricle (P = .016). The Fourier Transform Infrared Spectroscopy (FTIR) 1st and 2nd indicators, which are markers of the myofiber/collagen ratio, were reduced in dilated hearts, with the 1st indicator reduced by 45% and 53% in the RV and LV, respectively, and the 2nd indicator reduced by 25% in the RV. The 3rd FTIR indicator, a marker of the carbohydrate/lipid ratio, was up-regulated in the right and left dilated ventricles but to a greater extent in the RV (2.60-fold vs 1.61-fold, P = .049). Differential scanning calorimetry (DSC) showed a depression of the freezable water melting point in DCM ventricles - indicating structural changes in the tissue architecture - and lower protein stability. Our results suggest that the 1st, 2nd and 3rd FTIR indicators are useful markers of cardiac remodelling. Moreover, the 2nd and 3rd FITR indicators, which are altered to a greater extent in the right ventricle, are associated with greater fibrosis.

Influence of sex and pregnancy on survival in patients admitted with heart failure: Data from a prospective multicenter registry

BACKGROUND

Female sex is an independent predictor of better survival in patients with heart failure (HF), but the mechanism of this association is unknown. On the other hand, pregnancies have a strong influence on the cardiovascular system.

HYPOTHESIS

Sex and previous gestations might have a prognostic impact on 1-year mortality in patients admitted with HF.

METHODS

We conducted an observational, prospective, consecutive, multicenter registry of 1831 patients (756 females [41.2%]) admitted with HF.

RESULTS

Females had a more advanced age (75.2 ±11.4 vs 70.4 ±12.2 years), less ischemic heart disease (167 [25.3%] vs 446 [47.3%]), and higher left ventricular ejection fraction (52.0% ±16.6% vs 41.1% ±17.0%) than did men (all P values <0.001). During 1-year follow-up, 373 (20.4%) patients died (151 females and 222 males). Female sex was an independent predictor for survival (hazard ratio: 0.79, 95% confidence interval: 0.64-0.98, P = 0.03). In 504 women (65.9%), the exact number of previous pregnancies could be determined; 62 women (12.3%) had no previous pregnancies, 288 (57.1%) women had 1 or 2 pregnancies, and 154 women (30.6%) had ≥3 pregnancies. We found an association between the number of previous gestations and better survival (hazard ratio: 0.878, 95% confidence interval: 0.773-0.997, P = 0.045).

CONCLUSIONS

In patients admitted with HF, female sex and the number of previous pregnancies are independently associated with better 1-year survival.

Summation and Cancellation Effects on QRS and ST-Segment Changes Induced by Simultaneous Regional Myocardial Ischemia

Simultaneous ischemia in two myocardial regions is a potentially lethal clinical condition often unrecognized whose corresponding electrocardiographic (ECG) patterns have not yet been characterized. Thus, this study aimed to determine the QRS complex and ST-segment changes induced by concurrent ischemia in different myocardial regions elicited by combined double occlusion of the three main coronary arteries. For this purpose, 12 swine were randomized to combination of 5-min single and double coronary artery occlusion: Group 1: left Circumflex (LCX) and right (RCA) coronary arteries (n = 4); Group 2: left anterior descending artery (LAD) and LCX (n = 4) and; Group 3: LAD and RCA (n = 4). QRS duration and ST-segment displacement were measured in 15-lead ECG. As compared with single occlusion, double LCX+RCA blockade induced significant QRS widening of about 40 ms in nearly all ECG leads and magnification of the ST-segment depression in leads V1-V3 (maximal 228% in lead V3, p < 0.05). In contrast, LAD+LCX or LAD+RCA did not induce significant QRS widening and markedly attenuated the ST-segment elevation in precordial leads (maximal attenuation of 60% in lead V3 in LAD+LCX and 86% in lead V5 in LAD+RCA, p < 0.05). ST-segment elevation in leads V7-V9 was a specific sign of single LCX occlusion. In conclusion, concurrent infero-lateral ischemia was associated with a marked summation effect of the ECG changes previously elicited by each single ischemic region. By contrast, a cancellation effect on ST-segment changes with no QRS widening was observed when the left anterior descending artery was involved.

Prevalence and incidence of hyperkalaemia in the Spanish population with heart failure with reduced ejection fraction: a systematic review and populational relevance

BACKGROUND AND OBJECTIVES

Hyperkalaemia (K⁺ levels≥5.5mmol/L) is a severe ion imbalance that occurs in patients who have heart failure (HF) with reduced ejection fraction (HFrEF) and increases the risk of ventricular fibrillation. Given that there are no estimates on the number of patients with this complication, the aim of this study was to estimate the prevalence and incidence of hyperkalaemia in patients with HFrEF in Spain.

MATERIAL AND METHODS

Based on a systematic literature search and through a meta-analysis, we calculated an HFrEF prevalence of ≤40% in the European and U.S.

POPULATION

Based on another systematic literature search, we calculated the prevalence of hyperkalaemia in patients with HF and its annual incidence rate. Considering the previous values and the Spanish population pyramid in 2016, we estimated the number of individuals with HFrEF who currently have hyperkalaemia and those who develop it each year in Spain.

RESULTS

Approximately 17,100 (10,000 men and 7100 women) of the 508,000 patients with HFrEF in Spain have hyperkalaemia. Furthermore, approximately 14,900 patients with HFrEF (9500 men and 5400 women) develop hyperkalaemia each year.

CONCLUSIONS

Approximately 1 of every 30 patients with HFrEF has plasma potassium values >5.5 mmol/L.

Myocardium of patients with dilated cardiomyopathy presents altered expression of genes involved in thyroid hormone biosynthesis

Background

The association between dilated cardiomyopathy (DCM) and low thyroid hormone (TH) levels has been previously described. In these patients abnormal thyroid function is significantly related to impaired left ventricular (LV) function and increased risk of death. Although TH was originally thought to be produced exclusively by the thyroid gland, we recently reported TH biosynthesis in the human ischemic heart.

Objectives

Based on these findings, we evaluated whether the genes required for TH production are also altered in patients with DCM.

Methods

Twenty-three LV tissue samples were obtained from patients with DCM (n = 13) undergoing heart transplantation and control donors (n = 10), and used for RNA sequencing analysis. The number of LV DCM samples was increased to 23 to determine total T4 and T3 tissue levels by ELISA.

Results

We found that all components of TH biosynthesis are expressed in human dilated heart tissue. Expression of genes encoding thyroperoxidase (–2.57-fold, P < 0.05) and dual oxidase 2 (2.64-fold, P < 0.01), the main enzymatic system of TH production, was significantly altered in patients with DCM and significantly associated with LV remodeling parameters. Thyroxine (T4) cardiac tissue levels were significantly increased (P < 0.01), whilst triiodothyronine (T3) levels were significantly diminished (P < 0.05) in the patients.

Conclusions

Expression of TH biosynthesis machinery in the heart and total tissue levels of T4 and T3, are altered in patients with DCM. Given the relevance of TH in cardiac pathology, our results provide a basis for new gene-based therapeutic strategies for treating DCM.

Endocardial infarct scar recognition by myocardial electrical impedance is not influenced by changes in cardiac activation sequence

BACKGROUND

Measurement of myocardial electrical impedance can allow recognition of infarct scar and is theoretically not influenced by changes in cardiac activation sequence, but this is not known.

OBJECTIVES

The objectives of this study were to evaluate the ability of endocardial electrical impedance measurements to recognize areas of infarct scar and to assess the stability of the impedance data under changes in cardiac activation sequence.

METHODS

One-month-old myocardial infarction confirmed by cardiac magnetic resonance imaging was induced in 5 pigs submitted to coronary artery catheter balloon occlusion. Electroanatomic data and local electrical impedance (magnitude, phase angle, and amplitude of the systolic-diastolic impedance curve) were recorded at multiple endocardial sites in sinus rhythm and during right ventricular pacing. By merging the cardiac magnetic resonance and electroanatomic data, we classified each impedance measurement site either as healthy (bipolar amplitude ≥1.5 mV and maximum pixel intensity <40%) or scar (bipolar amplitude <1.5 mV and maximum pixel intensity ≥40%).

RESULTS

A total of 137 endocardial sites were studied. Compared to healthy tissue, areas of infarct scar showed 37.4% reduction in impedance magnitude (P < .001) and 21.5% decrease in phase angle (P < .001). The best predictive ability to detect infarct scar was achieved by the combination of the 4 impedance parameters (area under the receiver operating characteristic curve 0.96; 95% confidence interval 0.92-1.00). In contrast to voltage mapping, right ventricular pacing did not significantly modify the impedance data.

CONCLUSION

Endocardial catheter measurement of electrical impedance can identify infarct scar regions, and in contrast to voltage mapping, the impedance data are not affected by changes in cardiac activation sequence.

Intercalated disc in failing hearts from patients with dilated cardiomyopathy: Its role in the depressed left ventricular function

Alterations in myocardial structure and reduced cardiomyocyte adhesions have been previously described in dilated cardiomyopathy (DCM). We studied the transcriptome of cell adhesion molecules in these patients and their relationships with left ventricular (LV) function decay. We also visualized the intercalated disc (ID) structure and organization. The transcriptomic profile of 23 explanted LV samples was analyzed using RNA-sequencing (13 DCM, 10 control [CNT]), focusing on cell adhesion genes. Electron microscopy analysis to visualize ID structural differences and immunohistochemistry experiments of ID proteins was also performed. RT-qPCR and western blot experiments were carried out on ID components. We found 29 differentially expressed genes, most of all, constituents of the ID structure. We found that the expression of GJA3, DSP and CTNNA3 was directly associated with LV ejection fraction (r = 0.741, P = 0.004; r = 0.674, P = 0.011 and r = 0.565, P = 0.044, respectively), LV systolic (P = 0.003, P = 0.003, P = 0.028, respectively) and diastolic dimensions (P = 0.006, P = 0.001, P = 0.025, respectively). Electron microscopy micrographs showed a reduced ID convolution index and immunogold labeling of connexin 46 (GJA gene), desmoplakin (DSP gene) and catenin α-3 (CTNNA3 gene) proteins in DCM patients. Moreover, we observed that protein and mRNA levels analyzed by RT-qPCR of these ID components were diminished in DCM group. In conclusion, we report significant gene and protein expression changes and found that the ID components GJA3, DSP and CTNNA3 were highly related to LV function. Microscopic observations indicated that ID is structurally compromised in these patients. These findings give new data for understanding the ventricular depression that characterizes DCM, opening new therapeutic perspectives for these critically diseased patients.