Comparative Effectiveness of β-Blocker Use Beyond 3 Years After Myocardial Infarction and Long-Term Outcomes Among Elderly Patients

Guideline-directed Medical Therapy in Nonagenarians and Centenarians (≥ 90 Years Old) After First-onset Myocardial Infarction---a National Registry Study

BACKGROUND

Guideline-directed medical therapies (GDMTs), such as beta-blockers, antiplatelet drugs, lipid-lowering drugs, and renin-angiotensin system agents, have been associated with reduced risk of mortality after acute myocardial infarction (AMI). However, this survival benefit conferred by GDMTs in nonagenarians and centenarians (≥ 90 years old) is not well-defined.

METHODS

We investigated restricted mean survival times of patients ≥ 90 years of age with first-onset AMI treated with GDMTs from 2007 to 2020 in the Singapore Myocardial Infarction Registry. Primary analyses involved stratification by number of GDMTs prescribed at discharge, with derivation of pairwise restricted mean survival ratios free from all-cause mortality at 1, 3, and 5 years. Secondary analyses evaluated individual GDMTs within combinations of 1-3 GDMTs.

RESULTS

The analysis included 3264 patients: 0 GDMTs (561 patients, 17.2%), 1-2 GDMTs (1294 patients, 39.6%), 3 GDMTs (904 patients, 27.7%), and 4 GDMTs (505 patients, 15.5%), with a median follow-up duration of 5.71 years. Patients who received 4 GDMTs at discharge were younger, had more comorbidities, were more likely to be smokers, and were more likely to have undergone percutaneous coronary intervention than those prescribed fewer GDMTs. A greater number of GDMT classes at discharge was associated with longer survival free from all-cause mortality at 1, 3, and 5 years. Each drug class within combinations of 1-3 GDMTs was associated with significant survival benefit at all time points, except for beta-blockers.

CONCLUSIONS

Prescription of any number of GDMTs to nonagenarians and centenarians after first-onset AMI is associated with significant survival benefit.

Management of Acute Coronary Syndromes in Older People: Comprehensive Review and Multidisciplinary Practice-Based Recommendations

Managing health care for older adults aged 75 years and older can pose unique challenges stemming from age-related physiological differences and comorbidities, along with elevated risk of delirium, frailty, disability, and polypharmacy. This review is aimed at providing a comprehensive analysis of the management of acute coronary syndromes (ACS) in older patients, a demographic substantially underrepresented in major clinical trials. Because older patients often exhibit atypical ACS symptoms, a nuanced diagnostic and risk stratification approach is necessary. We aim to address diagnostic challenges for older populations and highlight the diminished sensitivity of traditional symptoms with age, and the importance of biomarkers and imaging techniques tailored for older patients. Additionally, we review the efficacy and safety of pharmacological agents for ACS management in older people, emphasizing the need for a personalized and shared decision-making approach to treatment. This review also explores revascularization strategies, considering the implications of invasive procedures in older people, and weighing the potential benefits against the heightened procedural risks, particularly with surgical revascularization techniques. We explore the perioperative management of older patients experiencing myocardial infarction in the setting of noncardiac surgeries, including preoperative risk stratification and postoperative care considerations. Furthermore, we highlight the critical role of a multidisciplinary approach involving cardiologists, geriatricians, general and internal medicine physicians, primary care physicians, and allied health, to ensure a holistic care pathway in this patient cohort.

Pharmacotherapy for Coronary Artery Disease and Acute Coronary Syndrome in the Aging Population

PURPOSE OF REVIEW

To provide a comprehensive summary of relevant studies and evidence concerning the utilization of different pharmacotherapeutic and revascularization strategies in managing coronary artery disease and acute coronary syndrome specifically in the older adult population.

RECENT FINDINGS

Approximately 30% to 40% of hospitalized patients with acute coronary syndrome are older adults, among whom the majority of cardiovascular-related deaths occur. When compared to younger patients, these individuals generally experience inferior clinical outcomes. Most clinical trials assessing the efficacy and safety of various therapeutics have primarily enrolled patients under the age of 75, in addition to excluding those with geriatric complexities. In this review, we emphasize the need for a personalized and comprehensive approach to pharmacotherapy for coronary heart disease and acute coronary syndrome in older adults, considering concomitant geriatric syndromes and age-related factors to optimize treatment outcomes while minimizing potential risks and complications. In the realm of clinical practice, cardiovascular and geriatric risks are closely intertwined, with both being significant factors in determining treatments aimed at reducing negative outcomes and attaining health conditions most valued by older adults.

Prognostic Impact of Early Administration of β-Blockers in Critically Ill Patients with Acute Myocardial Infarction

In critically ill patients with acute myocardial infarction (AMI), the relationship between the early administration of β-blockers and the risks of in-hospital and long-term mortality remains controversial. Furthermore, there are conflicting evidences for the efficacy of the early administration of intravenous followed by oral β-blockers in AMI. We conducted a retrospective analysis of critically ill patients with AMI who received the early administration of β-blockers within 24 hours of admission. The data were extracted from the Medical Information Mart for Intensive Care IV database. We enrolled 2467 critically ill patients with AMI in the study, with 1355 patients who received the early administration of β-blockers and 1112 patients who were non-users. Kaplan-Meier survival analysis and Cox proportional hazards models showed that the early administration of β-blockers was associated with a lower risk of in-hospital mortality (adjusted hazard ratio [aHR] 0.52; 95% confidence interval [95%CI] 0.42-0.64), 1-year mortality (aHR 0.54, 95%CI 0.47-0.63), and 5-year mortality (aHR 0.60, 95%CI 0.52-0.69). Furthermore, the early administration of both oral β-blockers and intravenous β-blockers followed by oral β-blockers may reduce the mortality risk, compared with non-users. The risks of in-hospital and long-term mortality were significantly decreased in patients who underwent revascularization with the early administration of β-blockers. We found that the early administration of β-blockers could lower the risks of in-hospital and long-term mortality. Furthermore, the early administration of both oral β-blockers and intravenous β-blockers followed by oral β-blockers may reduce the mortality risk, compared with non-users. Notably, patients who underwent revascularization with the early administration of β-blockers showed the lowest risks of in-hospital and long-term mortality.

Association of β-blocker use at discharge and prognosis of oldest old with acute myocardial infarction: a prospective cohort study

PURPOSE

It is uncertain whether β-blockers are beneficial for long-term prognosis in older patients following acute myocardial infarction (AMI). Thus, this study sought to examine the effect of β-blockers on long-term cardiovascular mortality (CVM) in the oldest old (≥ 80 years) with AMI.

METHODS

In this prospective, consecutive, non-randomized study, a total of 1156 patients with AMI admitted within 24 h after onset of symptoms were enrolled from January 2012 to February 2020. Univariate and multivariate Cox regression analyses were performed to examine the impact of β-blocker use on prognosis. Furthermore, one-to-one propensity score matching (PSM) and inverse probability treatment weighting (IPTW) analyses were used to control for systemic differences between groups. The primary outcome was long-term CVM.

RESULTS

Among the enrolled subjects, 972 (85.9%) were prescribed with β-blockers at discharge. Over a mean follow-up of 26.3 months, 224 cardiovascular deaths were recorded. Both univariate [hazard ratio (HR), 1.41, 95% confidence interval (CI) 0.93-2.13] and multivariate (HR, 1.29, 95% CI 0.79-2.10) Cox regression analyses showed that β-blocker use had no significant association with the long-term CVM, which was further demonstrated by PSM (HR, 1.31, 95% CI 0.75-2.28) and IPTW (HR, 1.41, 95% CI 0.73-2.69) analyses. Subgroup analyses according to sex, heart rate, hypertension, diabetes, revascularization, left ventricular ejection fraction, and angiotensin-converting enzyme inhibitors/angiotensin receptor blockers use showed consistent results as well.

CONCLUSION

Our findings first suggested that the use of β-blockers at discharge in oldest old with AMI was not useful for reducing post-discharge CVM, which need to be further verified by randomized controlled trials.

Differences in treatment and clinical outcomes in patients aged ≥75 years compared with those aged ≤74 years following acute coronary syndromes: a prospective multicentre study

OBJECTIVE

This study describes the differences in treatment and clinical outcomes in patients aged ≥75 years compared with those aged ≤74 years presenting with acute coronary syndrome (ACS) and undergoing invasive management.

METHODS

A large-scale cohort study of patients with ST-elevation/non-ST-elevation myocardial infarction (MI)/unstable angina underwent coronary angiography (January 2015-December 2019). Patients were classified as older (≥75 years) and younger (≤74 years). Regression analysis was used to yield adjusted risks of mortality for older versus younger patients (adjusted for history of heart failure, hypercholesterolaemia, peripheral vascular disease, chronic obstructive pulmonary disease, ischaemic heart disease, presence of ST-elevation MI on presenting ECG, female sex and cardiogenic shock at presentation).

RESULTS

In total, 11 763 patients were diagnosed with ACS, of which 39% were aged ≥75 years. Percutaneous coronary intervention was performed in fewer older patients than younger patients (81.2% vs 86.2%, p<0.001). At discharge, older patients were prescribed less secondary-prevention medications than younger patients. Median follow-up was 4.57 years. Older patients had a greater risk of in-hospital mortality than younger patients (adjusted OR (aOR) 2.12, 95% CI 1.62 to 2.78, p<0.001). Older patients diagnosed with ST-elevation MI had greater adjusted odds of dying in-hospital (aOR 2.47, 95% CI 1.79 to 3.41, p<0.001). Older age was not an independent prognostic factor of mortality at 1 year (adjusted HR (aHR) 0.95, 95% CI 0.82 to 1.09, p=0.460) and at longer term (aHR 0.98, 95% CI 0.87 to 1.10, p=0.684).

CONCLUSIONS

Older patients are discharged with less secondary prevention. Patients aged ≥75 years are more likely to die in-hospital than younger patients.

Beyond MACE: a multidimensional approach to outcomes in clinical trials for older adults with stable ischemic heart disease

The global population of older adults is expanding rapidly resulting in a shift towards managing multiple chronic diseases that coexist and may be exacerbated by cardiovascular illness. Stable ischemic heart disease (SIHD) is a predominant contributor to morbidity and mortality in the older adult population. Although results from clinical trials demonstrate that chronological age is a predictor of poor health outcomes, the current management approach remains suboptimal due to insufficient representation of older adults in randomized trials and the inadequate consideration for the interaction between biological aging, concurrent geriatric syndromes, and patient preferences. A shift towards a more patient-centered approach is necessary for appropriately and effectively managing SIHD in the older adult population. In this review, we aim to demonstrate the distinctive needs of older adults who prioritize holistic health outcomes like functional capacity, cognitive abilities, mental health, and quality of life alongside the prevention of major adverse cardiovascular outcomes reported in cardiovascular clinical trials. An individualized, patient-centered approach that involves shared decision-making regarding outcome prioritization is needed when any treatment strategy is being considered. By prioritizing patients and addressing their unique needs for successful aging, we can provide more effective care to a patient population that exhibits the highest cardiovascular risks.

Comparative Effectiveness of Long-Term Maintenance Beta-Blocker Therapy After Acute Myocardial Infarction in Stable, Optimally Treated Patients Undergoing Percutaneous Coronary Intervention

Background The benefits of long-term maintenance beta-blocker (BB) therapy in patients with acute myocardial infarction (AMI) undergoing percutaneous coronary intervention (PCI) have not been well established. Methods and Results Using the Korean nationwide registry, a total of 7159 patients with AMI treated with PCI who received BBs at discharge and were free from death or cardiovascular events for 3 months after PCI were included in the analysis. Patients were divided into 4 groups according to BB maintenance duration: <12 months, 12 to <24 months, 24 to <36 months, and ≥36 months. The primary outcome was the composite of all-cause death, recurrent MI, heart failure, or hospitalization for unstable angina. During a mean 5.0±2.8 years of follow-up, over half of patients with AMI (52.5%) continued BB therapy beyond 3 years following PCI. After propensity score matching and propensity score marginal mean weighting through stratification, a stepwise inverse correlation was noted between BB duration and risk of the primary outcome (<12 months: hazard ratio [HR], 2.19 [95% CI, 1.95-2.46]; 12 to <24 months: HR, 2.10 [95% CI, 1.81-2.43];, and 24 to <36 months: HR, 1.68 [95%CI, 1.45-1.94]; reference: ≥36 months). In a 3-year landmark analysis, BB use for <36 months was associated with an increased risk of the primary outcome (adjusted HR, 1.59 [95% CI, 1.37-1.85]) compared with BB use for ≥36 months. Conclusions Among stabilized patients with AMI following PCI, longer maintenance BB therapy, especially for >36 months, was associated with better clinical outcomes. These findings might imply that a better prognosis can be expected if patients with AMI maintain BB therapy for ≥36 months after PCI. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02806102.

Long-Term Follow-Up After Acute Myocardial Infarction According to Beta-Blocker Dose

OBJECTIVE

Our purpose was to examine the association between beta-blocker dose and mortality following acute myocardial infarction.

METHODS

This nationwide cohort study enrolled all patients admitted for first-time acute myocardial infarction in Denmark between July 1, 2004 and December 31, 2014, using the Danish National Patient Registry. Patients alive 15 days after admission were followed until death, emigration, or December 31, 2014. Patients were categorized according to daily beta-blocker consumption (0%, >0%-12.5%, >12.5%-25%, >25%-50%, >50%-100%, or >100% of the currently recommended target dose) based on prescriptions registered in the Danish National Database of Reimbursed Prescriptions. Doses were continuously updated during follow-up. Mortality rate ratios (MRRs) were computed and adjusted for confounders using Cox proportional hazard regression.

RESULTS

Among 65,125 patients followed, any beta-blocker dose was associated with significant mortality reduction compared with no treatment (adjusted MRR ≤ 0.92 [95% confidence interval {CI}: 0.86-0.98]). The largest reduction was observed within the first year for beta-blocker doses >25%-50% (adjusted MRR = 0.55 [95% CI: 0.50-0.60]). After 1 year, doses >50%-100% were associated with the largest mortality reduction (adjusted MRR = 0.58 [95% CI: 0.50-0.67]), but it did not differ significantly from that associated with doses >25%-50% (adjusted MRR = 0.68 [95% CI: 0.61-0.77]).

CONCLUSIONS

Any beta-blocker dose was associated with significant mortality reduction following acute myocardial infarction compared with no treatment. Doses >25%-50% of the currently recommended target dose were associated with maximal mortality reduction within the first year after acute myocardial infarction, suggesting that higher doses are unnecessary.

Randomized evaluation of routine beta-blocker therapy after myocardial infarction quality of life (RQoL): design and rationale of a multicentre, prospective, randomized, open, blinded endpoint study

Aims

Most cases of acute myocardial infarction (MI) in Sweden are treated with long-term β-blocker therapy as secondary prevention. Case studies and patient reports have indicated negative effects of β-blockers including symptoms of depression, fatigue, sexual dysfunction, and general low mood, all related to reduced quality of life (QoL). To date, no recent large-scale, randomized trial has explored the effects of β-blockers on these factors.

Methods and results

The ongoing Randomized Evaluation of Decreased Usage of beta-bloCkErs after myocardial infarction (REDUCE): quality of life (RQoL) study is a multicentre, prospective, randomized pre-specified substudy aiming to evaluate the effects of β-blockers on self-reported measures of QoL. Following randomized allocation to long-term β-blocker or no β-blocker treatment, patients complete a total of six baseline measures pertaining to QoL, sexual functioning, and perceived side effects. Data collection is optionally carried out online through a unique and secure portal and repeated again at two follow-up time points. Recruitment began in July 2018. Data from the first 100 patients showed that at the first follow-up, 93% had completed the questionnaires, which decreased to 81% at the second follow-up. The method of digital data collection was utilized by over half of the patients recruited so far.

Conclusion

Data from the first 100 patients indicate success in terms of study design and recruitment. The RQoL substudy investigates the effects of β-blockers on self-reported measures of QoL in MI patients and will potentially contribute to the limited knowledge of QoL-related side effects reported in conjunction with β-blocker use.

Clinical trial registration

Eudra CT number, 2017-002336-17; Clinical trial.gov identifier, NCT03278509.

Association of Major Adverse Cardiac Events and Beta-Blockers in Patients with and without Atherosclerotic Cardiovascular Disease: Long-Term Follow-Up Results of the T-SPARCLE and T-PPARCLE Registry in Taiwan

Beta-blockers are widely used, but the benefit is now challenged in patients at risk of atherosclerotic cardiovascular disease (ASCVD) in the present coronary reperfusion era. We aimed to identify the risk factors of a major adverse cardiac event (MACE) and the long-term effect of beta-blockers in two large cohorts in Taiwan. Two prospective observational cohorts, including patients with known atherosclerosis cardiovascular disease (T-SPARCLE) and patients with at least one risk factor of ASCVD but without clinically evident ASCVD (T-PPARCLE), were conducted in Taiwan. The primary endpoint is the time of first occurrence of a MACE (cardiovascular death, nonfatal stroke, nonfatal myocardial infarction, and cardiac arrest with resuscitation). Between December 2009 and November 2014, with a median 2.4 years follow-up, 11,747 eligible patients (6921 and 4826 in T-SPARCLE and T-PPARCLE, respectively) were enrolled. Among them, 273 patients (2.3%) met the primary endpoint. With multivariate Cox PH model analysis, usage of beta-blocker was lower in patients with MACE (42.9% vs. 52.4%, p < 0.01). In patients with ASCVD, beta-blocker usage was associated with lower MACEs (hazard ratio 0.72; p < 0.001), but not in patients without ASCVD. The event-free survival of beta-blocker users remained higher during the follow-up period (p < 0.005) of ASCVD patients. In conclusion, in ASCVD patients, reduced MACE was associated with beta-blocker usage, and the effect was maintained during a six-year follow-up. Prescribing beta-blockers as secondary prevention is reasonable in the Taiwanese population.

Management of Acute Coronary Syndrome in the Older Adult Population: A Scientific Statement From the American Heart Association

Diagnostic and therapeutic advances during the past decades have substantially improved health outcomes for patients with acute coronary syndrome. Both age-related physiological changes and accumulated cardiovascular risk factors increase the susceptibility to acute coronary syndrome over a lifetime. Compared with younger patients, outcomes for acute coronary syndrome in the large and growing demographic of older adults are relatively worse. Increased atherosclerotic plaque burden and complexity of anatomic disease, compounded by age-related cardiovascular and noncardiovascular comorbid conditions, contribute to the worse prognosis observed in older individuals. Geriatric syndromes, including frailty, multimorbidity, impaired cognitive and physical function, polypharmacy, and other complexities of care, can undermine the therapeutic efficacy of guidelines-based treatments and the resiliency of older adults to survive and recover, as well. In this American Heart Association scientific statement, we (1) review age-related physiological changes that predispose to acute coronary syndrome and management complexity; (2) describe the influence of commonly encountered geriatric syndromes on cardiovascular disease outcomes; and (3) recommend age-appropriate and guideline-concordant revascularization and acute coronary syndrome management strategies, including transitions of care, the use of cardiac rehabilitation, palliative care services, and holistic approaches. The primacy of individualized risk assessment and patient-centered care decision-making is highlighted throughout.

Association between β-blocker dose and quality of life after myocardial infarction: a real-world Swedish register-linked study

BACKGROUND

β-blockers are routinely administered to patients following myocardial infarction (MI), yet their potential effect on health-related quality of life (HRQoL) is not entirely understood. We investigated the relationship between two different doses of β-blockers with HRQoL following MI.

METHODS AND RESULTS

This nationwide observational study used Swedish national registries to collate sociodemographic, clinical, medication, and HRQoL {the latter operationalized using EuroQol [European Quality of Life Five Dimensions Questionnaire (EQ-5D)]}. Estimates at 6-10 weeks and 12-14 months post-MI follow-up from pooled linear and logistic models were calculated after multiple imputation. We identified 35 612 patients with first-time MI, discharged with β-blockers, and enrolled in cardiac rehabilitation between 2006 and 2015. Upon discharge, patients were either dispensed <50% [24 082 (67.6%)] or ≥50% [11 530 (32.4%)] of the target dosage, as defined in previous trials. After adjusting for pre-defined covariates, neither the EQ-5D Index nor the Emotional Distress items were statistically different between groups. The EQ-VAS score was significantly lower in patients treated with ≥50% target β-blocker dose than those treated with <50% of the target dose [-0.87 [-1.23, -0.46], P < .001]. Results were similar at the 12-month follow-up and across sub-groups separated by sex and age.

CONCLUSION

No difference in HRQoL was found among patients taking <50% vs. ≥50% of the target β-blocker dose, except for the EQ-VAS in which higher scores were reported in those taking a lower dose. The clinical meaningfulness of this statistical significance is likely low.

Optimal cardiovascular medical therapy: current guidelines and new developments

Coronary artery disease is a leading cause of mortality worldwide, and patients with obstructive coronary artery disease require optimal cardiovascular medical therapy along with lifestyle modification for secondary prevention of future cardiac events. Optimal medical therapy includes antiplatelet agents, high-intensity statins, beta-blockers, angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, aldosterone antagonists, and calcium channel blockers. There are differences in the medical therapy guidelines of the American Heart Association/American College of Cardiology and the European Society of Cardiology. In addition, there are emerging medical therapies that may be added to future guidelines with additional cardiovascular outcome benefits.

Long-Term Effect of β-Blocker Use on Clinical Outcomes in Postmyocardial Infarction Patients: A Systematic Review and Meta-Analysis

BACKGROUND

Prior studies provided inconsistent results regarding long-term effect of β-blocker use on clinical outcomes in postmyocardial infarction (MI) patients.

METHODS

We searched for articles regarding long-term effect of β-blocker use on clinical outcomes in patients after MI and published them before July 2021 in the databases as follows: PubMed, Web of Science, MEDLINE, EMBASE, and Google Scholar. STATA 12.0 software was used to compute hazard ratios (HRs) and their 95% confidence intervals (CIs).

RESULTS

The study indicated that β-blocker group had significantly lower long-term all-cause mortality, cardiovascular mortality, major adverse cardiac events (MACEs) in post-MI patients, compared to no β-blocker group (all-cause mortality: HR, 0.67; 95% CI: 0.56-0.80; cardiovascular mortality: HR, 0.62; 95% CI: 0.49-0.78; MACE: HR, 0.87; 95% CI: 0.75-1.00). The study indicated no significant long-term effect of β-blocker use on risk of hospitalization for heart failure (HF), risk of recurrent MI, risk of stroke, and risk of repeat revascularization in post-MI patients (risk of hospitalization for HF: HR, 0.82; 95% CI: 0.58-1.16; risk of recurrent MI: HR, 0.93; 95% CI: 0.78-1.11; risk of stroke: HR, 0.94; 95% CI: 0.79-1.12; risk of repeat revascularization: HR, 0.91; 95% CI: 0.80-1.04).

CONCLUSIONS

The meta-analysis demonstrated significant long-term effects of β-blocker use on all-cause mortality, cardiovascular mortality, and risk of MACE in post-MI patients, whereas no significant long-term effect was shown on risk of hospitalization for HF, risk of recurrent MI, risk of stroke, and risk of repeat revascularization in post-MI patients.

The duration of beta-blocker therapy and outcomes in patients without heart failure or left ventricular systolic dysfunction after acute myocardial infarction: A multicenter prospective cohort study

Background

The duration of beta‐blocker therapy in patients without heart failure (HF) or left ventricular systolic dysfunction after acute myocardial infarction (AMI) is unclear.

Hypothesis

Continuous beta‐blocker therapy is associated with an improved prognosis.

Methods

This is a prospective, multicenter, cohort study. One thousand four hundred and eighty‐three patients eventually met the inclusion criteria. The study groups included the continuous beta‐blocker therapy group (lasted ≥6 months) and the discontinuous beta‐blocker therapy group (consisting of the no‐beta‐blocker therapy group and the beta‐blocker therapy <6 months group). The inverse probability treatment weighting was used to control confounding factors. The study tried to learn the role of continuous beta‐blocker therapy on outcomes. The median duration of follow‐up was 13.0 months. The primary outcomes were cardiac death and major adverse cardiovascular events (MACE). The secondary outcomes were all‐cause death, stroke, unstable angina, rehospitalization for HF, and recurrent myocardial infarction (MI).

Results

Compared with discontinuous beta‐blocker therapy, continuous beta‐blocker therapy was associated with a reduced risk of unstable angina, recurrent MI, and MACE (hazard ratio [HR]: 0.51; 95% CI: 0.32–0.82; p = 0.006); but this association was not available for cardiac death (HR: 0.57; 95% CI: 0.24–1.36; p = 0.206). When compared to the subgroups of no‐beta‐blocker therapy and beta‐blocker therapy <6 months, respectively, continuous beta‐blocker therapy was still observed to be associated with a reduced risk of unstable angina, recurrent MI, and MACE.

Conclusions

Continuous beta‐blocker therapy was associated with a reduced risk of unstable angina or recurrent MI or MACE in patients without HF or left ventricular systolic dysfunction after AMI.

Astragaloside IV Alleviates Infarction Induced Cardiomyocyte Injury by Improving Mitochondrial Morphology and Function

The protective effect of astragaloside IV (AS-IV) on myocardial injury after myocardial infarction has been reported. However, the underlying mechanism is still largely unknown. We established a myocardial infarction model in C57BL/6 mice and injected intraperitoneally with 10 mg/kg/d AS-IV for 4 weeks. The cardiac function, myocardial fibrosis, and angiogenesis were investigated by echocardiography, Masson's trichrome staining, and CD31 and smooth muscle actin staining, respectively. Cardiac mitochondrial morphology was visualized by transmission electron microscopy. Cardiac function, infarct size, vascular distribution, and mitochondrial morphology were significantly better in AS-IV-treated mice than in the myocardial infarction model mice. In vitro, a hypoxia-induced H9c2 cell model was established to observe cellular apoptosis and mitochondrial function. H9c2 cells transfected with silent information regulator 3 (Sirt3) targeting siRNA were assayed for Sirt3 expression and activity. Sirt3 silencing eliminated the beneficial effects of AS-IV and abrogated the inhibitory effect of AS-IV on mitochondrial division. These results suggest that AS-IV protects cardiomyocytes from hypoxic injury by maintaining mitochondrial homeostasis in a Sirt3-dependent manner.

One-Year Landmark Analysis of the Effect of Beta-Blocker Dose on Survival After Acute Myocardial Infarction

Background Although beta-blockers are recommended following myocardial infarction (MI), the benefits of long-term treatment have not been established. The study's aim was to evaluate beta-blocker efficacy by dose in 1-year post-MI survivors. Methods and Results The OBTAIN (Outcomes of Beta-Blocker Therapy After Myocardial Infarction) registry included 7057 patients with acute MI, with 6077 one-year survivors. For this landmark analysis, beta-blocker dose status was available in 3004 patients and analyzed by use (binary) and dose at 1 year after MI. Doses were classified as no beta-blocker and >0% to 12.5%, >12.5% to 25%, >25% to 50%, and >50% of target doses used in randomized clinical trials. Age was 63 to 64 years, and approximately two thirds were men. Median follow-up duration was 1.05 years (interquartile range, 0.98-1.22). When analyzed dichotomously, beta-blocker therapy was not associated with improved survival. When analyzed by dose, propensity score analysis showed significantly increased mortality in the no-beta-blocker group (hazard ratio,1.997; 95% CI, 1.118-3.568; P<0.02), the >0% to 12.5% group (hazard ratio, 1.817; 95% CI, 1.094-3.016; P<0.02), and the >25% to 50% group (hazard ratio, 1.764; 95% CI, 1.105-2.815; P<0.02), compared with the >12.5% to 25% dose group. The mortality in the full-dose group was not significantly higher (hazard ratio, 1.196; 95% CI, 0.687-2.083). In subgroup analyses, only history of congestive heart failure demonstrated significant interaction with beta-blocker effects on survival. Conclusions This analysis suggests that patients treated with >12.5% to 25% of the target dose used in prior randomized clinical trials beyond 1 year after MI may have enhanced survival compared with no beta-blocker and other beta-blocker doses. A new paradigm for post-MI beta-blocker therapy is needed that addresses which patients should be treated, for how long, and at what dose.

Prognostic impacts of β-blockers in acute coronary syndrome patients without heart failure treated by percutaneous coronary intervention

BACKGROUND

The use of β-blockers for acute coronary syndrome (ACS) patients without heart failure (HF) is controversial, and lacks of evidence in the era of reperfusion and intensive secondary preventions. This study aimed to investigate the prognostic impacts of β-blockers on patients with ACS but no HF treated by percutaneous coronary intervention (PCI).

METHODS

A total of 2397 consecutive patients with ACS but no HF treated by PCI were retrospectively recruited from January 2010 to June 2017. Univariable Cox regression was used to assess the prognostic impacts of β-blockers, followed by adjusted analysis, one-to-one propensity score matching (PSM), and inverse probability treatment weighting (IPTW) analysis, in order to control for systemic between-group differences. The primary outcome was all-cause death.

RESULTS

Among the included patients, 2060 (85.9%) were prescribed with β-blockers at discharge. The median follow-up time was 727 (433-2016) days, with 55 (2.3%) cases of all-cause death. Unadjusted analysis showed that the use of β-blockers was associated with lower risk of death (hazard ratio [HR]: 0.42, 95% confidence interval [CI]: 0.23-0.76, P = 0.004), which was sustained in adjusted analysis (HR: 0.53, 95% CI: 0.29-0.98, P = 0.044), PSM analysis (HR: 0.44, 95% CI: 0.20-0.96, P = 0.039) and IPTW analysis (HR: 0.49. 95% CI: 0.35-0.70, P < 0.001). Risk reduction was also seen in β-blocker users for cardiac death, but not for major adverse cardiovascular events.

CONCLUSIONS

The use of β-blockers was associated with reduced long-term mortality for ACS-PCI patients without HF.

Association between β-blocker dose and cardiovascular outcomes after myocardial infarction: insights from the SWEDEHEART registry

AIMS

Dose-dependent effects of β-blockers on survival and cardiovascular outcomes after myocardial infarction (MI) are not well understood. We investigated the long-term risk of cardiovascular events in patients with different doses of β-blockers after MI.

METHODS AND RESULTS

This was a nationwide observational study linking morbidity, mortality, socioeconomic, and medication data from Swedish national registries. Between 2006 and 2015, 97 575 unique patients with first-time MI were included. In total, 33 126 (33.9%) patients were discharged with ≥50% of the target β-blocker dose and 64 449 (66.1%) patients with <50% of the target β-blocker dose used in previous randomized trials. The primary composite endpoint was re-infarction or all-cause death within 1 year from discharge. Multivariable adjusted 1-year follow-up estimates using mixed effects Cox regression [HR (95% CI)] showed that patients treated with ≥50% of the target dose had a similar risk of the composite endpoint [1.03 (0.99-1.08)] and a somewhat higher risk when stroke, atrial fibrillation, or heart failure hospitalization were added to the composite endpoint [1.08 (1.04-1.12)], compared with patients on <50% of the target β-blocker dose. Results remained similar up to 5 years of follow-up and consistent across relevant patient subgroups, including patients who developed heart failure during the index hospitalization.

CONCLUSIONS

In contrast to doses of β-blockers used in previous trials, ≥50% of the target β-blocker dose was not associated with superior cardiovascular outcomes up to 5 years as compared with <50% of the target dose. Contemporary randomized clinical trials are needed to clarify the optimal dose of β-blockers after MI.

Long-term β-blocker therapy and clinical outcomes after acute myocardial infarction in patients without heart failure: nationwide cohort study

Aims

To investigate the association between long-term β-blocker therapy and clinical outcomes in patients without heart failure (HF) after acute myocardial infarction (AMI).

Method and results

Between 2010 and 2015, a total of 28 970 patients who underwent coronary revascularization for AMI with β-blocker prescription at hospital discharge and were event-free from death, recurrent myocardial infarction (MI), or HF for 1 year were enrolled from Korean nationwide medical insurance data. The primary outcome was all-cause death. The secondary outcomes were recurrent MI, hospitalization for new HF, and a composite of all-cause death, recurrent MI, or hospitalization for new HF. Outcomes were compared between β-blocker therapy for ≥1 year (N = 22 707) and β-blocker therapy for &lt;1 year (N = 6263) using landmark analysis at 1 year after index MI. Compared with patients receiving β-blocker therapy for &lt;1 year, those receiving β-blocker therapy for ≥1 year had significantly lower risks of all-cause death [adjusted hazard ratio (HR) 0.81; 95% confidence interval (CI) 0.72–0.91] and composite of all-cause death, recurrent MI, or hospitalization for new HF (adjusted HR 0.82; 95% CI 0.75–0.89), but not the risks of recurrent MI or hospitalization for new HF. The lower risk of all-cause death associated with persistent β-blocker therapy was observed beyond 2 years (adjusted HR 0.86; 95% CI 0.75–0.99) but not beyond 3 years (adjusted HR 0.87; 95% CI 0.73–1.03) after MI.

Conclusion

In this nationwide cohort, β-blocker therapy for ≥1 year after MI was associated with reduced all-cause death among patients with AMI without HF.