Right ventricular involvement in acute left ventricular myocardial infarction: prognostic implications of MRI findings. AJR Am J Roentgenol. 2010;194:592-598. [PMID: 20173133 DOI: 10.2214/ajr.09.2829]

Ischemic heart disease: comprehensive evaluation by cardiovascular magnetic resonance

Considerable technical advances over the past decade have increased the clinical application of cardiovascular magnetic resonance (CMR) imaging. A comprehensive CMR examination can accurately measure left and right ventricular size and function, identify the presence and extent of reversible versus irreversible myocardial injury, and detect inducible ischemia. Streamlined protocols allow such a CMR examination to be a time-efficient diagnostic tool in patients with coronary artery disease. Moreover, edema imaging with T2-weighted CMR allows the detection of acute coronary syndromes. In this review, we present the relevant CMR methods and discuss practical uses of CMR in acute and chronic ischemic heart disease.

Acute chest pain: the role of MR imaging and MR angiography

MR imaging (MRI) and MR angiography (MRA) have gained a high level of diagnostic accuracy in cardiovascular disease. MRI in cardiac disease has been established as the non-invasive standard of reference in many pathologies. However, in acute chest pain the situation is somewhat special since many of the patients presenting in the emergency department suffer from potentially life-threatening disease including acute coronary syndrome, pulmonary embolism, and acute aortic syndrome. Those patients need a fast and definitive evaluation under continuous monitoring of vital parameters. Due to those requirements MRI seems to be less suitable compared to X-ray coronary angiography and multislice computed tomography angiography (CTA). However, MRI allows for a comprehensive assessment of all clinically stable patients providing unique information on the cardiovascular system including ischemia, inflammation and function. Furthermore, MRI and MRA are considered the method of choice in patients with contraindications to CTA and for regular follow-up in known aortic disease. This review addresses specific features of MRI and MRA for different cardiovascular conditions presenting with acute chest pain.

Impact of hyperglycemia at admission in patients with acute ST-segment elevation myocardial infarction as assessed by contrast-enhanced MRI

BACKGROUND

Blood glucose level at admission in ST-segment elevation myocardial infarction (STEMI) is a predictor of heart failure and mortality. This study was performed to investigate the impact of hyperglycemia at admission in non-diabetic patients on infarct size, microvascular obstruction, and long-term outcome using contrast-enhanced magnetic resonance imaging (CMR) in patients with acute STEMI.

METHODS

One hundred and seven consecutive patients (84 males; mean age 59.4 years ± 11.3 years) with a first acute STEMI successfully treated by primary PCI were included. Admission hyperglycemia was defined as blood glucose above 7.8 mmol/l. CMR was performed 3.6 days ± 1.9 days after admission on a 1.5-tesla MR system. The imaging protocol included single-shot steady-state free precession (SSFP) cine sequences for assessing segmental and global left ventricular (LV) function and microvascular obstruction (MVO)/late gadolinium enhancement (LGE) imaging immediately and 10 min after the administration of 0.2 mmol gadodiamide/kg of body weight using an inversion-recovery SSFP (IR-SSFP) sequence. A receiver operating characteristics analysis was used to detect the best cut-off point of microvascular obstruction that predicted myocardial infarction and death during follow-up.

RESULTS

Of 107 patients, 37 (35%) had hyperglycemia on admission. Compared to normoglycemic patients, patients with admission hyperglycemia had a lower LV ejection fraction (38.6 ± 13.7% vs. 47.5 ± 12.2%, p < 0.001), greater ESV (88.8 ± 41.8 ml vs. 72.3 ml ± 35.1 ml, p = 0.01), greater infarct size (LGE% 21.1 ± 14.9% vs. 9.8 ± 8.7%, p < 0.001), and greater MVO (MVO% 9.6 ± 9.9% vs. 2.5 ± 4.3%, p < 0.001). Admission hyperglycemia was an independent predictor of the presence and extent of microvascular obstruction. Microvascular obstruction as a percentage of left ventricular mass was the only variable independently related to clinical outcome in a Cox proportional hazard model (Wald 18.78, HR 1.155, p < 0.001).

CONCLUSION

Hyperglycemia at admission in STEMI patients who are successfully treated by PCI is independently associated with the presence and extent of microvascular obstruction on contrast-enhanced CMR. Thus, microvascular obstruction as assessed by CMR may be a mechanism that relates admission hyperglycemia in acute STEMI to worse outcome.