Management of Arrhythmias in the Cardiovascular Intensive Care Unit

Arrhythmias in the cardiovascular intensive care unit (CVICU) can be difficult to manage because of the complex hemodynamic and respiratory states of critically ill patients. Treating physicians must be educated to prevent, diagnose, and treat a multitude of tachyarrhythmias and bradyarrhythmias. In this review article, the authors outline a pragmatic approach to patient assessment, arrhythmia diagnosis, and management of the most common arrhythmias seen in the CVICU.

The SGLT2 inhibitor ertugliflozin causes a switch of cardiac substrate utilization leading to reduced cardiac mTOR-signaling, unfolded protein response and apoptosis

Introduction

SGLT2 inhibitors reduce hospitalization for heart failure in patients with and without diabetes. The underlying mechanisms remain incompletely understood but might relate to the induction of a fasting like response with low blood glucose and insulin levels and increased ketone bodies. The study aimed to investigate underlying signaling pathways.

Methods and results

Cardiac hypertrophy was induced by transverse aortic constriction (TAC) surgery in 20-week-old C57Bl/6J mice. Mice were treated with the SGLT2 inhibitor ertugliflozin (225 mg/kg chow diet) or vehicle for a period of 10 weeks.

Ertugliflozin significantly improved left ventricular systolic and diastolic function (dp/dtmax: TAC ctrl.: 8900±3362 mmHg/s vs. TAC ertu.: 12051±1604 mmHg/s (p<0.001) and dp/dtmin: TAC ctrl.: −7653±2770 mmHg/s vs. TAC ertu.: −10199±2463 mmHg/s (p<0.01); by millar catheter with dobutamine stress) and reduced myocardial fibrosis (p=0.17) and hypertrophy (p=0.09). This was paralleled by the expected fasting like response with lower glucose and insulin levels (HOMA-IR p<0.05) and increased ketone body concentrations (p<0.05). As a consequence cardiac insulin signaling (AKT-phosphorylation at Thr(308), 0.39-fold (p<0.01)) was reduced by ertugliflozin with less insulin-dependent glucose transporter GLUT4 expression (0.64-fold (p<0.05)) while fatty acid transporter CD36 (2.12-fold (p<0.001)) and the ketone body catabolizing key enzyme beta-hydroxybutyrate dehydrogenase BDH-1 were increased (1.59-fold (p<0.01)) in addition to AMPK-signaling (AMPK-phosphorylation at Thr(172), 1.62-fold (p<0.01)). This led to downstream inhibition of the mTOR pathway with reduced phosphorylation of p70S6K, 4E-BP1 and ULK1 (p70S6K-phosphorylation at Thr(389) (0.57-fold (p<0.05)), 4E-BP1-phosphorylation at Ser(65) (0.74-fold (p<0.05)) and ULK1-phosphorylation at Ser(757) (0.56-fold (p<0.01))). MTOR signaling critically mediates cardiac hypertrophy, endoplasmic reticulum stress, unfolded protein response (UPR) and adverse cardiac remodeling. Consistently, we found ertugliflozin to reduce ATF6 (0.69-fold (p<0.05)) and elf2α-phosphorylation at Ser(51) (0.66-fold (p=0.0611)) as well as downstream signaling (ATF4 0.58-fold (p<0.01); CHOP 0.36-fold (p<0.001)). This let to reduced caspase 3 (0.74-fold (p<0.05)), collagen I (0.60-fold (p<0.01)) and IL-1β (0.46-fold (p<0.01)) expression indicating less apoptosis, fibrosis and left ventricular remodeling with consequential reduction of BNP expression (0.60-fold (p<0.001)) in response to SGLT2 inhibition.

Conclusion

The SGLT2 inhibitor ertugliflozin improves left ventricular function in a murine model of cardiac hypertrophy. Mechanistically, this was associated with a metabolic switch of cardiac substrate utilization with reduced cardiac insulin- and increased cardiac AMPK-signaling leading to reduced cardiac mTOR-signaling, unfolded protein response and apoptosis.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): MSD

Hemodynamic Profiles of Shock in Patients With COVID-19

Patients with serious COVID infections develop shock frequently. To characterize the hemodynamic profile of this cohort, 156 patients with COVID pneumonia and shock requiring vasopressors had interpretable echocardiography with measurement of ejection fraction (EF) by Simpson's rule and stroke volume (SV) by Doppler. RV systolic pressure (RVSP) was estimated from the tricuspid regurgitation peak velocity. Patients were divided into groups with low or preserved EF (EF_L or EF_P, cutoff ≤45%), and low or normal cardiac index (CI_L or CI_N, cutoff ≤2.2 L/min/m²). Mean age was 67 ± 12.0, EF 59.5 ± 12.9, and CI 2.40 ± 0.86. A minority of patients had depressed EF (EF_LCI_L, n = 15, EF_LCI_N, n = 8); of those with preserved EF, less than half had low CI (EF_PCI_L, n = 55, EF_PCI_N, n = 73). Overall hospital mortality was 73%. Mortality was highest in the EF_LCI_L group (87%), but the difference between groups was not significant (p = 0.68 by ANOVA). High PEEP correlated with low CI in the EF_PCI_L group (r = 0.44, p = 0.04). In conclusion, this study reports the prevalence of shock characterized by EF and CI in patients with COVID-19. COVID-induced shock had a cardiogenic profile (EF_LCI_L) in 9.6% of patients, reflecting the impact of COVID-19 on myocardial function. Low CI despite preservation of EF and the correlation with PEEP suggests underfilling of the LV in this subset; these patients might benefit from additional volume. Hemodynamic assessment of COVID patients with shock with definition of subgroups may allow therapy to be tailored to the underlying causes of the hemodynamic abnormalities.

A Fibromuscular Dysplasia Clinical Tetrad of Coronary Artery Dissection, Cardiogenic Shock, Carotid Dissection, and Stroke

Spontaneous coronary artery dissection is a serious and underreported clinical entity strongly associated with fibromuscular dysplasia (FMD). The female predominance of FMD may predispose many women to coronary artery dissection or other similar vascular pathologies. We present a case of a young woman who presented with a clinical tetrad of spontaneous coronary artery dissection, cardiogenic shock requiring extracorporeal membrane oxygenation, internal carotid dissections, and subacute cerebellar infarct secondary to underlying FMD. The patient's clinical course and vascular pathology are discussed. A review of the relevant literature of previously published similar cases, the incidence of spontaneous coronary artery dissection, and issues in the clinical management of spontaneous coronary artery dissection are also included.

Renin-angiotensin system blockade after transcatheter aortic valve replacement (TAVR) improves intermediate survival

Introduction: Hypertension is common in patients with severe aortic stenosis undertaking transcatheter aortic valve replacement (TAVR). Renin–angiotensin system (RAS) blockade therapy with angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) has recently been associated with improved outcomes after surgical aortic valve replacement and TAVR, but it is unknown if these findings apply to a more rural patient population.

Methods: A retrospective cohort study of 169 patients with at least 1 year of post-TAVR follow-up at a single predominantly rural US center was performed to determine if RAS blockade after TAVR affects short- and long-term outcomes. Seventy-one patients were on an ACEI or ARB at the time of TAVR and at 1 year post-TAVR follow-up. Fisher’s exact test was used for categorical data and t-test/ANOVA was used to determine the statistical significance of continuous variables.

Results: In a well-matched cohort, RAS blockade therapy post-TAVR was associated with significantly improved overall survival at 2 years (95% vs. 79%, P = 0.042). RAS blockade was also associated with a trend towards decreased heart failure exacerbations in the first year after TAVR, which was statistically significant in the 30 days to 6 months timeframe after TAVR (8% vs. 21%, P = 0.032).

Conclusion: In a rural patient population, RAS blockade after TAVR is associated with improved overall survival and a trend towards decreased heart failure exacerbations. This study builds upon previous studies and suggests that TAVR should be considered a compelling indication for these agents.

Is There an Association Between Heparin-Induced Thrombocytopenia (HIT) and Autoimmune Disease?

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is a drug-induced, immunoglobulin G medicated autoimmune disorder associated with several negative clinical outcomes including increased morbidity, mortality, and increased medical costs. Previous studies have shown associations between comorbid autoimmune diseases, but there is little known about associations between HIT and autoimmunity.

PURPOSE

To provide clinical data to suggest an association between HIT and autoimmunity.

METHODS

Retrospective chart review of 59 cases with a diagnosis of HIT and 251 matched controls without a HIT diagnosis, comparing the prevalence of autoimmunity in each group.

SETTING

A single, large upper Midwest health care system.

RESULTS

Patients with a diagnosis of HIT were significantly more likely to have a comorbid autoimmune disease than those without a HIT diagnosis (55.9% vs 10.8%, P < 0.001). In disease-specific analyses, patients with a diagnosis of HIT were significantly more likely to have a diagnosis of antiphospholipid syndrome (15.3% vs 0.0%, P < 0.001), systemic lupus erythematous (8.5% vs 0.4%, P = 0.001), rheumatoid arthritis (5.1% vs 0.0%, P = 0.007), Hashimoto's thyroiditis (13.6% vs 3.6%, P = 0.006), or nonischemic cardiomyopathy (5.1% vs 0.0%, P = 0.007). Patients diagnosed with HIT were significantly older than controls (P < 0.001).

CONCLUSION

This novel study gives evidence to suggest an association between HIT and autoimmune disease and suggests a need for more research into the relationship between HIT and autoimmunity. These results could alter the anticoagulation management of venous thromboembolism and acute coronary syndrome in patients with a previously identified autoimmune disease.

Transcatheter Aortic Valve Replacement After Coronary Artery Bypass Graft Is Associated With Increased Pacemaker Implantation but Not Reduced Overall Survival

Background

A history of coronary artery bypass graft (CABG) is a common compelling indication for transcatheter aortic valve replacement (TAVR). However, there is little data on how these patients compare to other TAVR patients. In this study, the short and long-term outcomes of these TAVR patients after CABG are defined.

Methods

A retrospective chart review case-control study of 337 consecutive patients who underwent a TAVR for severe aortic stenosis at Sanford Health in Fargo ND was performed to determine if a history of prior CABG was associated with worse outcomes after TAVR as compared to a TAVR cohort without a history of CABG.

Results

Despite higher predicted surgical risk, patients with a history of CABG had no significant difference overall survival at 1 month (98% vs. 93%, P = 0.112), 6 months (94% vs. 87%, P = 0.094), 1 year (85% vs. 77%, P = 0.206) or 2 years (70% vs. 57%, P = 0.135) post-TAVR. However, a history of CABG was associated with an increase in post-TAVR permanent pacemaker (PPM) implantation (15% vs. 6%, P = 0.015).

Conclusions

This study gives evidence to suggest that patients with a history of prior CABG do not have any difference in overall survival as other TAVR patients, despite higher predicted surgical risk and differences in preprocedural comorbidities. Our study also confirms the safety of TAVR in this specific population in lower volume centers.