Estimation of Infarct Size

Roberts R, Henry PD, Sobel BE. An improved basis for enzymatic estimation of infarct size. Circulation 1975 52 743-54. 

Sobel BE, Bresnahan GF, Shell WE, Yoder RD. Estimation of infarct size in man and its relation to prognosis. Circulation 1972 46 640-648. 

Thus, overall in the three trials that assessed the potential benefit of a strategy in which thrombolysis was combined with PCI in the treatment of acute STEMI, no evidence of clinical benefit attributable to prompt PCI following thrombolysis was apparent. By contrast, complications occurred at an increased frequency. None of the trials had been powered to assess an impact on mortality. However, the lack of improvement in left ventricular ejection fraction, enzymatic estimate of infarct size, or the incidence of reinfarction was deemed to be discouraging. Moreover, the lack of apparent benefit was associated with an increased risk of bleeding. 

Tanaka H, Abe S, Yamashita T, Arima S, Saigo M, Nakao S, et al. Serum levels of cardiac troponin I and troponin T in estimating myocardial infarct size soon after reperfusion. Cor Art Dis 1997 8 433-9. 

Hindman NB, Schocken DD, Widmann M et al. Evaluation of a QRS scoring system for estimating myocardial infarct size. V specificity and method of application of the complete... 

Selvester RH, Wagner GS, Hindman NB. The Selvester QRS scoring system for estimating myocardial infarction size the development and application of the system. Arch Intern Med 1985 145 1877. 

Kurmukov AG, Ermishina OA (1986) Influence of ecdysterone on the size of the necrotic zone after experimental myocardial infarction. In Otsenka Razmera i Taktika Lecheniya Infarkta Miokarda (Estimation of the size, and methods for treating, myocardial infarction), Tomsk, pp 62-63 (in Russian)... 

TIA-related infarctions on DWI are often very small (Ay et al. 2002 Kidwell et al. 1999 Rovira et al. 2002). As mentioned before, 96% of infarctions on DWI are smaller than 1 ml in volume. The mean infarction load (total volume of all acute infarctions if there are multiple) on DWI has been reported to be 1.5+1.8 ml (Ay et al. 2005). An infarction load of less than 1.8 ml is associated with reversible clinical deficit within 24 h with 79% sensitivity and 78% specificity. Two other DWI studies have produced similar results. Ay et al. (2002) found that the infarction size was less than 15 mm in diameter in 85% of 27 TIA patients with infarction identified by DWI, of which 83% were punctate (< 5 mm). Rovira et al. (2002) estimated TIA-related infarctions range from 2 to 40 mm in diameter (mean, 15 mm). Figures 12.3 and 12.4 present examples of small hyperintense lesions on DWI that represent the remnants or footprints of a recent ischemia. 

Nowadays, CMR has demonstrated great accuracy in estimating infarcted mass (Horacek et al., 2006 Moon et al, 2004) (Figures 9.1 and 9.2), which makes this technique the gold standard for the quantification of infarction mass. However, recently, Engblom (2006) has reported that in patients with first time reperfused MI the QRS score is significantly related to both MI size and transmural-ity. Also, recently, it has been published that high QRS Selvester score is an independent predictor of incomplete ST recovery and complications in STE-ACS treated with primary PCI (Uyarel et al., 2006). 

Different score systems have been developed to estimate, following a Q-wave infarction, its size and ventricular function (Hinohara et al., 1984 Pahlm et al., 1998 Pahneri et al., 1982 Selvester, Wagner and Hindman, 1985 Wagner and Hino-hara, 1984). However, currently CE-CMR is the gold standard for measurement and characterisation of infarcted area (see Quantification of the infarcted area ). 

Pahlm O, Chaitman B, Rautaharju P, Selvester R, Wagner G. Comparison of the various electrocardiographic scoring codes for estimating anatomically documented sizes of single and multiple infarcts of the left ventricle. Am J Cardiol 1998 81 809. 

Nl. Nagai, R., Chiu, C. C Yamaoki, K., Ohuchi, Y., Ueda, S., Imataka, K., and Yazaki, Y., Evaluation of methods for estimating infarct size by myosin LC2 Comparison with cardiac enzymes. Am. J. Physiol 245, H413-H419 (1983). 

In the clinical setting, diffusion-weighted imaging provides the most accurate and reliable estimate of the core infarct. However, MRI is limited by the lack of widespread availability in the emergent setting. Therefore, CT-based methods have been used to measure the infarct core. Studies utilizing these techniques have provided further evidence for the role of core infarct size in determining treatment response. 

The estimates used to create the composite endpoint were based on previous clinical trials of STEMI [death (4-6%), cardiogenic shock (5-7%), late resuscitated VF (0.5-2%) and rehospitalization for HE (4-7%)], acknowledging some overlap for infarct size-related complications. Risk groups were divided into low, medium, and high based... 

Horacek BM, Warren JW, Albano A et al. Development of an automated Selvester Scoring System for estimating the size of myocardial infarction from the electrocardiogram. J Electrocardiol 2006 39(2) 162-8. 

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