Takotsubo syndrome-like model in rats with high reproducibility and low mortality

Background/Purpose

Takotsubo syndrome (TS) is an acute form of heart failure with similar mortality and clinical presentation as myocardial infarction. The pathophysiology of the potentially life-threatening syndrome is only partially understood. This experimental study aimed to produce a human-like TS model with high reproducibility and low mortality. Rats have been the small-animal model of choice for preclinical studies within the cardiovascular field, successfully translating gained knowledge to humans. A relevant animal model can aid in elucidating mechanisms behind TS and serve as a platform for developing evidence-based treatment guidelines specific for the disease, which are currently missing.

Methods

190 Sprague Dawley rats (male, ∼300 g, ∼47 d) were infused i.v. with a single dose of the β-adrenergic agonist isoprenaline. The first study group was randomized by infusion time (ranging from 1 min to 60 min) while maintaining a fixed total dose (6.25 mg/kg), and the second group by total dose (0.1–50 mg/kg) with specified infusion time. The studies were replicated with saline infusion as a control. This study looked at mortality, the incidence of apical akinesia, the extent of apical akinesia, and recovery time. ECG, HR, SpO2, and temperature were monitored during the induction phase (<60 min) and at time points for imaging. High-resolution speckle-tracking echocardiography was used to study heart function for up to 30 days. The study followed the principles of laboratory animal care and was approved by our institution's Animal Ethics Committee.

Results

Mechanical dyssynchrony preceded global contractile dysfunction and development of transient apical akinesia. LV function and contractility normalised after 1 to 7 days. All surviving rats showed normal behaviour, ECG, and imaging at 30 days. TS-like phenotype was achieved in 92.9% of survivors. Mortality at 30-day was 6.7%. The deceased animals developed complications like TS patients including heart failure, malignant arrhythmias, LV mural thrombus formation, cardiogenic shock. Longer infusion time was associated with increased mortality (p=0.002), but not with the incidence of akinesia (p=0.818). The extent of apical akinesia decreased at the shortest infusion time (1 min) while at 7.5 minutes and above, it did not differ. The replication study validated these findings, although variability in incidence and mortality was seen across the groups.

Conclusions

This study provides a highly reproducible TS-like model with low mortality and excellent translational potential. High-resolution imaging and the natural course demonstrated the presence of the most critical characteristics of TS-like phenotype as in humans. The model also validates other findings related to TS including variability in the susceptibility to develop TS-like phenotype and complications. Our model provides a solid experimental platform for future preclinical studies of TS.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): ALF - Swedish Research Council

Does the quality index of adherence to the evidence-based guidelines predict mortality in patients with myocardial infarction?

Background

The SWEDEHEART quality index of hospitals' adherence to the evidence-based (EB) guidelines for myocardial infarction (MI) patients has been continuously used for several decades in Sweden. The grading protocol is based on the consensus among hospitals. The hospitals are awarded points (0, 0.5, 1) for each of the 11 indicators depending on the proportion of patients who received EB treatment and achieved treatment goals. The 11 indicators at present are reperfusion treatment in STEMI (yes/no), time to-reperfusion treatment in STEMI, time to revascularisation in NSTEMI, P2Y12 antagonists at discharge, ACE-inhibitor/ARB at discharge, the proportion of patients at follow-up, smoking cessation at one-year, participation in a physical exercise program, target LDL-cholesterol and target blood pressure at one year.

Purpose

To evaluate whether the SWEDEHEART quality index predicts mortality in patients with MI.

Methods

We used data for all MI patients reported to the SWEDEHEART registry from 72 hospitals in Sweden between 2015–2021. We calculated the difference in quality index between 2021 and 2015. The hospitals were divided into quintiles based on the difference in the score. Logistic regression with log-time offset was used to adjust for confounders (age, gender, diabetes, hypertension, hyperlipidemia, STEMI/NSTEMI, cardiac arrest before admission, occupation status, history of heart failure, prior MI, prior PCI, prior CABG, cardiogenic shock).

Results

We identified 98,635 patients with MI, 32,608 (33.1%) were women and 34,198 (34.7%) had STEMI. The average age was 70.8±12.2 years. The median follow-up time was 2.7 years (IQR 1.06–4.63). The crude all-cause mortality rate was 5.5% at 30-days and 22.3% after long-term follow-up. Most hospitals (72.1%) improved their quality index on average by 3.4% per year (P<0.001). The increase in the quality index continued during COVID-19 pandemic (2020–2021) with average increase of 8.6%, 95% CI, 0.97–1.02; P<0.001. The median change in SWEDEHEART quality index score among the quintiles were −1.5 (Q1), 0,5 (Q2), 2,5 (Q3), 3 (Q4), and 4 (Q5). We found no difference in mortality between the quintiles at 30-days (OR 0.99; 95% CI 0.97–1.02; p=1.02) and long-term (OR 1.01; 95% CI 0,99–1.02; p=0.850).

Conclusion

The SWEDEHEART quality index provides valuable descriptive information about hospitals' adherence to the guidelines. However, the index, in its current form, does not predict mortality in patients with MI.

Funding Acknowledgement

Type of funding sources: None.

Early changes in myocardial stunning and biomarkers after ST-elevation myocardial infarction compared to the takotsubo syndrome

Background

Takotsubo syndrome (TS) and ST-elevation myocardial infarction (STEMI) are both characterized by sudden cessation of myocardial contractions (myocardial stunning) as well as elevation of cardiac troponins and B-type natriuretic peptides (BNP). Whereas STEMI results in variable degrees of necrosis and persistent cardiac dysfunction, TS results in little to any necrosis and full recovery of cardiac function. No “head-to-head” comparison of the temporal resolution of myocardial stunning and serum biomarkers in STEMI versus takotsubo has been done.

Purpose

To compare the time course of the recovery of cardiac function and serum biomarkers over the acute and subacute phases of takotsubo and STEMI, with patients with STEMI further subdivided into anterior and non-anterior STEMI.

Method

The Stunning In Takotsubo and Acute Myocardial Infarction (STAMI) study is a prospective, multi-center study that enrolls patients with TS or STEMI without known pre-existing cardiac dysfunction. Echocardiography, laboratory testing (including troponins and NT-proBNP), and ECG are acquired within 4 hours after acute coronary angiography and at 24±6, 48±12, 72±12 hours and 7±1, 14±2, and 30±2 days. The primary endpoint is the proportion of reversible myocardial akinesia resolved after 72 hours (Figure 1), as determined by echocardiography. Secondary endpoints include troponin-I, troponin-T, and NT-proBNP.

Results

Preliminary results from 155 patients with STEMI (78 anterior STEMI and 77 non-anterior STEMI) and 32 patients with TS are presented in Figure 1. Mean (SD) age was similar for patients with takotsubo (67±14), anterior STEMI (68±11), and non-anterior STEMI (68±10). All 3 groups showed substantial recovery of cardiac function over the course of the study, with the most pronounced recovery of cardiac function in TS. Compared to both STEMI groups, the TS group also had lower troponin-I to troponin-T ratio, and higher NT-proBNP (Figure 2). The proportion of reversible akinesia that had recovered at 72 hours was similar in patients with TS, anterior STEMI and non-anterior STEMI (p=0.8414).

Conclusion

The STAMI study will provide the comprehensive assessment of cardiac function and serum biomarker profile of patients with takotsubo and STEMI over the early course of the disease. Preliminary data from the study suggest that early myocardial functional recovery is more substantial but follows a similar time-course in takotsubo and STEMI. The differences in the magnitude of troponin elevation after takotsubo versus STEMI were more pronounced for troponin-I than T.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): ERC - European Research Council

Comparison between ticagrelor and clopidogrel in high bleeding risk patients with acute coronary syndrome

Background

Potent antiplatelet agents such as ticagrelor are associated with a lower risk of ischemic events than clopidogrel in patients with acute coronary syndrome (ACS). However, it is uncertain whether the benefits of more intensive anti-ischemic therapy outweigh the risks of major bleeding in individuals who have a high bleeding risk (HBR). This study aimed to assess treatment outcomes following dual antiplatelet therapy (DAPT) using either ticagrelor or clopidogrel in ACS patients with HBR.

Methods

All HBR patients enrolled in the SWEDEHEART registry who were discharged with DAPT using ticagrelor or clopidogrel following ACS between 2010 and 2017 were included in this study. Bleeding risk was assessed using the 4-item PRECISE-DAPT score, which consists of age, prior bleeding, haemoglobin concentration and creatinine clearance. HBR was defined as a PRECISE-DAPT score ≥25. Inverse-probability of treatment weighting was used to adjust for baseline differences between the treatment groups. The main analysis consisted of a doubly robust estimation of causal effect using Cox proportional hazards models. Data on major bleeding, recurrent myocardial infarction (MI), ischemic stroke and all-cause mortality was obtained from national registries, with 365 days of follow-up. Additional outcomes include major adverse cardiovascular events (MACE), a composite of MI, ischemic stroke and all-cause mortality, and net adverse clinical events (NACE), a composite of MACE and major bleeding.

Results

Of all ACS patients, 36% (n=25,042) had a PRECISE-DAPT score ≥25. Approximately half of the study participants were treated with ticagrelor (n=11,848). Ticagrelor reduced the risk of MI (hazard ratio [HR], 0.82 [95% CI 0.74–0.91]), ischemic stroke (HR, 0.73 [95% CI 0.60–0.88]) and MACE (HR, 0.90 [95% CI 0.84–0.97]), while also increasing the risk of major bleeding compared to clopidogrel (HR, 1.30 [95% CI 1.16–1.47]). We found no significant differences in all-cause mortality (HR 1.02 [95% CI 0.92–1.12]) and NACE (HR 0.98 [95% CI 0.92–1.05]).

Conclusions

Ticagrelor was associated with a lower risk of recurrent ischemic events, but a higher risk of major bleeding compared to clopidogrel. There were no significant differences in all-cause mortality and NACE between the treatment groups. These results suggest that more potent antiplatelet agents might not be superior to clopidogrel in ACS patients with HBR.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Stockholm county council

Poor long-term prognosis in patients admitted with strong suspicion of acute myocardial infarction but discharged with another diagnosis

BACKGROUND

Characteristics and prognosis of patients admitted with strong suspicion of myocardial infarction (MI) but discharged without an MI diagnosis are not well-described.

OBJECTIVES

To compare background characteristics and cardiovascular outcomes in patients discharged with or without MI diagnosis.

METHODS

The DETermination of the role of Oxygen in suspected Acute Myocardial Infarction (DETO2X-AMI) trial compared 6629 patients with strong suspicion of MI randomized to oxygen or ambient air. The main composite end-point of this subgroup analysis was the incidence of all-cause death, rehospitalization with MI, heart failure (HF) or stroke during a follow-up of 2.1 years (median; range: 1-3.7 years) irrespective of randomized treatment.

RESULTS

1619 (24%) received a non-MI discharge diagnosis, and 5010 patients (76%) were diagnosed with MI. Groups were similar in age, but non-MI patients were more commonly female and had more comorbidities. At thirty days, the incidence of the composite end-point was 2.8% (45 of 1619) in non-MI patients, compared to 5.0% (250 of 5010) in MI patients with lower incidences in all individual end-points. However, for the long-term follow-up, the incidence of the composite end-point increased in the non-MI patients to 17.7% (286 of 1619) as compared to 16.0% (804 of 5010) in MI patients, mainly driven by a higher incidence of all-cause death, stroke and HF.

CONCLUSIONS

Patients admitted with a strong suspicion of MI but discharged with another diagnosis had more favourable outcomes in the short-term perspective, but from one year onwards, cardiovascular outcomes and death deteriorated to a worse long-term prognosis.

The association of mode of location activity and mobility with acute coronary syndrome: a nationwide ecological study

BACKGROUND

We aimed to study the effect of social containment mandates on ACS presentation during COVID-19 pandemic using location activity and mobility data from mobile phone map services.

METHODS

We conducted a cross-sectional study using data from the Swedish Coronary Angiography and Angioplasty Registry (SCAAR) including all ACS presentations during the pandemic until 7 May 2020. Using a count regression model, we adjusted for day of the week, daily weather and incidence of COVID-19.

RESULTS

A 10% increase in activity around areas of residence was associated with 38% lower rates of ACS hospitalizations, whereas increased activity relating to retail and recreation, grocery stores and pharmacies, workplaces and mode of mobility was associated with 10-20% higher rates of ACS hospitalizations.

CONCLUSION

Government policy regarding social containment mandates has important public health implications for medical emergencies such as ACS and may explain the decline in ACS presentations observed during COVID-19 pandemic.

Comparative Effectiveness of CABG versus PCI in Patients with Ischemic Heart Disease: insights from SWEDEHEART Registry

Background

Several studies have compared CABG to PCI as revascularization treatment in patients with ischemic heart disease (IHD). However, it remains unclear which revascularization strategy carries survival benefits in the long-term.

Methods

We used data from the SWEDEHEART (Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies) registry for all hospital admissions at 13 cardiac care centers within Västra Götaland County in Sweden (∼20% of all SWEDEHEART data). The database contains &gt;1000 clinical variables documenting the entire process of acute coronary hospital care. All patients hospitalized for stable angina or NSTE-ACS during the period 2000–2018 were included in the analysis. We used a propensity score-adjusted Cox proportional-hazards regression with hospitals as random-effect variables. We adjusted for patients' demographics, socio-economic status, traditional risk factors, comorbidities, the severity of coronary artery disease, left ventricular function, calendar year and medication at discharge. For sensitivity analysis, we used the instrumental variable estimator for the Cox proportional-hazards model (with treating hospital as a treatment-preference instrument) to simultaneously deal with the problems of unmeasured confounding and censoring of the outcome. The primary outcome was all-cause mortality.

Results

In total, 11,896 patients were included in the study. Of these, 3,129 (26.3%) were women. 20.4% had diabetes and 10.4% had a previous myocardial infarction. The mean age was 66.7±10.7, and 42.9% were &gt;70 years old. 61.5% had three-vessel and/or left main disease. Median follow-up time was 5.7 years (range 1 day-18.2 years). Revascularization therapy after coronary angiography was PCI in 9449 (79.4%) and CABG in 2,447 (20.6%) patients. CABG patients were more likely to have diabetes, left main/multivessel disease and heart failure. The number of revascularized patients with PCI increased by 6.4% per calendar year (P&lt;0.001). There were 2,481 (20.9%) deaths. CABG was associated with a lower risk of death compared to PCI (HR 0.81; 95% CI 0.69–0.95; P=0.011. We found no evidence for treatment heterogeneity between the revascularization strategy and age, gender, diabetes, heart failure and indication for revascularization (all P-interaction &gt;0.05). Results from the sensitivity analysis support the conclusions from the primary model.

Conclusions

In hospitalized patients due to IHD, revascularization with CABG was associated with superior long-term survival compared to PCI.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Heart and Lung Foundation, ALF Västra Götaland, Swedish Scientific Council

Long-term survival in patients with coronary artery disease undergoing percutaneous coronary intervention with or without intracoronary pressure wire guidance: a report from SCAAR

Background

Intracoronary pressure wire measurements of fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) provide decision-making guidance during percutaneous coronary intervention (PCI). However, limited data exist on the impact of FFR/iFR on long-term clinical outcomes in patients with stable angina, unstable angina (UA)/non-ST-segment elevation myocardial infarction (NSTEMI), or STEMI.

Methods

We used data from the Swedish Coronary Angiography and Angioplasty Registry (SCAAR) on all patients in Sweden undergoing PCI (with or without FFR/iFR guidance) for stable angina, UA/NSTEMI, or STEMI between January 2005 and March 2018. The primary endpoint was all-cause mortality and the secondary endpoints were stent thrombosis or restenosis and periprocedural complications. The primary model was multilevel Cox proportional-hazards regression using an instrumental variable (IV) to adjust for known and unknown confounders with treating hospital as a treatment-preference instrument. The following variables were entered into Cox proportional-hazards regression in addition to the IV: age, sex, diabetes, indication for PCI, severity of coronary disease, smoking status, hypertension, hyperlipidemia, previous myocardial infarction, previous PCI, previous coronary artery bypass graft, type of stent.

Results

In total, 151,001 patients underwent PCI: 31,514 (20.9%) for stable angina, 74,982 (49.6%) for UA/NSTEMI, and 44,505 (29.5%) for STEMI. Of these, FFR/iFR guidance was used in 11,433 patients (7.6%): 5029 (44.0%) with stable angina, 5989 (52.4%) with UA/NSTEMI, and 415 (3.6%) with STEMI; iFR was used in 1156 (10.1%) of these patients. After a median follow-up of 1784 (range 1–4824) days, the FFR/iFR group had lower adjusted risk estimates for all-cause mortality [hazard ratio (HR) 0.79; 95% confidence interval (CI) 0.69–0.91; P=0.001] and stent thrombosis and restenosis (HR 0.13; 95% CI 0.09–0.19; P&lt;0.001). The number of periprocedural complications did not differ significantly between the groups (odds ratio 0.69; 95% CI 0.30–1.55; P=0.368). There was no interaction between FFR/iFR and indication for PCI. We found no difference between FFR and iFR (HR 1.12; 95% CI 0.90–1.59; P=0.216).

Conclusions

In this observational study, the use of FFR/IFR was associated with a lower risk of long-term mortality in patients undergoing PCI for stable angina, UA/NSTEMI, or STEMI. Our study supports the current European and American guidelines for the use of FFR/iFR during PCI and shows that intracoronary pressure wire guidance has prognostic benefit in patients with stable angina as well as in patients with the acute coronary syndrome.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Heart and Lung Foundation, ALF Västra Götaland, Swedish Scientific Council

Uninterrupted oral anticoagulant therapy in patients undergoing unplanned percutaneous coronary intervention

Background

To investigate the optimal periprocedural antithrombotic strategy in patients on oral anticoagulants (OAC) who undergoing unplanned percutaneous coronary intervention (PCI).

Methods

Using data from the SWEDEHEART registry, we identified all patients on OAC who underwent an unplanned PCI, from 2005 to 2017. We compared uninterrupted OAC (U-OAC) vs interrupted OAC (I-OAC) therapy, defined as any discontinuation of OAC at least 24 hours prior to PCI. Outcomes were major adverse cardiac and cerebrovascular events (MACCE), including death, MI or stroke and net adverse cardiac and cerebrovascular events (NACCE), including MACCE or major bleeds, up to 120 days after the index procedure.

Results

We included 6485 patients, 3163 in U-OAC and 3322 in I-OAC group. The U-OAC strategy increased over time, by 13% per year. Almost 80% of patients in both groups had an acute coronary syndrome. We found no major differences in terms of medical history, clinical characteristics and the CRUSADE bleeding score on admission. The proportion of patients on warfarin was higher in the I-OAC group (85 vs 81%). Patients in the I-OAC were more likely to receive low-molecular weight heparin (29 vs 12%) and glycoprotein IIb/IIIa inhibitors (6 vs 3%) during the index hospitalisation. In the I-OAC group, dual antiplatelet therapy without OAC was more often prescribed (22 vs 8%) and OAC plus single antiplatelet therapy was less often prescribed (8 vs 22%) at discharge.

At 120 days, the cumulative rate of MACCE was 8.2 vs 8.2% and the rate of NACCE was 12.6 vs 12.9% in I-OAC vs U-OAC, respectively. We found no significant difference in the risk for MACCE and NACCE between the two groups (table). The risk for major or minor in-hospital bleeds was similar. I-OAC was associated with significantly longer time-delay to PCI and length of hospitalisation (table).

Conclusion

Uninterrupted OAC was safe and was associated with significantly shorter length of hospitalisation. Our data support U-OAC as the preferable strategy in patients on OAC undergoing PCI.

Funding Acknowledgement

Type of funding source: None

Utilization and outcomes of rotational atherectomy in Sweden

Aim

To evaluate utilization and outcomes of rotational atherectomy (RA) using data from the Swedish Coronary and Angioplasty Registry (SCAAR)

Methods

We included 1476 patients with 2218 lesions who underwent RA from 2005 to 2016. To study temporal changes, the study period was divided into three equal time-periods, period A, B and C.

Results

Although the number of RA procedures increased 3-fold from 2005 to 2016, the rate of RA (of all PCI procedures) remained low (0.5% vs 1.2% in 2005 vs 2016). RA patients consisted a high-risk group, with advanced age and clustering of comorbidities. Over time, included patients were older and had a higher risk profile. Trans-radial access, drug eluting stent (DES) use and use of intravascular imaging significantly increased from period A to C whereas positioning of a temporary pacemaker or intra-aortic balloon pump declined. Unfractionated heparin became the main anticoagulant (52 vs 87%) and use of glycoprotein IIb/IIIa inhibitors declined (31 vs 12%, in period A vs C). Following RA, 11% of lesions were treated without stent (15 vs 15 vs 8%, in period A, B and C) (Rota-only). In lesions treated with a stent, a bare metal stent (BMS) was implanted in 39% vs 12% vs 2% and a new generation DES (N-DES) in 5 vs 75 vs 97% (period A vs B vs C) of lesions.

The 3-year cumulative rate of restenosis was 6.7% (122 events), (11.1 vs 7.1 vs 4.1% in period A vs B vs C). As compared to DES, rota-only (adjusted HR 2.71; 95% CI 1.69- 4.36) and BMS (adjusted HR 3.63; 95% CI 2.27- 5.81) were associated with significantly higher risk for restenosis. First generation DES were associated with numerically higher but not significantly different risk for restenosis as compared to N-DES (adjusted HR 1.31; 95% CI 0.74- 2.31).

The 3 year cumulative rate of major adverse cardiac events (MACE), including death, myocardial infarction (MI) or any restenosis was 30.6% (34.2 vs 31.4 vs 28.2%, in period A vs B vs C) and the corresponding numbers for all-cause mortality were 18.1% (18.9 vs 18.4 vs 17.0%). After adjustment for baseline characteristics and angiographic findings, RA in period A was associated with higher risk for MACE as compared to period C (adjusted HR 1.40; 95% CI 1.09- 1.79), due to higher risk for MI and restenosis. The difference disappeared when procedural characteristics, including DES use, were added to the model.

The rate of major in-hospital complications was 7.0%, including in-hospital death 1.3%, periprocedural MI 2.8%, perforation 1.1%, cardiac tamponade 0.7%, stroke 0.2% and major bleedings 2.1%. We found no significant differences over time.

Conclusion

During the studied period, RA remained a rare procedure, utilised in a highly selected population. Over time a declining rate of restenosis and MI after RA was observed, a finding that appeared to be mainly driven by an increased use of DES. The rate of major in-hospital complication remained low.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Boston Scientific International

P1251Percutaneous coronary intervention versus medical therapy for coronary lesions with positive fractional flow reserve (FFR) but preserved coronary flow reserve (CFR). A substudy of the COMPARE-ACUTE

Introduction

International guidelines recommend performing percutaneous coronary intervention (PCI) on stable coronary lesions with a positive fractional flow reserve (FFR) to improve clinical outcomes. It remains unclear if FFR positive lesions with preserved coronary flow reserved (CFR) might be better treated medically.

Purpose

This study compared clinical outcomes between PCI and medical therapy for stable FFR-positive lesions with preserved CFR.

Methods

We performed a substudy of the randomized, multicenter COMPARE-ACUTE trial in which treated ST-elevation myocardial infarction patients with stable non-culprit lesions were randomized to either FFR-guided PCI or medical therapy. Based on baseline and hyperaemic pressure gradients, we computed the so-called pressure bounded-CFR (pb-CFR) and classified lesions as low (<2) or preserved (≥2). Our primary end point was a composite of death from any cause, non-fatal myocardial infarction, revascularization, or cerebrovascular events (MACCE) at 12 months.

Results

A total of 980 lesions from 885 subjects were included in this sub-study due to availability of baseline and hyperaemic pressure gradients. For the 462 lesions with FFR≤0.80, 249 had a pb-CFR<2 while 29 had a preserved CFR (pb-CFR≥2). The rate of MACCE at 1 year did not differ significantly between subjects with FFR≤0.80 and pb-CFR<2 versus FFR≤0.80 and pb-CFR≥2 (24% vs. 30%, p=0.44). Because of randomization, baseline characteristics were well balanced between subjects with FFR≤0.80 and pb-CFR≥2 who were treated by PCI or medical therapy. Importantly for subjects with FFR≤0.80 and pb-CFR≥2, MACCE occurred more frequently when treated medically compared with PCI (50% vs. 0% respectively, p=0.01).

Conclusions

In this post-hoc substudy from a large randomized controlled trial of 885 subjects with 980 lesions, a preserved pb-CFR≥2 did not associate with an improved clinical outcome when FFR≤0.80. Subjects with FFR-positive coronary lesions but a preserved pb-CFR experienced significantly worse clinical outcomes when treated medically instead of with PCI. These data suggest that a stenosis with a FFR≤0.80, even when pb-CFR remains preserved, benefits from treatment with PCI.

Acknowledgement/Funding

Maasstad Cardiovascular Research, Abbott Vascular and St. Jude Medical

467FFR guided acute complete revascularization versus culprit lesion only treatment in patients presenting with STEMI; 3-year cost-analysis data from COMPARE-ACUTE trial

Background

Compare-Acute trial showed a 1-year superior outcome of FFR-guided acute complete revascularization (FFR-CR) compared to culprit-lesion-only revascularization (CLO) in patients presenting with ST-segment elevation myocardial infarction (STEMI) and multi-vessel disease (MVD). Long-term results and financial impact of this strategy are unknown.

Purpose

To evaluate if FFR-CR strategy is superior to CLO strategy in terms of health care costs at 3 year follow-up.

Methods

Compare-Acute is a multicenter, investigator-initiated prospective randomized controlled trial that involved 24 sites. Patients with STEMI and MVD were randomized 1:2 after successful primary PCI, towards FFR-CR or CLO treatment strategies (295 vs 590 pts). All stenosis ≥50% by angiography in the non-infarct artery were investigated by FFR in both arms. In the FFR-CR arm, all non-culprit (NC) lesions with a FFR ≤0.80 were treated by PCI. In the CLO arm pts underwent blinded FFR procedure of the NC lesions. Further treatment of these lesions was based on symptoms and/or ischemia testing during follow-up with an allowed treatment window of 45 days. The primary endpoint was defined as a composite of all-cause mortality, non-fatal myocardial infarction, any revascularization and cerebrovascular events (MACCE) at 12 months. The major secondary endpoints are MACCE and health care costs from both strategies up to 3-year follow-up. Cost-analysis is done from an insurance/governmental perspective in countries that use Diagnosis Related Group (DRG) costs: the Netherlands, Germany, Sweden and Poland.

Results

1-year results have already been published and showed superior outcome of patients in the FFR-CR arm. According to the Dutch system, at 1 year of follow-up the average cost per patient was 8.150€ in the FFR-CR arm, and 10.319€ in the CLO arm (−21%). The better cost-effectiveness of FFR-CR strategy remained at 3 years of follow-up: average cost per patient was 8.653€ in the FFR-CR arm and 11.100€ in the CLO arm (−22%). Same 3-year data was confirmed using DRG analysis according to the German system (FFR-CR 4.887€ vs CLO 5.200€; −6.0%) and the Swedish system (FFR-CR 6.205€ vs CLO 8.133€; −23.7%). FFR-CR strategy was not more costly according to the Polish system (FFR-CR 3.704€ vs CLO 3.685€; +0.5%). Moreover, the better outcome of the FFR-CR group was mantained at 3 year follow-up (data not shown).

Figure 1

Conclusion

Our cost-analysis of the Compare Acute Trial shows that the strategy of FFR-guided complete revascularization in patients with STEMI and MVD is not only superior in terms of outcome, but also in terms of health care costs at 1 year. This benefit is maintained at 3 years follow-up.

1154FFR guided acute complete revascularization versus culprit lesion only treatment in patients presenting with STEMI and multi vessel disease; final 3-year outcome data from Compare-Acute trial

Background

Compare-Acute trial showed a 1-year superior outcome of FFR-guided acute complete revascularization (FFR-CR) compared to culprit-lesion-only revascularization (CLO) in patients presenting with ST-segment elevation myocardial infarction (STEMI) and multi-vessel disease (MVD). Long-term outcome results are unknown.

Purpose

To evaluate if FFR-CR strategy is superior to CLO strategy in terms of outcome at 3 year follow-up.

Methods

Compare-Acute is a multicenter, investigator-initiated prospective randomized controlled trial that involved 24 sites. Patients with STEMI and MVD were randomized, after successful primary PCI towards FFR-CR or CLO treatment strategies with a 1:2 ratio (295 pts vs 590 pts). All stenosis ≥50% in the non-infarct artery were investigated by FFR in both arms. In the FFR-CR arm, all non-culprit (NC) lesions with a FFR ≤0.80 were treated by PCI. In the CLO arm pts underwent blinded FFR procedure of the NC lesions. Further treatment of these lesions was based on symptoms and/or ischemia testing during follow-up with an allowed treatment window of 45 days. The primary endpoint was defined as a composite of all-cause mortality, non-fatal myocardial infarction, any revascularization and cerebrovascular events (MACCE) at 12 months. The major secondary endpoint is MACCE from both strategies up to 3-year follow-up.

Results

1-year clinical outcomes have already been presented and published. At 36 months the composite end-point of MACCE occurred in 46 patients in the FFR-CR group vs 178 patients in the CLO group (15.6% vs 30.2%; HR 0.46, 95% CI 0.29–0.59; p<0.01), as shown in Fig. 1. The incidence of death (4 pts vs 10 pts; 1.4% vs 1.7%; HR 0.86, 95% CI 0.39–1.8; p=0.71), MI (20 pts vs 53 pts; 7.1% vs 9.3%; HR 0.74, 95% CI 0.44–1.24; p=0.25) and stroke (1 pt vs 7 pts; 0.3% vs 1.2%; HR 0.29, 95% CI 0.03–2.3; p=0.24) was not significantly different in the two groups, but revascularizations were significantly higher in the CLO group: 37 patients in the FFR-CR group vs 149 patients in the CLO group (13.0% vs 26.0%; HR 0.45; 95% CI 0.31–0.64; p<0.01). Furthermore, in a subgroup analysis, when we considered only patients with FFR positive non-culprit lesions in both arms, we found a higher incidence of MI at follow-up in the CLO arm compared to the FFR-CR arm: 30/224 vs 13/194 (13.4% vs 6.7%; p 0.03).

MACCE-free survival at 3 years

Conclusion

With this analysis of the Compare-Acute trial we confirm that the benefit of a FFR-guided complete revascularization strategy in patients with STEMI and MVD is maintained at 3 years of follow-up. This difference is mainly driven by increased revascularizations in the CLO arm, but also by increased incidence of MI in the CLO subgroup with FFR+ lesions that were left untreated.

Sex-related response to bivalirudin and unfractionated heparin in patients with acute myocardial infarction undergoing percutaneous coronary intervention: A subgroup analysis of the VALIDATE-SWEDEHEART trial

Aims:

Our aim was to study the impact of sex on anticoagulant treatment outcomes during percutaneous coronary intervention in acute myocardial infarction patients.

Methods:

This study was a prespecified analysis of the Bivalirudin versus Heparin in ST-Segment and Non ST-Segment Elevation Myocardial Infarction in Patients on Modern Antiplatelet Therapy in the Swedish Web System for Enhancement and Development of Evidence-based Care in Heart Disease Evaluated according to Recommended Therapies Registry Trial (VALIDATE-SWEDEHEART) trial, in which patients with myocardial infarction were randomised to bivalirudin or unfractionated heparin during percutaneous coronary intervention. The primary outcome was the composite of death, myocardial infarction or major bleeding at 180 days.

Results:

There was a lower risk of the primary outcome in women assigned to bivalirudin than to unfractionated heparin (13.6% vs 17.1%, hazard ratio 0.78, 95% confidence interval (0.60–1.00)) with no significant difference in men (11.8% vs 11.2%, hazard ratio 1.06 (0.89–1.26), p for interaction 0.05). The observed difference was primarily due to lower risk of major bleeding (Bleeding Academic Research Consortium definition 2, 3 or 5) associated with bivalirudin in women (8.9% vs 11.8%, hazard ratio 0.74 (0.54–1.01)) but not in men (8.5% vs 7.3%, hazard ratio 1.16 (0.94–1.43) in men, p for interaction 0.02). Conversely, no significant difference in the risk of Bleeding Academic Research Consortium 3 or 5 bleeding, associated with bivalirudin, was found in women 4.5% vs 5.4% (hazard ratio 0.84 (0.54–1.31)) or men 2.9% vs 2.1% (hazard ratio 1.36 (0.93–1.99)). Bleeding Academic Research Consortium 2 bleeding occurred significantly less often in women assigned to bivalirudin than to unfractionated heparin. The risk of death or myocardial infarction did not significantly differ between randomised treatments in men or women.

Conclusion:

In women, bivalirudin was associated with a lower risk of adverse outcomes, compared to unfractionated heparin, primarily due to a significant reduction in Bleeding Academic Research Consortium 2 bleeds.

Takotsubo syndrome in hemodynamically unstable patients admitted to the intensive care unit - a retrospective study

INTRODUCTION

Takotsubo syndrome (TS) is an acute cardiac condition that is often triggered by critical illness but that has rarely been studied in the intensive care unit (ICU) setting. The aim of this study was to (i) estimate the incidence of TS in a hemodynamically unstable ICU-population; (ii) identify predictors of TS in this population; (iii) study the impact of TS on prognosis and course of hospitalization.

METHODS

Medical records from all patients admitted to our general ICU from 2012 to 2015 were analyzed. TS was defined as having transient regional wall motion abnormalities (RWMA) with a typical pattern not attributable to a history of coronary artery disease or acute coronary syndromes.

RESULTS

Out of 6470 patients admitted to the ICU, echocardiography due to hemodynamic instability was performed in 1051 patients; 467 had LV dysfunction and 59 fulfilled TS criteria. Patients with TS had higher SAPS 3 scores on admission than patients with normal LV function. Septic shock, cardiac arrest, cerebral mass lesion, female sex and low pH were independently associated with TS on admission. Patients with TS needed more ICU resources measured by higher NEMS scores and longer ICU-stay. Crude mortality was higher in TS patients (32%) vs the ICU-population (20%, P = 0.020), but there were no differences in a SAPS 3 adjusted analysis.

CONCLUSION

TS was not an uncommon cause of LV dysfunction in hemodynamically unstable ICU-patients. Furthermore, TS was associated with a more complex disease. TS is a complication to take in consideration in the critically ill.

Early treatment with isoflurane attenuates left ventricular dysfunction and improves survival in experimental Takotsubo

BACKGROUND

Takotsubo syndrome (TS) is an acute cardiac condition, often triggered by critical illness, for which no specific treatment exists. Previously, we showed that isoflurane can prevent experimental TS. The aim of this study was to evaluate the potential treatment effects of isoflurane. Our primary hypothesis was that early treatment with isoflurane attenuates left ventricular akinesia in experimental TS.

METHOD

In propofol-sedated animals, TS was induced by an intraperitoneal bolus of isoprenaline (50 mg/kg). Animals were randomized to one of six groups (n = 15 in each group), and 1% isoflurane was administered for 90 min in all groups. Isoflurane treatment was started at 0, 10, 30 (early treatment) or 120 (late treatment) minutes after isoprenaline injection. One additional late treatment group received isoflurane 0.5% for 180 min. A control group did not receive isoflurane. Left ventricular (LV) echocardiographic examination was performed at 90 min and 48 h after isoprenaline. Mortality was assessed at 48 h.

RESULTS

Median degree of LV akinesia at 90 min was 24% in the control group and 0% in the early treatment groups (P < 0.001). Stroke volume, cardiac output and LV ejection fraction were higher in the early treatment groups vs. controls (P < 0.01). Mortality was lower in the early treatment groups (24%) vs. controls (86%) (P < 0.001). Mortality did not differ between the late treatment groups and controls.

CONCLUSION

Early treatment with isoflurane attenuates the LV akinesia and improves survival in experimental TS. Isoflurane sedation in patients at risk of developing Takotsubo syndrome could be a subject for future studies.

Anaesthetic-induced cardioprotection in an experimental model of the Takotsubo syndrome - isoflurane vs. propofol

BACKGROUND

Takotsubo syndrome (TS) is an acute cardiac condition with a substantial mortality for which no specific treatment is available. We have previously shown that isoflurane attenuates the development of left ventricular (LV) dysfunction in an experimental TS-model. We compared the effects of equi-anaesthetic doses of isoflurane, propofol and ketamine+midazolam on haemodynamics, global and regional LV systolic function and the activation of intracellular metabolic pathways in experimental TS. We hypothesized that cardioprotection in experimental TS is specific for isoflurane.

METHODS

Forty-five rats were randomized to isoflurane (0.6 MAC, n = 15), propofol (bolus 200 mg/kg+360 mg/kg/h, n = 15) or ketamine (100 mg/kg)+midazolam (10 mg/kg, n = 15) anaesthesia. Arterial pressure, heart rate and body temperature were continuously measured and arterial blood gas analysis was performed intermittently. TS was induced by intraperitoneal injection of isoprenaline, 50 mg/kg. LV echocardiography was performed 90 min after isoprenaline injection. Apical cardiac tissue was analysed by global discovery proteomics and pathway analysis.

RESULTS

Isoprenaline-induced changes in arterial blood pressure, heart rate or body temperature did not differ between groups. LV ejection fraction was higher and extent of LV akinesia was lower with isoflurane, when compared with the propofol and the ketamine+midazolam groups. In this TS-model, the proteomic analysis revealed an up-regulation of pathways involved in inflammation, coagulation, endocytosis and lipid metabolism. This up-regulation was clearly attenuated with isoflurane compared to propofol.

CONCLUSION

In an experimental model of TS, isoflurane, but not propofol, exerts a cardioprotective effect. The proteomic analysis suggests that inflammation might be involved in pathogenesis of TS.

Importance of circulating IGF-1 for normal cardiac morphology, function and post infarction remodeling

IGF-1 plays an important role in cardiovascular homeostasis, and plasma levels of IGF-1 correlate inversely with systolic function in heart failure. It is not known to what extent circulating IGF-1 secreted by the liver and local autocrine/paracrine IGF-1 expressed in the myocardium contribute to these beneficial effects on cardiac function and morphology. In the present study, we used a mouse model of liver-specific inducible deletion of the IGF-1 gene (LI-IGF-1 -/- mouse) in an attempt to evaluate the importance of circulating IGF-I on cardiac morphology and function under normal and pathological conditions, with an emphasis on its regulatory role in myocardial phosphocreatine metabolism. Echocardiography was performed in LI-IGF-1 -/- and control mice at rest and during dobutamine stress, both at baseline and post myocardial infarction (MI). High-energy phosphate metabolites were compared between LI-IGF-1 -/- and control mice at 4 weeks post MI. We found that LI-IGF-1 -/- mice had significantly greater left ventricular dimensions at baseline and showed a greater relative increase in cardiac dimensions, as well as deterioration of cardiac function, post MI. Myocardial creatine content was 17.9% lower in LI-IGF-1 -/- mice, whereas there was no detectable difference in high-energy nucleotides. These findings indicate an important role of circulating IGF-1 in preserving cardiac structure and function both in physiological settings and post MI.

Effects of complete heart block on myocardial function, morphology, and energy metabolism in the rat

AIMS

Severe sustained bradycardia may cause acute and possibly chronic congestive heart failure (CHF). The aim of this study was to investigate acute and chronic effects of complete heart block (CHB) on cardiac function, morphology, and creatine (Cr) metabolism.

METHODS AND RESULTS

CHB was induced in male Sprague-Dawley rats (approximately 250 g, n = 11) by means of electrocautery applied to the region of AV node and were compared with controls (n = 15). The rats were investigated at 1, 3, and 12 weeks after CHB induction with transthoracic echocardiography. Invasive haemodynamic assessment of left and right ventricular pressures was performed at 12 weeks. After the sacrifice, the hearts were freeze-clamped for analysis of myocardial Cr, and high energy phosphometabolites. The efficacy of operative procedure was 54%. The peri-operative mortality rate was 20%. Heart rate (HR) decreased by approximately 50% (P < 0.01) while stroke volume (SV) increased 2.5 times (P < 0.01) in the CHB rats. Cardiac index remained unchanged. The rats with CHB grew normally and were in no apparent distress. Filling pressures in left and right ventricles were normal. The CHB rats developed marked cardiomegaly with biventricular dilatation and eccentric left ventricular hypertrophy (P < 0.01). There was no change in the myocardial content of Cr and high energy phosphometabolites.

CONCLUSION

Rats with CHB are compensating for reduction in HR with increased SV without haemodynamic and biochemical characteristics of CHF. This model may be useful to study the effects of CHB and bradycardia on myocardial structure, function, electrophysiology, and metabolism as well as for studies of cell therapy for reparation of AV conductance.

In vivo MR imaging of magnetically labeled human embryonic stem cells

INTRODUCTION

Human embryonic stem cells (hES) have emerged as a potentially new therapeutic approach for treatment of heart and other diseases applying the concept of regenerative medicine. A method for in vivo visualization and tracking of transplanted hES would increase our understanding of in vivo hES behavior in both experimental and clinical settings. The aim of this study was to evaluate the feasibility of magnetic labeling and visualization of hES with magnetic resonance imaging (MRI).

METHODS

hES were established and expanded according to standard procedures. After expansion, the cells were cultured under feeder free conditions and magnetically labeled by addition of dextran-coated Ferrum-oxide particles (Endorem) to the medium. Accumulation of small particles of iron-oxide (SPIO) in hES was assessed by Prussian blue staining and electron microscopy. For in vitro MRI, the labeled and unlabeled hES were examined in cell solution and after transplantation into explanted mouse heart ( approximately 100,000 cells) on a Bruker Avance DMX 500 vertical magnet at 11.75 T. A multi-slice, multi spin-echo T(2)-weighted images were obtained. For in vivo imaging, the experiments were performed on male Sprague-Dawley using Bruker Biospec 2.35 T magnet. The hES were directly injected ( approximately 500,000 cells) after surgical procedure (thoracotomy) into anterior left ventricular (LV) wall. Multi-slice T(2)-weighted gradient echo images were obtained using cardiac gating.

RESULTS

hES appeared to be unaffected by magnetic labeling and maintained their ability to proliferate and differentiate. No additive agent for membrane permeabilisation was needed for facilitation of intracellular SPIO accumulation. Prussian blue and electron microscopy have revealed numerous iron particles in the cytoplasm of hES. On T(2)-weighted images, the labeled cells have shown well-defined hyopintense areas at the site of injection in anterior LV wall both in vitro and in vivo.

CONCLUSIONS

It is feasible to magnetically label and visualize hES both in vitro and in vivo. MR visualization of magnetically labeled hES may be a valuable tool for in vivo tracking of hES.

Selective cerebral overexpression of growth hormone alters cardiac function, morphology, energy metabolism and catecholamines in transgenic mice

BACKGROUND

Growth hormone (GH) has important regulatory effects on cardiac morphology and function both during normal development as well as in pathophysiological settings such as myocardial infarction (MI) and congestive heart failure (CHF). In order to investigate in more detail the interaction between GH and sympathetic nervous system (SNS) system we studied the effects of selective cerebral GH overexpression on myocardial content of catecholamines, myocardial and brain energy metabolism as well as on cardiac function during resting and stress conditions in a transgenic mouse model.

METHODS

Transgenic mice with selective bovine GH overexpression under control of glial fibrillary acidic protein promoter in the brain (GFAP-bGH, n=15) were created and compared to genetically matched non-transgenic mates (Control, n=15). Cardiac morphology and function were evaluated in vivo using transthoracic echocardiography during resting and stress conditions induced pharmacologically by dopamine (D) and isoprotenolol (ISO). Myocardial and brain energy metabolism were evaluated non-invasively using in vivo volume-selective phosphorus magnetic resonance spectroscopy ((31)P MRS). Myocardial content of catecholamines was analyzed by means of HPLC.

RESULTS

Compared to the C animals, the GFAP-bGH mice have showed several differences in the cardiac phenotype. Systolic (fractional shortening) and diastolic function (E/A wave ratio of mitral flow) was disturbed in the GFAP-bGH mice (both p<0.05). During the dopamine stress, there was chronotropic insufficiency in the GFAP-bGH group (p<0.01) while no difference was observed in response to isoprotenolol. Left ventricular dimensions were increased in GFAP-bGH mice (p<0.05). There was a tendency for higher body weight in GFAP-bGH compared to the control group (p=0.06) while no difference was observed in heart weight and brain weight when normalized for body weight. Myocardial content of noradrenaline was lower in the GFAP-bGH group (p<0.05). PCr/ATP ratio was higher (p<0.05) in the brain and lower in the heart (p<0.05) in the GFAP-bGH mice.

CONCLUSIONS

Selective cerebral overexpression of GH results in alterations of cardiac function, morphology and metabolism in transgenic mice. Decreased myocardial content of catecholamines in the GFAP-bGH mice suggests central interaction between GH and sympathetic nervous system.

Selective β1-blockade attenuates post-infarct remodelling without improvement in myocardial energy metabolism and function in rats with heart failure

OBJECTIVE

To investigate in vivo effects of long-term selective beta1-blockade on cardiac energy metabolism, remodelling, function and plasma cytokines in a rat model of post-infarct congestive heart failure (CHF).

METHODS

Myocardial infarction (MI) was induced in male rats by ligation of the left coronary artery. Three different groups of rats were studied, MI rats treated with metoprolol (n=17), MI rats treated with saline (n=14) and sham-operated rats (n=12). The treatment with metoprolol 1 mg/kg/h was initiated in the third week post-infarct for a period of 6 weeks. All rats were investigated non-invasively with volume-selective 31P magnetic resonance spectroscopy and echocardiography for evaluation of left ventricular (LV) energy metabolism, morphology and function. Plasma concentration of IL-1beta and IL-6 and density of beta-adrenergic receptors were analyzed.

RESULTS

Metoprolol attenuated the increase in LV dimensions and volumes. Treatment with metoprolol had no effect on PCr/ATP and LV function. Plasma level of IL-1beta was higher and IL-6 was lower in the metoprolol group. Density of beta-adrenergic receptors was similar in all three groups.

CONCLUSION

Selective beta1-blockade in rats with chronic CHF attenuates post-infarct structural remodelling, without concomitant improvement in myocardial energy metabolism and function. Improvements in myocardial energy metabolism and function do not precede and are not a prerequisite for an anti-remodelling effect of beta1-blockade in the setting of chronic CHF.

Growth hormone alone or combined with metoprolol preserves cardiac function after myocardial infarction in rats

BACKGROUND AND OBJECTIVE

Beta-adrenoreceptor blocking agents are important for the treatment of myocardial infarction (MI). Accumulating evidence also indicates that growth hormone (GH) improves cardiac function after MI in rats. We aimed to investigate the cardiovascular effects of combined treatment in an animal model of MI.

METHODS

MI was induced in rats by ligation of the left coronary artery. Three days after MI, animals were randomly assigned to one of four groups: controls (C) (n=19); GH (n=19) receiving s.c. 2 mg/kg per day rhGH; metoprolol (M) group (n=19) receiving 24 mg/kg per day and combined group (GHM) (n=20) treated with both GH (2 mg/kg per day s.c.) and M (24 mg/kg per day) for 9 days. Transthoracic echocardiography was performed before and after treatment.

RESULTS

Serum levels of insulin-like growth factor I were significantly elevated in the GH-group but not in the GHM group compared to controls. Left ventricular volumes, cardiac index, systolic blood pressure, were similar in all groups. Percent changes in ejection fraction compared to baseline were; GH (6.1+/-5.0%) and GHM (6.1+/-4.2%) vs. C (-12.5+/-3.0%), P<0.01, M (-7.3+/-4.2%). The occurrence of aneurysms was not significantly different between the various treatment regimes.

CONCLUSION

Treatment with growth hormone alone or in combination with metoprolol preserved left ventricular function after MI.

Selective beta(1)-blockade improves cardiac bioenergetics and function and decreases neuroendocrine activation in rats during early postinfarct remodeling

In spite of the solid evidence that beta-blockade reduces mortality and morbidity in congestive heart failure (CHF) this therapy continues to be underused in clinical praxis. The reason for this may lie in scarcity of knowledge about the mechanisms of beta-blockade action. The major aim of this study was to investigate in vivo whether selective beta(1)-blockade may improve cardiac energy metabolism in rats with myocardial infarction in early postinfarct remodeling phase. Myocardial infarction (MI) was induced in male Sprague-Dawley rats by ligation of the left coronary artery. Two different groups of rats were studied, rats with MI treated with metoprolol (5 mg/kg/h; n = 9) and rats with MI saline treated (n = 9). The treatment with metoprolol was given by subcutaneously implanted minipumps and was initiated at 3 days postinfarct and during the period of 4 weeks. All rats were investigated with noninvasive methods (31)P magnetic resonance spectroscopy (MRS) and transthoracic echocardiography 3 days after induction of MI and 4 weeks later. Phosphocreatine/ATP ratio was normalized after the treatment with metoprolol while it was 50% lower in the saline group (p < 0.001). In the metoprolol group stroke volume and ejection fraction increased while deceleration time of mitral early filling was longer (all p < 0.05). Left ventricular weight as well as volumes and dimensions were similar between the groups. Plasma levels of noradrenaline (p = 0.058), adrenaline (p < 0.01) and brain natriuretic peptide (p = 0.09) were lower in the metoprolol group. Selective beta(1)-blockade with high dose of metoprolol initiated in the early postinfarct phase improves myocardial energy metabolism and function and prevents overactivation of sympathetic system. The beneficial effect on myocardial bioenergetics may be an important mode of action of beta-blockers which contributes to the clinical benefits of the therapy in CHF.

Growth hormone improves bioenergetics and decreases catecholamines in postinfarct rat hearts

The aims of this study were to examine, in vivo, the effects of GH treatment on myocardial energy metabolism, function, morphology, and neurohormonal status in rats during the early postinfarct remodeling phase. Myocardial infarction (MI) was induced in male Sprague Dawley rats. Three different groups were studied: MI rats treated with saline (n = 7), MI rats treated with GH (MI + GH; n = 11; 3 mg/kg x day), and sham-operated rats (sham; n = 8). All rats were investigated with 31P magnetic resonance spectroscopy and echocardiography at 3 days after MI and 3 weeks later. After 3 weeks treatment with GH, the phosphocreatine/ATP ratio increased significantly, compared with the control group (MI = 1.69 +/- 0.09 vs. MI + GH = 2.42 +/- 0.05, P < 0.001; sham = 2.34 +/- 0.08). Treatment with GH significantly attenuated an increase in left ventricular end systolic volume and end diastolic volume. A decrease in ejection fraction was prevented in GH-treated rats (P < 0.05 vs. MI). Myocardial and plasma noradrenaline levels were significantly lower in MI rats treated with GH. These effects were accompanied by normalization of plasma brain natriuretic peptide levels (sham = 124.1 +/- 8.4; MI = 203.9 +/- 34.7; MI + GH = 118.3 +/- 8.4 ng/ml; P < 0.05 vs. MI). In conclusion, GH improves myocardial energy reserve, preserves left ventricular function, and attenuates pathologic postinfarct remodeling in the absence of induction of left ventricular hypertrophy in postinfarct rats. The marked decrease in myocardial content of noradrenaline, after GH treatment, may protect myocardium from adverse effects of catecholamines during postinfarct remodeling.

Induction of cardiomyopathy in severe combined immunodeficiency mice by transfer of lymphocytes from patients with idiopathic dilated cardiomyopathy

Growing evidence suggests that autoimmune mechanisms play an important role in the pathogenesis of idiopathic dilated cardiomyopathy (DCM). The aim of the study was to evaluate the effects of transfer of lymphocytes from patients with DCM into severe combined immunodeficiency (SCID) mice on the heart structure and function. Thirty CB-17 SCID (6-8 weeks old) mice were used and divided into 3 groups (n = 10). Mice were injected intraperitoneally with up to 25 x 10(6) peripheral blood lymphocytes (PBL) from either patients with DCM which contain human autoantibodies against cardiac beta1-adrenergic receptors and M2-muscarinic receptors (DCM group) or PBL from healthy controls (control-H group). Ten mice did not receive any injections and were used as baseline controls (control-N group). Echocardiography and morphological studies were performed seventy five days after the transfer. Results showed that in DCM group, left ventricle dimensions (LVD) in diastole were increased (4.2 +/- 0.1mm) as compared to both control-H group (3.8 +/- 0.1mm) and control-N group (3.6 +/- 0.1 mm) (p < 0.01). Further, there was a trend for increased LVD in systole. Fractional shortening was not different between groups. Histological evaluation revealed accumulation of human lymphocytes in the capillaries and scarce infiltration of the lymphocytes in the hearts from DCM group. Diffuse fibrosis was significant increased in DCM mice as compared to mice receiving PBL from normal subjects (2.2 +/- 0.3% vs. 0.8 +/- 0.1%, p < 0.01). In conclusion, transfer of the PBL from the patients with DCM was able to induce early stage of heart dilatation in SCID mice. These data provide for the first time the direct evidence supporting that the autoimmune mechanism is important in the pathogenesis of human DCM.

Impairment of cardiac function and bioenergetics in adult transgenic mice overexpressing the bovine growth hormone gene

Cardiovascular abnormalities represent the major cause of death in patients with acromegaly. We evaluated cardiac structure, function, and energy status in adult transgenic mice overexpressing bovine GH (bGH) gene. Female transgenic mice expressing bGH gene (n = 11) 8 months old and aged matched controls (n = 11) were used. They were studied with two-dimensional guided M-mode and Doppler echocardiography. The animals (n = 6) for each group were examined with 31P magnetic resonance spectroscopy to determine the cardiac energy status. Transgenic mice had a significantly higher body weight (BW), 53.2+/-2.4 vs. 34.6+/-3.7 g (P < 0.0001) and hypertrophy of left ventricle (LV) compared with normal controls: LV mass/BW 5.6+/-1.6 vs. 2.7+/-0.2 mg/g, P < 0.01. Several indexes of systolic function were depressed in transgenic animals compared with controls mice such as shortening fraction 25+/-3.0% vs. 39.9+/-3.1%; ejection fraction, 57+/-9 vs. 77+/-5; mean velocity of circumferential shortening, 4.5+/-0.8 vs. 7.0+/-1.1 circ/sec, p < 0.01. Creatine phosphate-to-ATP ratio was significantly lower in bGH overexpressing mice (1.3+/-0.08 vs. 2.1+/-0.23 in controls, P < 0.05). Ultrastructural examination of the hearts from transgenic mice revealed substantial changes of mitochondria. This study provides new insight into possible mechanisms behind the deteriorating effects of long exposure to high level of GH on heart function.

In vivo metabolic imaging of cardiac bioenergetics in transgenic mice

Recent advances in transgenic technology have made the mouse a particularly interesting small animal in cardiovascular research. Increasingly sophisticated experimental methods and tools are needed for detailed characterization of cardiovascular physiology and biochemistry in the mice. The objective of this study was to develop a method for noninvasive evaluation of cardiac energy metabolism in the mouse. Cardiac gated (31)P magnetic resonance spectroscopy using Image Selected in Vivo Spectroscopy (ISIS) method was applied in old mice overexpressing bovine growth hormone (bGH) (n = 5) and control mice (n = 5). The localized volumes of interest were 128 and 112 microL, respectively. Phosphocreatine-to-ATP ratio was 1.5 +/- 0.13 in the bGH mice and 2.1 +/- 0.04 in the control group (P < 0.01). The study demonstrates the feasibility of application of volume-selective (31)P MRS for evaluation of cardiac energy metabolism in the mouse under maintained physiological conditions.