Sudden Disappearance of Electrocardiographic Pattern of Anteroseptal Myocardial Infarction

Sudden Disappearance of Electrocardiographic Pattern of Anteroseptal Myocardial Infarction *

sudden disappearance of the pattern of anteroseptal myocardial infarction in the ECG, resulting from a superimposed acute posterior myocardial infarction. CASE REPORT

Result of Superimposed Acute Posterior Myocardial Infarction Kuuhuun Wang, M.D.; Marvin S. Segal, M.D.; and Patrick C.]. Ward, M.D.

In a 76-year-old man an electrocardiographic pattern of acute anteroseptal myocardial infarction disappeared suddenly. At necropsy, a more recent posterior myocardial infarct was found, in addition to an acute anteroseptal infarct. "Normalization" of the electrocardiogram from the pattern of anteroseptal myocardial infarction in this case resulted from the loss of opposing electromotive forces in the posterior wall because of posterior infarction.

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ath ologic Q waves in the elec tro card iogram resultin g from a myocardial inf arction may regress or di sappear at a later date .\-; This cas e report illustrates

°From the Departments of Medicine and Pathology, Mt. Sinai Hospital and the Univers ity of Minnesota Medical School, Minneapolis. Reprint requests: Dr. Wang, Mt . Sinai Hospital , Minneapolis 55404

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FIGURE 1. Serial ECGs and serum levels of cardiac enzymes. Leads aVR, aVL, and aVF are not included for lack of space. P waves are included only in lead V J and demon strate prolonged P-R intervals. Tracings on Nov 15 and 16 (AM) show new development of complete right bundle-branch block and pathologic Q waves in leads VI to V4 , indicating anteroseptal myocardial infarction. Tracings on Nov 16 (PM) and 18 show disappearance of right bundle-branch block and reappearance of R waves in leads V~ to V4. These tracings are no longer diagnostic for anteroseptal myocardial infarction. Cardiac enzyme concentrations are elevated on Nov 17,18, and 19. (SGOT, serum glutamic oxaloacetic transaminase; and LDH, lactic dehydrogenase. )

402 WANG, SEGAL, WARD

A 76-year-old white man with hypertension and angina pectoris compla ined of chest pain on Nov 15, 1974, one day after a transurethral resection of a benign hypertrophic prostate gland . The ECG taken on Nov 15 (Fig 1) revealed no change in the prolonged P-R interval and left anterior fascicul ar block, but new developments of complete right bundle-branch block and pathologic Q waves in leads VI to V4 diagnostic of acute anteroseptal myocardial infarction were noted . The ECG taken earl y on Nov 16 showed no change; however, the ECG taken later on Nov 16 revealed remarkable changes in that R waves reappeared in leads V2 to V4 and the right bundlebranch block disappeared. The ECGs taken on Nov 17 and 18 showed no change. Serum levels of cardiac enzymes on Nov 17, 18, and 19 were abnormally high (Fig 1) . The patient developed left ventricular failure , and on Nov 19 the patient had ventricular fibrillation from which he could not be resuscitated. At necropsy , the heart weighed 630 gm. Extensive atherosclerosis involved all three major coronary arteries. A thrombus completely obliterated the lumen of the left anter ior descending coronary artery beginning 1.0 em from its origin. A recent myocardial infarct involving the ventricular septum and the contiguous anterior wall of the left ventricle was noted on gross examination (Fig 2). Histologic examina-

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FIGURE 4. High posterior left ventricular wall. Note normal myofibers at upper left, and loss of cross-striations, sarcoplasmic clumping, and eosinophilic change in myofibers at lower right (hematoxylin-eosin, original magnification X 550).

FIGURE 2. Anteroseptal infarction. Note thrombosis in left anterior descending coronary artery (arrow) . tion of the sections from this area revealed acute myocardial necrosis with heavy leukocytic infiltration and nuclear fragmentation consistent with an infarction three to five days old ( Fig 3). The posterior wall of the left ventricle was normal on gross examination, but histologic sections revealed early myocardial necrosis without leukocytic infiltration, consistent with an infarction less than three days old'' (Fig 4) . The lungs were markedly congested. DISCUSSION

Pathologic Q waves in the ECG resulting from myocardial infarction may regress or disappear at a later date. The incidence of this phenomenon varies between 1.9 and 16 percent in the reported series,':" depending

FIGURE 3. Anteroseptal infarction. Note myocardial necrosis, polymorphonuclear-cell infiltration, and fragmentation (hernatoxylin-eosin, original magnification X 550) .

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upon the methods and criteria used. In one series of 52 patients, I the mode of disappearance of these Q waves were as follows : "normal evolution" in 69 percent (36); new development of a conduction defect in 24 percent (12); and superimposed myocardial infarction in 8 percent (4). In our case the necropsy findings revealed that the abnormal Q waves in the right precordial leads resulted from a massive anteroseptal infarction. When posterior infarction supervened, these Q waves suddenly disappeared. The resultant electrocardiographic pattern was the summation of two infarctions located in the opposite wall of the left ventricle and was no longer diagnostic of an antcroscptal infarction alone or an isolated posterior infarction. This concept of one infarction erasing the electrocardiographic pattern of a preexisting infarction has been described in the literature;1.6,1.9.10 but, to our knowledge. pathologic correlation of this phenomenon has not been reported previously. Appearance and disappearance of the right bundlebranch block concomitant with the Q waves in this case is distracting. One possibility is that development of an equal amount of delay in conduction in the left bundle as in the right bundle allowed the impulse to propagate in normal fashion, resulting in a disappearance of the right bundle-branch block. Further prolongation of the PR interval on Nov 18 (Fig I) supports this hypothesis. If this was the case, the His-bundle electrogram could have revealed a longer His-ventricle interval with a narrower QRS complex than with right bundle-branch block. Transient abnormal Q waves have been noted in a variety of conditions in the absence of myocardial infarction .1, l l Abnormal Q waves in the right precordial leads have occurred transiently concomitant with right bundlebranch block . and it has been postulated that intermittent septal focal block concomitant with right bundlebranch block is responsible for this ; It however, the necropsy findings in our case unequivocally documented two temporally and spatially separate infarcts, the gross-

SUDDEN DISAPPEARANCE OF ECG PATTERN 403

ly visible anteroseptal infarct and the grossly nonvisible, though microscopically evident, posterior infarct. Sudden normalization of the ECG from a pattern of anteroseptal infarction should alert us to the possibility of superimposed posterior infarction. REFERENCES

1 Kalbfleisch JM, Shadaksharappa KS, Conrad LL, et al: Disappearance of the Q-deflection following myocardial infarction. Am Heart J 76: 193-198, 1968 2 COX CJB: Return to normal of the electrocardiogram after myocardial infarction. Lancet 1: 1194-1197, 1967 3 Kaplan BM, Berkson DM: Serial electrocardiograms after myocardial infarction. Ann Intern Med 60:430-435, 1964 4 Anderssen N, Skjaeggestad 0: The electrocardiogram in patients with previous myocardial infarction. Acta Med Scand 176: 123-126, 1964 5 Pappas MP: Disappearance of pathological Q waves after

cardiac infarction. Br Heart J 20: 123-128, 1958 6 Shadaksharappa KS, Krishnamurthy M: Disappearance of Q wave. J Indian Med Assoc 53:28-29, 1969 7 Gross H, Rubin IL, Arbeit SR: Transitory abnormal Q waves in patients with and without myocardial infarction. Isr J Med Sci 5:701-709, 1969 8 Gould SE: Microscopic changes in myocardial infarcts. In Pathology of the Heart and Blood Vessels (3rd ed). Springfield, 11, Charles C Thomas, 1968, p 616 9 Lipman BS, Massie E, Kleiger RE: Acute infarct superimposed on old infarct. In Clinical Scalar Electrocardiography (6th ed ). Chicago, Year Book Medical Publishers Inc, 1972, p 229 10 Levine HD, Young E, Williams RA: Electrocardiogram and vectorcardiogram in myocardial infarction. Circulation 45:457-470, 1972 11 Gambetta M, Childers RvV: Rate-dependent right precordial Q waves: "Septal focal block." Am J Cardiol 32: 196-201, 1973

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