The impact of infarct type on the reliability of early oral glucose tolerance testing in patients with myocardial infarction

Hyperglycemia newly detected by glycated hemoglobin affects all-cause mortality in coronary artery disease patients: a retrospective cohort study

AIMS

We aim to assess the relationship between hyperglycemia and long-term prognosis in CAD patients without known diabetes.

METHODS

In this retrospective observational study, we enrolled 11,384 CAD patients without known diabetes. Newly detected diabetes was defined as HbA1c ≥ 6.5 %, and prediabetes was defined as HbA1c ranging from 5.7 to 6.4 %.The association between hyperglycemia and long-term all-cause mortality was examined using Cox proportional hazards regression analysis.

RESULTS

According to HbA1c level, 8207 (72.1 %) patients had hyperglycemia, including 13.0 % with diabetes and 59.1 % with prediabetes. During a median follow-up of 4.9 years, 1157(10.2 %) patients died. Compared with normoglycemia, hyperglycemia was associated with increased risk for long-term mortality (adjusted hazard ratio for diabetes and prediabetes: 1.23 [95 % confidence interval (CI): 1.00 to 1.51] and 1.17 [95 % CI: 1.01 to 1.36], respectively).

CONCLUSIONS

Hyperglycemia detected by HbA1c was common in CAD patients without known diabetes and was associated with increased long-term mortality. It is necessary to routinely use HbA1c to assess glucose metabolic status in CAD patients and treat hyperglycemia as early as possible to reduce the risk of adverse outcomes.

Postload glucose spike but not fasting glucose determines prognosis after myocardial infarction in patients without known or newly diagnosed diabetes

BACKGROUND

The effect of postload glucose spikes (PGS), the difference between 2 hour post-load plasma glucose (2hPLPG) and fasting plasma glucose (FPG), on post-myocardial infarction (post-MI) prognosis in nondiabetic patients is unexplored.

METHODS

This is a retrospective cohort analysis of 847 nondiabetic post-MI survivors who underwent a predischarge oral glucose tolerance test (median PGS: 2.4 mmol/L). Patients were divided into the unmatched groups 1 and 2 (PGS ≤ and > 2.4 mmol/L) and the propensity score-matched groups 1M and 2M (355 pairs assembled from the overall cohort), and these groups were compared. Major adverse cardiac events (MACE: death and nonfatal reinfarction) were recorded during follow-up (median: 3.4 years). Event-free survival was compared by the Kaplan-Meier method. Multivariate Cox proportional hazards regression determined the predictors of MACE. C-statistics (change in area under the curve, δAUC), continuous net reclassification improvement (NRI^>0 ), and integrated discrimination improvement (IDI) were used to compare models.

RESULTS

The number of MACE was higher in groups 2 (27.3% vs 14.2%, P < .001) and 2M (24.5% vs 15.5%, P < .001). Event-free survival was worse in groups 2 (hazard ratio [HR] 2.01; 95% CI, 1.49-2.71; P < .001) and 2M (HR 1.63; 95% CI, 1.17-2.27; P = .004). PGS independently predicted MACE-free survival in the whole (HR 1.16; 95% CI, 1.06-1.26; P = .002) and matched cohort (HR 1.12; 95% CI, 1.02-1.24; P = .021). PGS, but not FPG or 2hPPG, improved the predictive performance of the base model (δAUC 0.013, P = .046), with greater improvement seen when PGS was added and compared to 2hPPG (δAUC 0.005, P = .034; NRI^>0 0.2107, P = .013; IDI 0.0042, P = .046).

CONCLUSION

PGS is a better predictor of post-MI prognosis than 2hPPG in nondiabetic patients.

Two-Hour Post-Load Plasma Glucose, a Biomarker to Improve the GRACE Score in Patients without Known Diabetes

OBJECTIVE

To assess improvement in predictive performance of Global Registry of Acute Coronary Events risk score (GRS) by addition of a glucose matrix.

METHODS

1,056 acute coronary syndrome (ACS) survivors without known diabetes had pre-discharge fasting (FPG) and 2-h post-load plasma glucose (2h-PG) measured. GRS was calculated. Major adverse cardiac events (MACE; death and non-fatal myocardial infarction) were recorded during follow-up. Cox proportional hazard regression predicted event-free survival. Likelihood ratio test, Akaike's information criteria, continuous net reclassification index (NRI>0), and integrated discrimination improvement (IDI) were used to test the additional prognostic value of glycaemic indices over GRS.

RESULTS

During a median follow-up of 36.5 months, 211 MACEs (20.0%), 96 deaths (9.1%), and 115 non-fatal re-infarctions (10.9%), occurred. 2h-PG, but not FPG, independently predicted MACE-free survival at all time points (HR 1.08, 95% CI 1.03-1.13, p = 0.002, at 3 years). Risk of MACE increased by 8-11% with every 1 mmol/L rise in 2h-PG. 2h-PG significantly improved the prognostic models containing GRS. Models containing GRS and 2h-PG yielded lowest corrected Akaike's information criteria compared to that with only GRS. 2h-PG, but not FPG, improved NRI>0 (NRI>0 0.169, p = 0.028 at 3 years) and IDI (IDI of 0.66%, p = 0.018 at 3 years) significantly at all time points during the follow-up.

CONCLUSIONS

2h-PG, but not FPG, improves performance of GRS-containing models in predicting post-ACS prognosis in the short to medium term.

Newly diagnosed abnormal glucose tolerance determines post-MI prognosis in patients with hospital related hyperglycaemia but without known diabetes

AIMS

Investigate if abnormal glucose tolerance (AGT) affects post-myocardial infarction (MI) prognosis in patients with hospital-related hyperglycaemia (HRH) but without known diabetes mellitus (KDM).

METHODS

Post-MI survivors without KDM underwent pre-discharge oral glucose tolerance test. Cardiovascular death and non-fatal re-infarction (MACE) were recorded. We compare the ability of admission (APG), fasting (FPG) and 2 h post-load (2 h-PG) plasma glucose to predict MACE in patients with (HRH) and without HRH (NoHRH).

RESULTS

50.2% and 73% of NoHRH and HRH had AGT respectively. MACE occurred in 19.5% and 18.1% in HRH and NoHRH groups. MACE-free survival was lower in patient with AGT in both groups (NoHRH: HR 1.82, 95% CI 1.19-2.78, p = 0.005; HRH: HR 2.48, 95% CI 1.24-4.96, p = 0.010). AGT predicted MACE-free survival (NoHRH: HR 1.60, 95% CI 1.02-2.51, p = 0.042; HRH: HR 3.09, 95% CI 1.07-8.94, p = 0.037). 2 h-PG, but not FPG or APG, independently predicted MACE free survival (NoHRH: HR 1.17, 95% CI 1.07-1.27, p ≤0.001 and HRH: HR 1.18, 95% CI 1.03-1.37, p = 0.020). Addition of AGT and 2 h-PG, not FPG or APG, improved net reclassification of events in both groups.

CONCLUSION

Post-MI prognosis is worse with AGT irrespective of presence of HRH. 2 h-PG, predicts prognosis in HRH and NoHRH groups.

Adjustment of the GRACE score by 2-hour post-load glucose improves prediction of long-term major adverse cardiac events in acute coronary syndrome in patients without known diabetes

Aims

Global Registry of Acute Coronary Events (GRACE) risk score (GRS), a powerful predictor of prognosis after acute coronary event (ACE), does not include a glucometabolic measure. We investigate whether 2 h post-load plasma glucose (2h-PG) could improve GRS based prognostic models in ACE patients without known diabetes mellitus (DM).

Methods and results

A retrospective cohort study of 1056 ACE survivors without known DM who had fasting plasma glucose (FPG) and 2h-PG measured pre-discharge. Death and non-fatal myocardial infarction were recorded as major adverse cardiac events (MACE) during follow-up. GRS for discharge to 6 months was calculated. Cox proportional-hazards regression was used to identify predictors of event free survival. The predictive value of 2h-PG alone and combined with GRS was estimated using likelihood ratio test, Akaike's information criteria, continuous net reclassification improvement (NRI>0), and integrated discrimination improvement (IDI). During 40.8 months follow-up 235 MACEs (22.3%) occurred, more frequently in the upper 2h-PG quartiles. Two-hour PG, but not FPG, adjusted for GRS independently predicted MACE (hazard ratio 1.091, 95% confidence interval 1.043-1.142; P = 0.0002). likelihood ratio test showed that 2h-PG significantly improved the prognostic models including GRS (χ2 = 20.56, 1 df; P = 0.000). Models containing GRS and 2h-PG yielded lowest corrected Akaike's information criteria, compared to that with only GRS. 2h-PG, when added to GRS, improved net reclassification significantly (NRIe>0 6.4%, NRIne>0 24%, NRI>0 0.176; P = 0.017 at final follow-up). Two-hour PG, improved integrated discrimination of models containing GRS (IDI of 0.87%, P = 0.008 at final follow-up).

Conclusion

Two-hour PG, but not FPG, is an independent predictor of adverse outcome after ACE even after adjusting for the GRS. Two-hour PG, but not FPG, improves the predictability of prognostic models containing GRS.

Two-hour post-challenge glucose is a better predictor of adverse outcome after myocardial infarction than fasting or admission glucose in patients without diabetes

AIMS

We evaluate prevalence of new abnormal glucose tolerance (AGT) in post-MI survivors without known diabetes (DM) if guidelines are followed and compare the ability of admission (APG), fasting (FPG) and 2-h post-load plasma glucose (2h-PG) to predict prognosis.

METHODS

A total of 674 patients were followed up for 4 years for incidence of major adverse cardiovascular events (MACE) of cardiovascular death, non-fatal re-infarction or non-haemorrhagic stroke. Ability of models including APG, FPG and 2h-PG to predict MACE was compared.

RESULTS

Of the total, 93-96% of impaired glucose tolerance and 64-75% of DM would be missed with current guidelines. MACE was higher in the upper quartiles of 2h-PG. When 2h-PG and FPG were included simultaneously in models, only 2h-PG predicted MACE (HR 1.12, CI 1.04-1.20, p = 0.0012), all cause mortality (HR 1.17, CI 1.05-1.30, p = 0.0039), cardiovascular mortality (HR 1.17, CI 1.02-1.33, p = 0.0205) and non-fatal MI (HR 1.10, CI 1.01-1.20, p = 0.0291). Adding 2h-PG significantly improved ability of models including FPG (χ² = 16.01, df = 1, p = 0.0001) or FPG and APG (χ² = 17.36, df = 1, p = 0.000) to predict MACE. Model including 2h-PG only had the lowest Akaike's information criteria and highest Akaike weights suggesting that this was the best in predicting events. Adding 2h-PG to models including FPG or APG with other co-variates yielded continuous net reclassification improvement (NRI) of 0.22 (p = 0.026) and 0.27 (p = 0.005) and categorical NRI of 0.09 (p = 0.032) and 0.12 (p = 0.014), respectively. Adding 2 h-PG to models including only FPG, only APG and both yielded integrated discrimination improvement of 0.012 (p = 0.015), 0.022 (p = 0.001) and 0.013 (p = 0.014), respectively.

CONCLUSIONS

AGT is under-diagnosed on current guidelines. 2h-PG is a better predictor of prognosis compared to APG and FPG.

HbA1c screening for new onset diabetes following acute coronary syndrome: is it a worthwhile test in clinical practice?

Background

Diabetes and pre-diabetes are prevalent in acute coronary syndrome (ACS) and relate to adverse outcomes. This study used HbA_1c to screen for degrees of glucose intolerance amongst patients without known diabetes presenting with ACS.

Methods

Over a 1-year period (June 2014–2015) consecutive patients admitted to a single centre cardiology unit with an initial diagnosis of ACS without prior diabetes diagnosis were electronically referred to our diabetes team. Patients were screened for the presence of diabetes by use of an initial HbA_1c blood test on day 2 or 3 post admission. If abnormal (≥42 mmol/mol; ≥6.0%), patients were invited for a repeat HbA_1c at 2 weeks, and if an intermediate result (42–47 mmol/mol; 6.0–6.4%), for an oral glucose tolerance test (OGTT) at 3 months. Patients were diagnosed with Type 2 diabetes if the repeat HbA_1c result was high (≥48 mmol/mol; ≥6.5%) or the OGTT at 3 months confirmed the diagnosis. Other data collected included baseline demographics, risk factors and any history of cardiovascular disease. All patients with ACS were stratified according to the diagnosis and subsequent management.

Results

We screened 399 patients in total. The mean age was 65 ± 14 years, 268 (67%) were men, 290 (73%) were Caucasian, 95 (24%) were South Asian and 14 (4%) were Afro-Caribbean ethnicity. Of all patients, 57 (14.3%) were diagnosed as pre-diabetes and 43 (10.8%) newly diagnosed diabetes. During the study 28 (7%) patients could not be classified; 6 (1.5%) patients died during the study and 22 (5.5%) patients were missing either initial or repeat HbA_1c and were subsequently lost to follow up. Of the baseline variables assessed, there were significantly more patients of South Asian ethnicity in the diabetes group compared to the normal group (42 vs 20%; p = 0.003). There was no difference in detection rates in patients with more severe ACS requiring percutaneous or cardiac surgical intervention.

Conclusions

The use of a simple HbA_1c screening method in clinical practice can detect new onset diabetes in approximately 1 in 10 high-risk post ACS patients.

Diabetes for Cardiologists: Practical Issues in Diagnosis and Management

Diabetes mellitus (DM), a chronic metabolic disease characterized by hyperglycemia, is a profound cardiovascular (CV) risk factor. It compounds the effects of all other risk factors, leads to premature micro- and macrovascular disease, facilitates development of heart failure, worsens the clinical course of all CV diseases, and shortens life expectancy. Established DM, unrecognized DM, and dysglycemia that may progress to DM are all commonly present at the time of presentation of overt CV disease. Thus, CV specialists and trainees frequently treat patients with dysglycemia. The traditional and proven role of cardiologists in reducing the risk of macrovascular events in this population is through aggressive lipid and blood pressure treatment. However, a more proactive role in the detection and management of DM is likely to become increasingly important as the prevalence continues to increase and therapies continue to improve. The latter include antihyperglycemic therapies with proven cardiovascular safety profiles and CV event reduction properties not yet fully elucidated and not necessarily related to glycemic control. Accordingly, the purpose of this article is to (1) expand the interest of cardiologists in earlier stages of the natural history of DM, when prevention or early detection might help achieve greatest benefit; (2) highlight principles of optimal glycemic management, with an emphasis on add-on choices showing promising reduction of CV events and lacking CV adverse effects; and (3) encourage cardiologists to become proactive partners in the multidisciplinary care needed to ensure optimal lifelong vascular health in patients with, or who are at risk of, DM.

Impaired Glucose Tolerance or Newly Diagnosed Diabetes Mellitus Diagnosed during Admission Adversely Affects Prognosis after Myocardial Infarction: An Observational Study

Objective

To investigate the prognostic effect of newly diagnosed diabetes mellitus (NDM) and impaired glucose tolerance (IGT) post myocardial infarction (MI).

Research Design and Methods

Retrospective cohort study of 768 patients without preexisting diabetes mellitus post-MI at one centre in Yorkshire between November 2005 and October 2008. Patients were categorised as normal glucose tolerance (NGT n = 337), IGT (n = 279) and NDM (n = 152) on pre- discharge oral glucose tolerance test (OGTT). Primary end-point was the first occurrence of major adverse cardiovascular events (MACE) including cardiovascular death, non-fatal MI, severe heart failure (HF) or non-haemorrhagic stroke. Secondary end-points were all cause mortality and individual components of MACE.

Results

Prevalence of NGT, impaired fasting glucose (IFG), IGT and NDM changed from 90%, 6%, 0% and 4% on fasting plasma glucose (FPG) to 43%, 1%, 36% and 20% respectively after OGTT. 102 deaths from all causes (79 as first events of which 46 were cardiovascular), 95 non fatal MI, 18 HF and 9 non haemorrhagic strokes occurred during 47.2 ± 9.4 months follow up. Event free survival was lower in IGT and NDM groups. IGT (HR 1.54, 95% CI: 1.06–2.24, p = 0.024) and NDM (HR 2.15, 95% CI: 1.42–3.24, p = 0.003) independently predicted MACE free survival. IGT and NDM also independently predicted incidence of MACE. NDM but not IGT increased the risk of secondary end-points.

Conclusion

Presence of IGT and NDM in patients presenting post-MI, identified using OGTT, is associated with increased incidence of MACE and is associated with adverse outcomes despite adequate secondary prevention.

Clinical significance of glycated hemoglobin in the acute phase of ST elevation myocardial infarction

In population-based studies, including diabetic and nondiabetic cohorts, glycated hemoglobin A1c (HbA1c) has been reported as an independent predictor of all-cause and cardiovascular disease mortality. Data on the prognostic role of HbA1c in patients with acute myocardial infarction (MI) are not univocal since they stem from studies which mainly differ in patients' selection criteria, therapy (thrombolysis vs mechanical revascularization) and number consistency. The present review is focused on available evidence on the prognostic significance of HbA1c measured in the acute phase in patients with ST-elevation myocardial infarction (STEMI) submitted to primary percutaneous coronary intervention (PCI). We furthermore highlighted the role of HbA1c as a screening tool for glucose intolerance in patients with STEMI. According to available evidence, in contemporary cohorts of STEMI patients submitted to mechanical revascularization, HbA1c does not seem to be associated with short and long term mortality rates. However, HbA1c may represent a screening tool for glucose intolerance from the early phase on in STEMI patients. On a pragmatic ground, an HbA1c test has several advantages over fasting plasma glucose or an oral glucose tolerance test in an acute setting. The test can be performed in the non-fasting state and reflects average glucose concentration over the preceding 2-3 mo. We therefore proposed an algorithm based on pragmatic grounds which could be applied in STEMI patients without known diabetes in order to detect glucose intolerance abnormalities from the early phase. The main advantage of this algorithm is that it may help in tailoring the follow-up program, by helping in identifying patients at risk for the development of glucose intolerance after MI. Further validation of this algorithm in prospective studies may be required in the contemporary STEMI population to resolve some of these uncertainties around HbA1c screening cutoff points.

A simple strategy for screening for glucose intolerance, using glycated haemoglobin, in individuals admitted with acute coronary syndrome

Glucose intolerance is common but often remains undiagnosed and untreated in people with acute coronary syndrome. The best approach to screening for glucose intolerance post-acute coronary syndrome remains debated. The World Health Organization has recently advocated the use of HbA(1c) in diagnosing Type 2 diabetes. A screening strategy using HbA(1c) as the preferred test would be pragmatic and improve early detection and management of glucose intolerance in acute coronary care practice. In this commentary, we discuss the relevant literature and guidelines in this area and propose a simple and pragmatic algorithm based on the use of HbA(1c) to screen for glucose intolerance during and after admission with acute coronary syndrome.