Myocardial microstructure assessed by T1 mapping after on-pump and off-pump coronary artery bypass grafting

Background

The correlation between the release of cardiac biomarkers after revascularization, in the absence of late gadolinium enhancement (LGE) or myocardial edema, and the development of myocardial tissue damage remains unclear. This study sought to identify whether the release of biomarkers is associated with cardiac damage by assessing myocardial microstructure on T1 mapping after on-pump (ONCAB) and off-pump coronary artery bypass grafting (OPCAB).

Methods

Seventy-six patients with stable multivessel coronary artery disease (CAD) and preserved systolic ventricular function were included. T1 mapping, high-sensitive cardiac troponin I (cTnI), creatine kinase myocardial band (CK-MB) mass, and ventricular dimensions and function were measured before and after procedures.

Results

Of the 76 patients, 44 underwent OPCAB, and 32 ONCAB; 52 were men (68.4%), and the mean age was 63±8.5 years. In both OPCAB and ONCAB the native T1 values were similar before and after surgeries. An increase in extracellular volume (ECV) values after the procedures was observed, due to the decrease in hematocrit levels during the second cardiac resonance. However, the lambda partition coefficient showed no significant difference after the surgeries. The median peak release of cTnI and CK-MB were higher after ONCAB than after OPCAB [3.55 (2.12-4.9) vs. 2.19 (0.69-3.4) ng/mL, P=0.009 and 28.7 (18.2-55.4) vs. 14.3 (9.3-29.2) ng/mL, P=0.009, respectively]. Left ventricular ejection fraction (LVEF) was similar in both groups before and after surgery.

Conclusions

In the absence of documented myocardial infarction, T1 mapping did not identify structural tissue damage after surgical revascularization with or without cardiopulmonary bypass (CPB), despite the excessive release of cardiac biomarkers.

Association of Longitudinal Values of Glycated Hemoglobin With Cardiovascular Events in Patients With Type 2 Diabetes and Multivessel Coronary Artery Disease

IMPORTANCE

Glycated hemoglobin (HbA1c) values are used to guide glycemic control, but in patients with type 2 diabetes and multivessel coronary artery disease (CAD), the association of the longitudinal values of HbA1c with cardiovascular outcomes is unclear.

OBJECTIVE

To assess whether longitudinal variation of HbA1c is associated with cardiovascular events in long-term follow-up among patients with diabetes and multivessel CAD.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study included 888 patients with type 2 diabetes and multivessel CAD in the Medicine, Angioplasty, or Surgery Study (MASS) Registry of the Heart Institute of the University of São Paulo from January 2003 to December 2007. Data were analyzed from January 15, 2018, to October 15, 2019.

EXPOSURE

Longitudinal HbA1c values.

MAIN OUTCOMES AND MEASURES

The combined outcome of all-cause mortality, myocardial infarction, and ischemic stroke.

RESULTS

Of 888 patients with type 2 diabetes and multivessel CAD, 725 (81.6%; median [range] age, 62.4 [55.7-68.0] years; 467 [64.4%] men) had complete clinical and HbA1c information during a median (interquartile range) follow-up period of 10.0 (8.0-12.3) years, with a mean (SD) of 9.5 (3.8) HbA1c values for each patient. The composite end point of death, myocardial infarction, or ischemic stroke occurred in 262 patients (36.1%). A 1-point increase in the longitudinal value of HbA1c was significantly associated with a 14% higher risk of the combined end point of all-cause mortality, myocardial infarction, and ischemic stroke (hazard ratio, 1.14; 95% CI, 1.04-1.24; P = .002) in the unadjusted analysis. After adjusting for baseline factors (ie, age, sex, 2-vessel or 3-vessel CAD, initial CAD treatments, ejection fraction, and creatinine and low-density lipoprotein cholesterol levels), a 1-point increase in the longitudinal value of HbA1c was associated with a 22% higher risk of the combined end point (hazard ratio, 1.22; 95% CI, 1.12-1.35; P < .001).

CONCLUSIONS AND RELEVANCE

Longitudinal increase of HbA1c was independently associated with higher rates of cardiovascular events in patients with type 2 diabetes and multivessel CAD.

P598T1 mapping and myocardial extracellular volume assessed by cardiac magnetic resonance in diabetic patients with stable coronary artery disease

Background

T1 mapping is a quantitative technique of cardiac magnetic resonance (CMR) increasingly used for characterization of the myocardium. Type 2 diabetes mellitus (T2DM) may impact myocardial tissue structure, however studies that assessed this association using non-invasive methods have conflicting results.

Purpose

We sought to compare the tissue characteristics of the non-infarcted myocardium of patients with and without diabetes with multivessel CAD.

Methods

Patients with stable multivessel CAD and preserved left ventricular ejection fraction (LVEF), included in the MASS V trial, underwent contrast-enhanced CMR before revascularization procedures. Patients were stratified according to the T2DM diagnosis at baseline. Values of myocardial native T1, post-contrast T1 and extracellular volume fraction (ECV) were compared between diabetic and non-diabetic patients. Only myocardial tissue without late gadolinium enhancement were assessed.

Results

Of 155 patients studied, 67 (43%) were diabetic and 88 (57%) non-diabetic. Baseline characteristics were similiar between groups (age 70±10 vs 69±11; 69% vs 68% males; LVEF 65±13 vs 67±9). Mean Syntax score was 21.2±8.5 and 20.4±8.5 (p=0.52) in diabetic and non-diabetic, respectively. Myocardial native T1 values showed no diference in diabetic and non-diabetic (1013±67.9 vs 1015±61.4, p=0.72). However, in diabetic patients values of post-contrast T1 were significantly lower (482.2±43.8 vs 499.4±47.2, p=0.024) and ECV were higher (29.62±6.61 vs 27.08. ± 4.22, p=0.004). Multivariable analyses adjusted for age, sex, BMI, hypertension and Syntax score showed no differences in the results.

Figure1

Conclusion

In this study, T2DM was associated with higher ECV and lower post-contrast T1 values in the myocardial tissue. These findings suggest an increase in the myocardial intersticial matrix in patients with diabetes and stable multivessel CAD.

P1832Myocardial injury assessed by T1 mapping after on-pump and off-pump coronary artery bypass grafting. a pre-specified analysis of mass V trial

Background

Myocardial structural damage may occur during coronary artery bypass grafting (CABG) surgery and is identified by the significant release of cardiac biomarkers. However, the evidence of these structural myocardial changes after CABG by current imaging methods remains unknown. To evaluate myocardial structure, we used the T1 mapping of cardiac magnetic resonance (CMR) before and after on-pump and off-pump CABG.

Methods

Patients with multivessel coronary artery disease and preserved ventricular function were included and underwent on or off-pump CABG. CMR and T1 mapping were performed using the MOLLI technique (modified Look-Locker inversion-recovery). Values of native T1 and extracellular volume fraction (ECV) were compared before and after on and off-pump procedures.

Results

Of 110 eligible patients, 34 were excluded due to the presence of new late enhancement or edema. Of 76 patients remained, 32 (42%) underwent on-pump (Group A) and 44 (58%) off-pump CABG (Group B). All baseline characteristics were similar between groups, besides the Syntax Score that was higher in Group A (25 × 21, p=0.002). For group A, native T1 before and after procedures was 1013 ms (998–1043) and 1004 ms (793–1048), p=0.19, and ECV was 26.4 (23.9–27.6) and 31.2 (27.6–33.9), p<0.001. For group B, native T1 before and after procedures was 1015 ms (970–1044) and 992 ms (867–1051), p=0.003, and ECV 27.5 (25.3–29.9) and 30.3 (26.5–34.3), p=0.02. The comparison of native T1 difference before and after procedures between groups A and B was not significant (Delta T1 −9.8 (−102 to 51.8) × −25.4 (−119 to 51,2), p=0.87. However, the difference of ECV between groups was statistically significant (ECV Delta 3.8 (2.2 to 7.1) × 1.3 (−1.1 to 4.9), p=0.039, respectively, for groups A and B.

Figure 1

Conclusion

In this sample, T1 mapping identified significant myocardial structural changes in both surgical revascularization procedures. Additionally, a marked myocardial injury generated by ECV changes were observed after on-pump CABG.

P1835Application of SYNTAX score I, II and residual SYNTAX as predictors of long-term clinical outcomes after coronary artery bypass grafting

Background

The evaluation of coronary disease by SYNTAX score I (SSI) is used to grade coronary complexity. Following SSI, two other scores were developed: SYNTAX score II (SSII) and residual SYNTAX score (rSS). Nevertheless, there is still a lack of evidence about the prognostic significance of these scores among patients undergoing CABG.

Purpose

Our aim was to evaluate the relation of the SSI, SSII and rSS score with outcomes in a long-term follow-up after elective CABG.

Methods

This is a single center, registry-based study. Baseline SSI was calculated from patients undergoing CABG by interventional cardiologists. SSI results were considered as usual: <23, 23–32 and >32. SSII and rSRR were then calculated and categorized in tertiles: <21.4, 21.4–29.4 and >29.4 for SSII and 0, 1–5 and >5 for rSS. Primary outcome was a composite of overall death, myocardial infarction, additional revascularization, or stroke (MACCE).

Results

Data were obtained from 559 patients. Median follow-up was 6 years (IQR: 4.9–9.8) and 170 events were documented. The Kaplan-Meier curves (figure 1) showed significant differences of MACCE in higher SSI, SSII and rSS (p=0.039, 0.033, <0.001 respectively). After multivariate adjustment, rSS, ejection fraction (EF) and age were found to be independent predictors of MACCE (p<0.001, 0.034 and 0.006, respectively).

Figure 1

Conclusion

In this sample SSI, II and residual were associated with the occurrence of events. However, just the rSS remained an independent predictor of MACCE together with age and EF.