Endothelial function after ST-elevation myocardial infarction in patients with high levels of high-sensitivity CRP and Lp-PLA2: A substudy of the RESPONSE randomized trial

BACKGROUND

The combination of high levels of high-sensitive C-reactive protein (hs-CRP) and lipoprotein-associated phospholipase-A₂ (Lp-PLA₂) was recently shown to correlate with increased cardiovascular risk. Endothelial dysfunction is also known to be a risk factor for cardiovascular events.

AIM

To test among patients with previous ST-elevation myocardial infarction (STEMI) the hypothesis that high levels of both hs-CRP and Lp-PLA₂ may be associated with impaired endothelium-dependent vasodilatation.

METHODS

In this substudy of the RESPONSE randomized trial, we used reactive hyperemia peripheral artery tonometry (RH-PAT) 4 to 6weeks after STEMI and primary percutaneous coronary intervention (PPCI) to non-invasively assess endothelial function (RH-PAT index <1.67 identified endothelial dysfunction). Reliable measurements of RH-PAT, hs-CRP, and Lp-PLA₂ were obtained in 68 patients, who were classified as high-risk if levels of both hs-CRP and Lp-PLA₂ were in the upper tertile (≥3.84mg/L and >239μg/L, respectively).

RESULTS

Patients were 57.4±9.7years and 53 (77.9%) were men. 11 (16%) patients were classified as high-risk and 57 (84%) as low-to-intermediate-risk. The RH-PAT index was 1.68±0.22 in high-risk and 1.95±0.63 in low-to-intermediate-risk patients (p=0.17). Endothelial dysfunction was present in 8 (72.7%) high-risk and 26 (45.6%) low-to-intermediate-risk patients (p=0.09). Framingham risk score, NT-proBNP and fibrinogen levels were higher in high-risk patients (p≤0.03).

CONCLUSION

In this population of patients with recent STEMI and PPCI, we observed between patients with high hs-CRP and Lp-PLA levels and all other patients no more than numerical differences in endothelial function that did not reach a statistical significance. Nevertheless, further research in larger study populations may be warranted.

Evidence of myocardial scarring and microvascular obstruction on cardiac magnetic resonance imaging in a series of patients presenting with myocardial infarction without obstructed coronary arteries

Patients with acute chest pain, electrocardiographic ST-elevation and significant elevation of cardiac troponin but without obstructive coronary artery disease represent a diagnostic and therapeutic dilemma. Cardiac magnetic resonance imaging (CMR) can elucidate underlying alternative causes of troponin elevation including detection of (minor) myocardial infarction (MI) by identifying myocardial scarring as delayed enhancement. Of 77 patients, who were admitted between March 2009 and December 2012 with electrocardiographic (ECG) and biochemical evidence of acute MI without obstructive coronary artery disease, 45 patients underwent CMR that showed in 11/77 (14%) late gadolinium enhancement (LGE), compatible with myocardial scarring. We analyzed clinical, echocardiographic, and CMR data of these patients. Elevated troponin I levels were observed in all patients (median 1.3 ng/l, IQR 0.44-187) with median peak creatinine phosphokinase of 485 U/l (IQR 234-618). Echocardiographic wall motion abnormalities were detected in 8/11 (73%) patients; in 75% of these segments, ECG abnormalities were observed in corresponding leads. CMR detected LGE in the inferior (4/11), the inferolateral (5/11), the inferoseptal (2/11), the anterior (3/11), apical (3/11) and in the lateral segments (2/11). In addition, in all but two patients, these segments matched ECG abnormalities in corresponding leads. CMR identified microvascular obstruction in 4/11 (36%) patients. Patients with clinical, ECG, and biochemical signs of acute MI but unobstructed coronary arteries may have CMR-detectable myocardial scars. Information on myocardial scarring may help to make the diagnosis and draw therapeutic consequences. This case series underlines the value of contrast-enhanced CMR for myocardial tissue characterization.

Relationship between infarct tissue characteristics and left ventricular remodeling in patients with versus without early revascularization for acute myocardial infarction as assessed with contrast-enhanced cardiovascular magnetic resonance imaging

Left ventricular (LV) remodeling following myocardial infarction (MI) is the result of complex interactions between various factors, including presence or absence of early revascularization. The impact of early revascularization on the relationship between infarct tissue characteristics and LV remodeling is incompletely known. Therefore, we investigated in patients with versus without successful early revascularization for acute MI potential relations between infarct tissue characteristics and LV remodeling with contrast-enhanced (CE) cardiovascular magnetic resonance (CMR). Patients with versus without successful early revascularization underwent CE-CMR for tissue characterization and assessment of LV remodeling including end-diastolic and end-systolic volumes, LV ejection fraction, and wall motion score index (WMSI). CE-CMR images were analyzed for infarct tissue characteristics including core-, peri- and total-infarct size, transmural extent, and regional scar scores. In early revascularized patients (n = 46), a larger area of infarct tissue correlated significantly with larger LV dimensions and a more reduced LV function (r = 0.39-0.68; all P ≤ 0.01). Multivariate analyses identified peri-infarct size as the best predictor of LV remodeling parameters (R(2 )= 0.44-0.62). In patients without successful early revascularization (n = 47), there was no correlation between infarct area and remodeling parameters; only peri-infarct size versus WMSI (r = 0.33; P = 0.03) and transmural extent versus LVEF (r = -0.27; P = 0.07) tended to be related. A correlation between infarct tissue characteristics and LV remodeling was found only in patients with early successful revascularization. Peri-infarct size was found to be the best determinant of LV remodeling. Our findings stress the importance of taking into account infarct tissue characteristics and success of revascularization when LV remodeling is studied.