Prognostic Profile of Fascicular Blocks in. Murlidhar S. RAO, M.D., F.I.C.A.* and Jayant ANTANI, M.D., F.A.C.C., F.C.C.P., F.I.C.A.

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1 Prognostic Profile of Fascicular Blocks in Myocardial Infarction Murlidhar S. RAO, M.D., F.I.C.A.* and Jayant ANTANI, M.D., F.A.C.C., F.C.C.P., F.I.C.A.** SUMMARY An analysis of 69 cases of bifascicular and trifascicular types of intraventricular conduction disturbances in myocardial infarction is presented. Complications, causes of death and the follow-up of unpaced cases for a year have been recorded. Pump failure and severe degrees of blocks with consequent ventricular asystole are the important causes of death. Recurrent pump failure with occasional fatal outcome is more common in cases with RBBB and LAH than in other types of blocks. Additional Indexing Words: Arrhythmia Hemi-block Intraventricular conduction disturbances CUTE myocardial infarction is associated with a variety of arrhythmias. Heart blocks at the A-V junctional or intraventricular level form a very significant group of conduction disturbances. While the A-V node is more susceptible to acute lesions and the blocks therein are usually transient and rarely become "chronic",1) the intraventricular blocks due to lesions of bundle of His and its ramifications, are more "stable" and usually "chronic". Since the work of Rosenbaum et al,2) the concept of intraventricular heart-blocks has crystallised into monofascicular (involvement of main bundle), bifascicular (involvement of any 2 divisions of the main bundle branch), and trifascicular (involvement of right bundle and the 2 divisions of left bundle). As many as 12 possible varieties of intraventricular bifascicular blocks and 8 possible varieties of trifascicular blocks, have been postulated by Rosenbaum et al.3) It is now well known that the occurrence of such intraventricular conduction disturbances in myocardial infarction have prognostic significance From the Department of Medicine (Cardiology), M.R. Medical College, Gulbarga , India. * Consultant Physician, Associate Professor of Medicine ** Consultant Cardiologist, Professor of Medicine Part of this work was presented at the 30th Annual Conference of Association of Physicians of India held in January 1975, at Bangalore. Address for reprint request: Jayant Antani, M.D., Mill Road, Gulbarga , India. Received for publication November 16,

2 Vol.18 No.3 PROGNOSIS OF FASCICULAR BLOCKS 407 and greatly increase the probability of severe complete heart block.4),5) Our earlier observation regarding the prognosis of right bundle branch block (RBBB) with left anterior hemi-block (LAH) in myocardial infarctions6) has been extended to other types of bifascicular and trifascicular blocks. We report in the present work, prognosis of various types of bifascicular and trifascicular blocks in myocardial infarction, their complications with special emphasis on pump failure and the survival of such cases during a period of observation of over 1 year, in personal cardiac practice and in medical unit of Govt. General Hospital, Gulbarga. MATERIALS AND METHODS A total of 69 cases of bifascicular and trifascicular blocks in acute myocardical infarction were seen and followed by us between 1966 and The diagnosis of complete left and right bundle-branch block was based on criteria proposed by the New York Heart Association (1964).7) Blocks of the anterior and posterior fascicles of left bundle-branch and the trifascicular blocks were diagnosed according to criteria proposed by Rosenbaum2) (Figs. 1-7). There were 12 females and 57 males (1:4.8). Average age was 58.5 years, the oldest being 95 years and youngest 38 years. All the cases were seen in acute phase except those who died in first few hours before medical care was available. The electrocardiograms were recorded frequently for first 72 hours, later every alternate day for ten days and Fig.1. RBBB with LAH in extensive infarction in a 42-year-old man who died 21/2 years after the initial attack as a result of intractable congestive heart failure.

3 408 RAO AND ANTANI Jap. Heart J. May, 1977 Fig.2. RBBB with LAH in acute anterior myocardial infarction in a 58-year-old man who suffered from recurrent episodes of pump failure till he succumbed to the final one after 5 months of initial attack. Fig.3. RBBB with LPH in acute extensive anterior infarction in a 48-year-old man who is still living. QRS axis initially was +104 but changed slowly in subsequent ECGs in 6 months to +130.

4 Vol.18 PROGNOSIS OF FASCICULAR BLOCKS 409 No.3 Fig.4. LBBB with prolonged P-R interval with occasional RBBB pattern in V1 suggestive of bi-or even trifascicular block in a 60-year-old diabetic lady. later every week till sixth week. In case of any change in the cardiac rhythm or other complications, EKGs were taken more frequently. Regular follow-up with EKGs, at least once in 2 weeks for another 3 months, was maintained and later on monthly follow-up for the rest of the year. In the event of death, the cause of death as far as possible was analysed. The total duration of survival of each patient was recorded. The patients were radiographed for the pulmonary complications during the follow-up. The patients with complete heart block were closely studied without artificial pacing. RESULTS The various types of bifascicular and trifascicular blocks observed, have been analysed in relation to the site of infarction and the mortality in the course of 1 year of observation. It is obvious (Table I) that the anterior wall is the most likely site of infarction in cases with fascicular blocks (82.6%). In fact, trifasicular blocks occurred only in cases with anterior wall infarctions. The nature of complications observed in some of these cases has been

5 410 RAO AND ANTANI Jap. Heart J. May, 1977 Fig.5. LAH with prolonged P-R interval in a 64-year-old diabetic man with recent MI, who died of pump failure. analysed (Tables II, III). The progressive atrioventricular block, leading to complete heart block with Stokes-Adams' attacks occasionally accompanied by ventricular asystole, occurred in 18 cases, all of which died in a year's follow-up. They occurred in the first 72 hours of the observation in the 6 cases who ultimately died. Another 6 cases developed this complication in the course of a month and died. The remaining had complete heart block after a month and died during the year. In the majority of the cases, I or II degree A-V block was the only inital complication which later on progressed to complete heart block. It was difficult to know the exact time of the occurrence of each block, during the year-long follow-up. Pump failure occurred in as many as 26 cases (37.7%). It was a dominant feature in 14 patients who died within 1 year follow-up. In a number of deaths due to complete heart block, pump failure was also a feature but was presumed to be the secondary complication. Quite a few cases of pump failure were complicated by intractable congestive cardiac failure. Sudden syncopal attacks with critical fall of blood pressure without change in EKG pattern, indicating recurrent episodes of unexplained pump failure occurred in 5 cases and of these, it proved fatal in 3. In 4 of the 14 fatal cases, the

6 Vol.18 No.3 PROGNOSIS OF FASCICULAR BLOCKS 411 Fig.6. RBBB with LPH who soon went into complete heart block and later died of ventricular asystole. Fig.7. RBBB with LAH and I degree A-V block, an instance of trifascicular block in a 72-year-old man who suffered from frequent Stokes- Adams' attacks.

7 412 RAO AND ANTANI Jap. Heart J. May, 1977 Table I. Blocks in Relation to Site of Infarction The other types of bi-and trifascicular blocks not observed in this series, are not mentioned. RBBB: Right bundle-branch block, LAH: Left anterior hemi-block, LBBB: Left bundlebranch block, A-V block: Atrio-ventricular block, LPH: Left posterior hemi-block, ANT Anterior, INF: Inferior, MULT: Multiple. Table II. Complications VPCs: Ventricular premature contractions, PAT: Paroxysmal atrial tachycardia, VT: Ventricular tachycardia. Table III. Complications in Fatal Cases During 1 Year * Additional 5 patients died of this, after 1 year. õ Another patient died, after 1 year. LAH: Left anterior hemi-block, LPH: Left posterior hemi-block, A-V block: Atrio-ventricular block, INTR CHF: Intractable congestive heart failure.

8 Vol.18 No.3 PROGNOSIS OF FASCICULAR BLOCKS 413 Table IV. Survival Rate in 1 Year Follow-up RBBB: Right bundle-branch block, LAH: Left anterior hemi-block, LPH: Left posterior hemi-block, A-V block: Atrio-ventricular block. chest X-ray showed moderate pulmonary congestion and in one of them there was an area of small infarct. Our observations showed that although the pump failure occurred in majority of these cases in the first 4 weeks of the follow-up, it recurred in an unexplained and dramatic way, till it ended fatally in 14 patients during the year. In 2 of the 19 cases complicated by congestive heart failure, it was the principal cause of death during the follow-up. Table IV shows the duration of survival of the patients who had complications during the follow-up. Thirty-four out of 69 cases (49.17%) died within 1 year. Only 12 of them died within the first month of the treatment. Of the 35 survivors, who lived for more than a year, 6 died later. Electrocardiographic pattern of these blocks, seen at the onset, either remained stable throughout, or changed to complete or high grade blocks in the followup, but never disappeared in our series. DISCUSSION Many authors have reported that bifascicular and trifascicular blocks occurring in acute myocardial infarction indicate a higher mortality than uncomplicated myocardial infarction.6),8)-10) The incidence of intraventricular conduction disturbances in acute myocardial infarction in one well documented series of 325 consecutive cases admitted to a coronary care unit was 25% among which half had bi- or trifascicular blocks.10) The mortality in the patients with more than one intraventricular conduction defect was 47%, whereas it was only 11% in those without any intraventricular conduction disturbance. It is also now

9 414 RAO AND ANTANI J ap. Heart J. May, 1977 widely accepted that these intraventricular conduction disturbances are the forerunner of complete heart block with Stokes-Adams' attacks and pump failure which may prove to be the fatal complications. Although pacing has been used routinely in these cases at some centres, the benefit of such routine pacemaker therapy for patients with heart block complicating myocardial infarction has not been established, as there does not appear to be a direct relationship between pacemaker insertion and mortality.11) The mortality figures in the series using routine pacemaker and those not using, do not differ significantly.12),13) The present work has given us an opportunity to study the mortality and the long survial of unpaced patients. The present observations, though over a limited period, have revealed that the RBBB with LAH is the most common type of bifascicular block in myocardial infarction. This increased susceptibility of the right bundle and the anterior fascicle of left bundle to conduction disturbances has been explained on the basis of anatomical peculiarities.14),15) Among the 10 cases of RBBB with LAH, who died during the first 4 weeks of observation, 4 died within 72 hours of onset of myocardial infarction. Eleven cases who survived first month, died within a year. Progression to complete heart block with cardiac asystole (in 10 cases) and the pump failure (in 10 cases) were the major cause. Another case died of intractable congestive heart failure. Five of those cases who lived over 1 year died later in the course of 2 years. RBBB with LPH was the next common intraventricular conduction disturbance in our series. One of the 5 deaths with this complication occurred within 48 hours of onset due to ventricular asystole. The other 4 cases who died within 1 year were complicated by A-V conduction disturbances and congestive cardiac failure. Severe cardiogenic shock probably was a feature in one of those cases. It is premature to conclude anything on this small series, but A-V conduction disturbances are more common in these cases than the pump failure, probably for the reasons of anatomical and circulatory vulnerability of posterior fascicle of left bundle branch.5) Five out of 10 of other varieties of bifascicular blocks died of pump failure complicated by intractable congestive heart failure. Three out of 5 cases of trifascicular block died within 6 months of onset. One of them died suddenly within 12 hours. Ventricular asystole was the cause in all the 3 deaths. Pump failure was not an important feature in these cases although it occurred at the onset in 2 cases which are living. The foregoing analysis of the survival of the cases and the causes of death in those who died, reveals that the 2 important complications: severe degree of complete A-V block with its occasional consequent ventricular asystole and severe pump failure, frequently occur in many of these cases and

10 Vol.18 No.3 PROGNOSIS OF FASCICULAR BLOCKS 415 herald a very bad prognosis. Whilst the cases with RBBB with LAH are likely to have both the above complications, the cases with other types of bifascicular and trifascicular blocks appear to be more prone to severe degrees of A-V block than pump failure. This is an interesting as well as significant observation in view of the selection of the patients for emergent pacing and its usefulness. Severe pump failure which takes away quite a large number of patients with RBBB with LAH will not be protected by pacing and other vigorous therapeutic measures often fail as well. REFERENCES 1. Rosenbaum MB, Elizari MV, Krets A, Tarute, AL: Anatomical basis of A-V conduction disturbances. In: Symposium on Cardiac Arrhythmias, Elsimore, Denmark, 147, Rosenbaum MB, Elizari MV: Los Hemibloques, Quoted by 1, ed Paidos, Buenos Aires, Rosenbaum MB, Elizari MV, Lazzari JO, Nau GJ, Levi RJ, Halpern MB: Intraventricular trifascicular blocks, review of literature and classification. Am Heart J 78: 450, Kulbertus H, Collignon P: Association of RBBB with left superior or inferior intraventricular block. Its relation to complete heart block. Brit Heart J 31: 435, Rosenbaum MB, Elizari MV, Lazzari JO, Halpern MS, Ryba D: QRS patterns heralding the development of complete heart block with particular emphasis on RBBB with LPH. In: Symposium on Cardiac Arrhythmias, 249, Antani J, Rao MS: Prognosis of RBBB with LAH in myocardial infarction. J Asso Phys India 20: 630, New York Heart Association, Criteria Committee: Diseases of Heart and Blood Vessels. Nomenclature & Criteria for Diagnosis. 6th Ed, Churchill, London, p421, Roos JC, Dumming AJ: RBBB with left axis deviation in acute myocardial infarction. Brit Heart J 32: 847, Datey KK, Nathwani AN: Some observations in the management of 300 cases of acute myocardial infarction in ICCU. J Asso Phys India 18: 481, Rizzon P, Di Biase M: Intraventricular conduction defects in acute myocardial infarction. Brit Heart J 36: 660, Gupta PK, Licksetin E, Chadda KD: Heart block complicating acute inferior wall infarction. Chest 69: 599, Friedberg CK, Cohen H, Donaso E: Advanced heart block as complication. Role of pacemaker. Prog Cardiovasc Dis 10: 466, Rotman M, Wagner GS, Wallace AG: Bradyarrhythmias in acute myocardial infarction. Circulation 45: 703, Schamroth L: Bilateral bundle branch block. In: Disorders of Cardiac Rhythm, Black Well Scientific Publications, Oxford, p182, Rosenbaum MB: Types of RBBB and their clinical significance. J Electrocardiol 1: 221, 1968