Undiagnosed cardiovascular risk factors including elevated lipoprotein(a) in patients with ischaemic heart disease.

Objectives: This study aims to investigate the prevalence of undiagnosed cardiovascular risk factors in patients with ischaemic heart disease (IHD). Methods: We assessed the prevalence of previously undiagnosed cardiovascular risk factors, including elevated lipoprotein(a) [Lp(a)], among consenting patients with IHD who were admitted to hospital. Clinical information, including dietary history, from patients with newly diagnosed IHD and known IHD were compared. Results: Of the 555 patients, 82.3% were males and 48.5% of Chinese ethnicity. Overall, 13.3% were newly diagnosed with hypertension, 14.8% with hypercholesterolemia, and 5% with type 2 diabetes (T2DM). Patients with newly diagnosed IHD, compared to those with known IHD, had a higher prevalence of new diagnoses of hypercholesterolemia (29.1% vs. 2.0%, p < 0.001), hypertension (24.5% vs. 3.4%, p < 0.001) and T2DM (7.3% vs. 3.1%, p = 0.023). Active smoking was prevalent in 28.3% of patients, and higher in newly diagnosed IHD (34.1% vs. 23.2%, p = 0.005). Elevated Lp(a) of ≥120 nmol/L was detected in 15.6% of all patients, none of whom were previously diagnosed. Dietary habits of >50% of patients in both groups did not meet national recommendations for fruits, vegetables, wholegrain and oily fish intake. However, patients with known IHD had a more regular omega-3 supplement intake (23.4% vs. 10.3%, p = 0.024). Conclusion: Increased detection efforts is necessary to diagnose chronic metabolic diseases (hypertension, hypercholesterolemia, T2DM) especially among patients at high risk for IHD. Cardiovascular risk factors, in particular elevated Lp(a), smoking, and suboptimal dietary intake in patients with IHD deserve further attention.

Clinicopathological correlates of out-of-hospital cardiac arrests.

Background: Sudden cardiac arrest with or without sudden cardiac death (SCD) represents a heterogeneous spectrum of underlying etiology but is often a catastrophic event. Despite improvements in pre-hospital response and post-resuscitation care, outcomes remain grim. Thus, we aim to evaluate the predictors of survival in out-of-hospital cardiac arrests (OHCAs) and describe autopsy findings of those with the uncertain cause of death (COD). Methods: This is a subgroup analysis of the Singapore cohort from the Pan Asian Resuscitation Outcome Study which studied 933 OHCAs admitted to two Singapore tertiary hospitals from April 2010 to May 2012. Results: Of the patients analysed, 30.2% (n = 282) had an initial return of spontaneous circulation (ROSC) at the emergency department, 18.0% (n = 168) had sustained ROSC with subsequent admission and 3.4% (n = 32) had survival to discharge. On multivariate analysis, an initial shockable rhythm, a witnessed event, prehospital defibrillation, and shorter time to hospital predicted ROSC as well as survival to discharge. A total of 163 (17.5%) autopsies were performed of which a cardiac etiology of SCD was noted in 92.1% (n = 151). Ischemic heart disease accounted for 54.3% (n = 89) of the autopsy cohort, with acute myocardial infarction (26.9%, n = 44) and myocarditis (3.7%, n = 6) rounding out the top three causes of demise. Conclusion: OHCA remains a clinical presentation that portends a poor prognosis. Of those with uncertain COD, cardiac etiology appears to predominate from autopsy study. Identification of prognostic factors will play an important role in improving individual-level and systemic-level variables to further optimize outcomes.

Treatment of Primary Aldosteronism and Reversal of Renin Suppression Improves Left Ventricular Systolic Function.

Introduction: Primary aldosteronism (PA) is associated with increased risk of cardiovascular events. However, treatment of PA has not been shown to improve left ventricular (LV) systolic function using the conventional assessment with LV ejection fraction (LVEF). We aim to use speckle-tracking echocardiography to assess for improvement in subclinical systolic function after treatment of PA. Methods: We prospectively recruited 57 patients with PA, who underwent 24-h ambulatory blood pressure (BP) measurements and echocardiography, including global longitudinal strain (GLS) assessment of left ventricle, at baseline and 12 months post-treatment. Results: At baseline, GLS was low in 14 of 50 (28.0%) patients. On multivariable analysis, GLS was associated with diastolic BP (P = 0.038) and glomerular filtration rate (P = 0.026). GLS improved post-surgery by -2.3, 95% CI: -3.9 to -0.6, P = 0.010, and post-medications by -1.3, 95% CI: -2.6 to 0.03, P = 0.089, whereas there were no changes in LVEF in either group. Improvement in GLS was independently correlated with baseline GLS (P < 0.001) and increase in plasma renin activity (P = 0.007). Patients with post-treatment plasma renin activity ≥1 ng/ml/h had improvements in GLS (P = 0.0019), whereas patients with persistently suppressed renin had no improvement. Post-adrenalectomy, there were also improvements in LV mass index (P = 0.012), left atrial volume index (P = 0.002), and mitral E/e' (P = 0.006), whereas it was not statistically significant in patients treated with medications. Conclusion: Treatment of hyperaldosteronism is effective in improving subclinical LV systolic dysfunction. Elevation of renin levels after treatment, which reflects adequate reversal of sodium overload state, is associated with better systolic function after treatment. Clinical Trial Registration: www.ClinicalTrials.gov, identifier: NCT03174847.

Asian Pacific Society of Cardiology Consensus Recommendations for Pre-participation Screening in Young Competitive Athletes.

Sports-related sudden cardiac death is a rare but devastating consequence of sports participation. Certain pathologies underlying sports-related sudden cardiac death could have been picked up pre-participation and the affected athletes advised on appropriate preventive measures and/or suitability for training or competition. However, mass screening efforts - especially in healthy young populations - are fraught with challenges, most notably the need to balance scarce medical resources and sustainability of such screening programmes, in healthcare systems that are already stretched. Given the rising trend of young sports participants across the Asia-Pacific region, the working group of the Asian Pacific Society of Cardiology (APSC) developed a sports classification system that incorporates dynamic and static components of various sports, with deliberate integration of sports events unique to the Asia-Pacific region. The APSC expert panel reviewed and appraised using the Grading of Recommendations Assessment, Development, and Evaluation system. Consensus recommendations were developed, which were then put to an online vote. Consensus was reached when 80% of votes for a recommendation were agree or neutral. The resulting statements described here provide guidance on the need for cardiovascular pre-participation screening for young competitive athletes based on the intensity of sports they engage in.

Improvement in quality of life and psychological symptoms after treatment for primary aldosteronism: Asian Cohort Study.

BACKGROUND: In addition to increased cardiovascular risk, patients with primary aldosteronism (PA) also suffer from impaired health-related quality of life (HRQoL) and psychological symptoms. We assessed for changes in HRQoL and depressive symptoms in a cohort of Asian patients with PA, after surgical and medical therapy. METHODS: Thirty-four patients with PA were prospectively recruited and completed questionnaires from 2017 to 2020. HRQoL was assessed using RAND-36 and EQ-5D-3L, and depressive symptoms were assessed using Beck Depression Inventory (BDI-II) at baseline, 6 months, and 1 year post-treatment. RESULTS: At 1 year post-treatment, significant improvement was observed in both physical and mental summative scores of RAND-36, +3.65, P = 0.023, and +3.41, P = 0.033, respectively, as well as four subscale domains (physical functioning, bodily pain, role emotional, and mental health). Significant improvement was also seen in EQ-5D dimension of anxiety/depression at 1 year post-treatment. Patients treated with surgery (n = 21) had significant improvement in EQ-5D index score post-treatment and better EQ-5D outcomes compared to the medical group (n = 13) at 1 year post-treatment. 37.9, 41.6 and 58.6% of patients had symptoms in the cognitive, affective and somatic domains of BDI-II, respectively. There was a significant improvement in the affective domain of BDI-II at 1 year post-treatment. CONCLUSION: Both surgical and medical therapy improve HRQoL and psychological symptoms in patients with PA, with surgery providing better outcomes. This highlights the importance of early diagnosis, accurate subtyping and appropriate treatment of PA.

Prognostic impact of stress echocardiography with discordant stress electrocardiography in patients with suspected coronary artery disease.

INTRODUCTION: During stress echocardiography, the echocardiologist routinely collects both echocardiographic images and stress electrocardiogram (ECG) concurrently. The managing physician faces a dilemma when the stress ECG and stress echocardiography results are discordant; for example, when a patient has negative stress echocardiography but positive stress ECG. We therefore sought to evaluate the prognostic value of stress echocardiography in relation to concordant or discordant stress ECG findings in our local Singapore setting, which has a well-defined Southeast Asian population. METHODS: This was a retrospective observational study of all patients who underwent stress echocardiography in 2012 at Changi General Hospital, Singapore. All study patients were followed up for 18 months via electronic medical records. RESULTS: There was no difference in the major adverse cardiovascular events (MACE) outcome of patients with normal stress echocardiography and normal stress ECG (reference group) as compared with patients with normal stress echocardiography but positive (discordant) stress ECG (odds ratio 2.02, 95% confidence interval 0.82‒4.98; p = 0.125). CONCLUSION: This study will help to reassure cardiologists that discordant results (negative stress echocardiography but positive stress ECG) do not portend a higher risk of MACE when compared to concordant results (i.e. both stress echocardiography and stress ECG are negative).

Elderly Asian Patients Have Lower Revascularisation Rates and Poorer Outcomes for ST-Elevation Myocardial Infarction Compared to Younger Patients.

INTRODUCTION: There is limited information on elderly patients presenting with ST- elevation myocardial infarction (STEMI). This study aimed to study the outcomes of elderly Asian patients with STEMI compared to younger patients. MATERIALS AND METHODS: The study utilised data from 2007 to 2012 from the Singapore Myocardial Infarction Registry, a mandatory national population-based registry. Elderly patients were defined as ≥80 years of age, middle-aged to old (MAO) patients were defined as 45-80 years of age and young patients were defined as ≤45 years of age. The primary outcome of the study was 1-year mortality and secondary outcomes included in-hospital complications and mortality. RESULTS: There were 12,409 STEMI patients with 1207 (9.7%) elderly patients, 10,093 (81.3%) MAO patients and 1109 (8.9%) young patients. Elderly patients had more cardiovascular risk factors and lower rates of total percutaneous coronary intervention (26.0% vs 72.4% vs 85.5%, respectively; P <0.0001) compared to MAO and young patients. They had higher 1-year mortality (60.6% vs 18.3% vs 4.1%, respectively; P <0.0001) when compared to MAO and young patients. CONCLUSION: Elderly patients with STEMI have poorer outcomes than MAO and young patients. This is potentially attributable to a myriad of factors including age, higher burden of comorbidities and a lesser likelihood of receiving revascularisation and guideline-recommended medical therapy.

A review of the safety and clinical utility of contrast echocardiography.

There are limitations to the sensitivity and specificity of conventional two-dimensional echocardiograms in making an accurate diagnosis in certain patient populations. This led to the development of specific contrast-enhancing agents with the following characteristics: small enough to cross the pulmonary capillary bed, remain stable throughout the length of the procedure, do not dissolve in blood, and rapidly cleared from the body with low toxicity. Unfortunately, the use of contrast echocardiography has not taken off as expected. The low take-up rate among clinicians can largely be attributed to the black box warning by the United States Food and Drug Administration in 2007, after the coincidental occurrence of four patient deaths and about 190 severe cardiopulmonary reactions shortly after contrast agent administration. In this article, we address the clinical safety of contrast agents, share our institution's experience in using it and elaborate on the clinical indications of contrast echocardiography.

Sex Differences in 1-Year Rehospitalization for Heart Failure and Myocardial Infarction After Primary Percutaneous Coronary Intervention.

It is unclear whether universal access to primary percutaneous coronary intervention (pPCI) may reduce sex differences in 1-year rehospitalization for heart failure (HF) and myocardial infarction (MI) after ST-elevation myocardial infarction (STEMI). We studied 7,597 consecutive STEMI patients (13.8% women, n = 1,045) who underwent pPCI from January 2007 to December 2013. Cox regression models adjusted for competing risk from death were used to assess sex differences in rehospitalization for HF and MI within 1 year from discharge. Compared with men, women were older (median age 67.6 vs 56.0 years, p < 0.001) with higher prevalence of co-morbidities and multivessel disease. Women had longer median door-to-balloon time (76 vs 66 minutes, p < 0.001) and were less likely to receive drug-eluting stents (19.5% vs 24.1%, p = 0.001). Of the medications prescribed at discharge, fewer women received aspirin (95.8% vs 97.6%, p = 0.002) and P2Y12 antagonists (97.6% vs 98.5%, p = 0.039), but there were no significant sex differences in other discharge medications. After adjusting for differences in baseline characteristics and treatment, sex differences in risk of rehospitalization for HF attenuated (hazard ratio [HR] 1.05, 95% confidence interval [CI] 0.79 to 1.40), but persisted for MI (HR 1.68, 95% CI 1.22 to 2.33), with greater disparity in patients aged ≥60 years (HR 1.83, 95% CI 1.18 to 2.85) than those aged <60 years (HR 1.45, 95% CI 0.84 to 2.50). In conclusion, in a setting of universal access to pPCI, the adjusted risk of 1-year rehospitalization for HF was similar in both sexes, but women had significantly higher adjusted risk of 1-year rehospitalization for MI, especially older women.

Cholesterol goal achievement and lipid-lowering therapy in patients with stable or acute coronary heart disease in Singapore: results from the Dyslipidemia International Study II.

INTRODUCTION: Dyslipidaemia is a major risk factor for coronary heart disease (CHD). There is a lack of data on the extent of lipid abnormalities and lipid-lowering therapy (LLT) in Singapore. METHODS: The Dyslipidemia International Study (DYSIS) II was a multinational observational study of patients with stable CHD and hospitalised patients with an acute coronary syndrome (ACS). A full lipid profile and use of LLT were documented at baseline, and for the ACS cohort, at four months post-hospitalisation. RESULTS: 325 patients were recruited from four sites in Singapore; 199 had stable CHD and 126 were hospitalised with an ACS. At baseline, 96.5% of the CHD cohort and 66.4% of the ACS cohort were being treated with LLT. In both cohorts, low-density lipoprotein cholesterol (LDL-C) levels were lower for the treated than the non-treated patients; accordingly, a higher proportion of patients met the LDL-C goal of < 70 mg/dL (CHD: 28.1% vs. 0%, p = 0.10; ACS: 20.2% vs. 0%, p < 0.01). By the four-month follow-up, a higher proportion of the ACS patients that were originally not treated with LLT had met the LDL-C goal (from 0% to 54.5%), correlating with the increased use of medication. However, there was negligible improvement in the patients who were treated prior to the ACS. CONCLUSION: Dyslipidaemia is a significant concern in Singapore, with few patients with stable or acute CHD meeting the recommended European Society of Cardiology/European Atherosclerosis Society goal. LLT was widely used but not optimised, indicating considerable scope for improved management of these very-high-risk patients.

Building a Longitudinal National Integrated Cardiovascular Database　- Lessons Learnt From SingCLOUD.

Background: Real world data on clinical outcomes and quality of care for patients with coronary artery disease (CAD) are fragmented. We describe the rationale and design of the Singapore Cardiovascular Longitudinal Outcomes Database (SingCLOUD). Methods and Results: We designed a health data grid to integrate clinical, administrative, laboratory, procedural, prescription and financial data from all public-funded hospitals and primary care clinics, which provide 80% of health care in Singapore. Here, we explain our approach to harmonize real-world data from diverse electronic medical and non-medical platforms to develop a robust and longitudinal dataset. We present pilot data on patients with myocardial infarction (MI) treated with percutaneous coronary intervention (PCI) between 2012 and 2014. The initial data set had 53,395 patients. Of these, 35,203 had CAD confirmed on coronary angiography, of whom 21,521 had PCI. Eventually, limiting to 2012-2014, 3,819 patients had MI with PCI, while 5,989 had MI. Compared with the quality improvement registry, Singapore Cardiac Data Bank, which had 189 fields for analysis, the SingCLOUD platform generated an additional 313 additional data fields, and was able to identify an additional 250 heart failure events, 664 major adverse cardiovascular events at 2 years, and low-density lipoprotein levels to 1 year for 3,747 patients. Conclusions: By integrating multiple incongruent data sources, SINGCLOUD enables in-depth analysis of real-world cardiovascular "big data".

First Medical Contact-to-Device Time and Heart Failure Outcomes Among Patients Undergoing Primary Percutaneous Coronary Intervention.

Background Expediting reperfusion during primary percutaneous coronary intervention is aimed at salvaging myocardium in ST-segment-elevation myocardial infarction. Few studies have examined the relation between reperfusion time and heart failure (HF) events. Methods and Results: We studied 7597 patients undergoing primary percutaneous coronary intervention from 2007 to 2013 in the Singapore Myocardial Infarct Registry, which captures HF at admission, postadmission in-hospital HF, and HF rehospitalization. We studied the relation of first medical contact to deployment of first device to achieve reperfusion (FTD) time with in-hospital HF events and HF rehospitalization, with mortality modeled as a competing risk. At the population level, median FTD time decreased from 91 minutes (interquartile range, 69-114) in 2007 to 58 minutes (45-75) in 2013 ( P=0.001), whereas mortality remained unchanged (in-hospital: range 5.3%-7.3%; P=0.190 and 1-year: range 7.8%-10.9%; P=0.505). HF at admission increased from 12.2% in 2007 to 18.4% in 2013, P=0.020, whereas postadmission in-hospital HF decreased from 12.8% in 2007 to 7.1% in 2013, P=0.030. HF rehospitalization increased from 1.2% in 2007 to 2.6% in 2013 ( P=0.003), for 30-day HF rehospitalization, and 3.8% in 2007 to 5.6% in 2013 ( P=0.037), for 1-year HF rehospitalization. At the individual level, among patients with HF at admission (N=1191), longer FTD time was associated with more 30-day HF rehospitalization (compared with ≤60 minutes, adjusted hazard ratio, 1.68 [0.73-3.86] for 60-90 minutes, 2.88 [1.19-6.92], for 90-120 minutes, and 2.84 [1.08-7.44] for >120 minutes). Longer FTD time was associated with a greater risk of postadmission in-hospital HF (compared with ≤60 minutes, adjusted hazard ratio, 1.18 [0.96-1.44] for 60-90 minutes, 1.59 [1.25-2.03] for 90-120 minutes, and 1.67 [1.26-2.21] for >120 minutes). Conclusions: Temporal reductions in FTD time were associated with decrease in postadmission in-hospital HF. Among patients presenting with HF at admission, delays in FTD beyond 90 minutes were associated with more 30-day HF rehospitalization.

Influence of Ethnicity, Age, and Time on Sex Disparities in Long-Term Cause-Specific Mortality After Acute Myocardial Infarction.

BACKGROUND: We examined the influence of sex, ethnicity, and time on competing cardiovascular and noncardiovascular causes of death following acute myocardial infarction in a multiethnic Asian cohort. METHODS AND RESULTS: For 12 years, we followed a prospective nationwide cohort of 15 151 patients (aged 22-101 years, median age 63 years; 72.3% male; 66.7% Chinese, 19.8% Malay, 13.5% Indian) who were hospitalized for acute myocardial infarction between 2000 and 2005. There were 6463 deaths (4534 cardiovascular, 1929 noncardiovascular). Compared with men, women had a higher risk of cardiovascular death (age-adjusted hazard ratio [HR] 1.3, 95% CI 1.2-1.4) but a similar risk of noncardiovascular death (HR 0.9, 95% CI 0.8-1.0). Sex differences in cardiovascular death varied by ethnicity, age, and time. Compared with Chinese women, Malay women had the greatest increased hazard of cardiovascular death (HR 1.4, 95% CI 1.2-1.6) and a marked imbalance in death due to heart failure or cardiomyopathy (HR 3.4 [95% CI 1.9-6.0] versus HR 1.5 [95% CI 0.6-3.6] for Indian women). Compared with same-age Malay men, Malay women aged 22 to 49 years had a 2.5-fold (95% CI 1.6-3.8) increased hazard of cardiovascular death. Sex disparities in cardiovascular death tapered over time, least among Chinese patients and most among Indian patients; the HR comparing cardiovascular death of Indian women and men decreased from 1.9 (95% CI 1.5-2.4) at 30 days to 0.9 (95% CI 0.5-1.6) at 10 years. CONCLUSION: Age, ethnicity, and time strongly influence the association between sex and specific cardiovascular causes of mortality, suggesting that health care policy to reduce sex disparities in acute myocardial infarction outcomes must consider the complex interplay of these 3 major modifying factors.

Comparison of Characteristics and Outcomes of Heart Failure Patients With Preserved Versus Reduced Ejection Fraction in a Multiethnic Southeast Asian Cohort.

There are few data comparing the patient characteristics and outcomes of heart failure with preserved ejection fraction (HFpEF) and heart failure with reduced EF (HFrEF) in Asian cohorts. We aimed to evaluate the prevalence, clinical characteristics, and 1-year outcomes of a well-defined Southeast Asian HFpEF cohort in comparison to an HFrEF cohort. We conducted a retrospective observational study of 1,978 patients discharged from Changi General Hospital, Singapore with a primary diagnosis of HF from 2009 to 2013. About 29% of discharges had HFpEF. Patients with HFpEF were more likely to be women, older age, and have a higher prevalence of hypertension. There were no significant differences in the absolute rates of 30-day outcomes between the 2 groups. The absolute rate of death at 1 year was similar in HFrEF and HFpEF at 17% and 15%, respectively (p = 0.3). After multivariate adjustment, there was no difference in the outcomes of the 2 groups. Atrial fibrillation at baseline was a predictor of death or HF hospitalization in HFpEF but not HFrEF (interaction p = 0.003). In conclusion, in this study of a Southeast Asian population with well-defined HF, we found that the clinical profile of patients with HF was similar to that in the West and 30-day and 1-year mortality and morbidity were not significantly different between cohorts.

Comparison of Long-Term Mortality of Patients Aged ≤40 Versus >40 Years With Acute Myocardial Infarction.

Young patients with acute myocardial infarction (MI) have a more favorable prognosis than older patients with MI. However, there are limited data comparing the prognosis of young patients with MI with young population controls. Comparison with an age-matched background population could unmask residual mortality risk in young patients with MI that would otherwise not be apparent when merely comparing the mortality risk of young and older patients with MI. We studied 15,151 patients with AMI from 2000 to 2005, of which 601 patients were ≤40 years (young MI). The relative survival ratio (RSR) was calculated as the ratio of the observed survival of patients with MI divided by the expected survival, estimated from the background population (n = 3,771,700) matched for age, gender, and follow-up year. An RSR of <1.0 or >1.0 indicates poorer or better survival, respectively, than the background population. The 12-year all-cause and cardiovascular mortality of young versus older patients was 12.8% versus 50.7% (p <0.001) and 9.2% versus 34.5% (p <0.001), respectively. The adjusted hazard ratio (95% confidence interval) for all-cause and cardiovascular mortality comparing young with older patients was 0.20 (0.16 to 0.27) and 0.27 (0.20 to 0.36), respectively. The RSR (95% confidence interval) of young and older patients was, respectively, 0.969 (0.950 to 0.980) and 0.804 (0.797 to 0.811) at 1 year, 0.942 (0.918 to 0.960) and 0.716 (0.707 to 0.726) at 5 years, and 0.908 (0.878 to 0.938) and 0.638 (0.620 to 0.654) at 9 years. In conclusion, despite a fivefold lower long-term mortality than older patients with MI, young patients with MI remain at significantly greater risk of long-term mortality than an age-matched background population.

Circadian Dependence of Infarct Size and Acute Heart Failure in ST Elevation Myocardial Infarction.

OBJECTIVES: There are conflicting data on the relationship between the time of symptom onset during the 24-hour cycle (circadian dependence) and infarct size in ST-elevation myocardial infarction (STEMI). Moreover, the impact of this circadian pattern of infarct size on clinical outcomes is unknown. We sought to study the circadian dependence of infarct size and its impact on clinical outcomes in STEMI. METHODS: We studied 6,710 consecutive patients hospitalized for STEMI from 2006 to 2009 in a tropical climate with non-varying day-night cycles. We categorized the time of symptom onset into four 6-hour intervals: midnight-6:00 A.M., 6:00 A.M.-noon, noon-6:00 P.M. and 6:00 P.M.-midnight. We used peak creatine kinase as a surrogate marker of infarct size. RESULTS: Midnight-6:00 A.M patients had the highest prevalence of diabetes mellitus (P = 0.03), more commonly presented with anterior MI (P = 0.03) and received percutaneous coronary intervention less frequently, as compared with other time intervals (P = 0.03). Adjusted mean peak creatine kinase was highest among midnight-6:00 A.M. patients and lowest among 6:00 A.M.-noon patients (2,590.8±2,839.1 IU/L and 2,336.3±2,386.6 IU/L, respectively, P = 0.04). Midnight-6:00 A.M patients were at greatest risk of acute heart failure (P<0.001), 30-day mortality (P = 0.03) and 1-year mortality (P = 0.03), while the converse was observed in 6:00 A.M.-noon patients. After adjusting for diabetes, infarct location and performance of percutaneous coronary intervention, circadian variations in acute heart failure incidence remained strongly significant (P = 0.001). CONCLUSION: We observed a circadian peak and nadir in infarct size during STEMI onset from midnight-6:00A.M and 6:00A.M.-noon respectively. The peak and nadir incidence of acute heart failure paralleled this circadian pattern. Differences in diabetes prevalence, infarct location and mechanical reperfusion may account partly for the observed circadian pattern of infarct size and acute heart failure.