J. ELECTROCARDIOLOGY 12 (2), 1979, 157-161

Premature Ventricular Contractions in Acute Myocardial Infarction. Correlation Between Their Origin and the Location of Infarction BY SAMUEL SCLAROVSKY, M.D., BORIS STRASBERG, M.D., MEIR LAHAV, M.D., RUBEN F. LEWIN, M.D. AND JACOB AGMON, M.D., F.A.C.C.

SUMMARY The purpose o f this study was to investigate the correl at i on between the origin o f p r e m a t u r e v e n t r i c u l a r c o n t r a c t i o n s (PVC's) appearing during acute myocardial in f ar c t i on (AMI) and the location o f the i n f a r c t i o n as d e t e r m i n e d by the e l e c t r o c a r d i o g r a m (ECG). The PVCs were t erm ed acute or chronic according to the time o f t h e i r appearance. The origin of the PVCs, located at the left ventricle ( a n t e r i o r or p o s t e r i o r wall) or t h e r i g h t v e n t r i c l e , was d e t e r m i n e d by E C G criteria. In 82 out of 91 cases of acute PVCs (90.2%), the PVCs presented an origin similar to the AMI location (p ~< .001). In 23 cases with chronic PVCs, this c o r r e l a t i o n was not observed. In all 13 cases of p r i m a r y v e n t r i e u l a r fibrillation in which the PVCs origin was d e t e r m i n e d prior to the event, the PVCs were acute coming f r om the same location as the AMI. The effectiveness o f lidocaine t r e a t m e n t on PVCs was also determined. Out of 44 cases with acute PVCs, 38 responded to lidocaine, with 37 of t h e m showing an origin similar to the AMI location (p ~< .001); 5 non-responders showed an origin different f r o m the AMI location. No response was observed in 20 out of 23 cases with chroni c PVCs. These results show a good c o r r e l a t i o n between the origin o f the acute PVCs and the location o f the AMI. It is concluded t h a t the d e t e r m i n a t i o n o f the origin o f PVCs appearing during AMI provides f u r t h e r clinical i n f o r m a t i o n as to the location o f AMI, its prognosis in r e l a t i o n to serious a r r h y t h m i a s and the resistance o f c e r t a i n PVCs to lidocaine t r e a t m e n t .

cance since t hey m ay lead to dangerous arr h y t h m i a s like v e n t r i c u l a r fibrillation. 2 PVCs also o c c u r i n c h r o n i c m y o c a r d i a l i s c h e m i c states, such as old myocardial infarction. Wellens et al suggested t h a t the mechanism of ventricular a r r h y t h m i a s in AMI is due to an automatic mechanism, while those occurring in old myocardial infarction are most probably originated from a r e e n t r y circuit. 3 PVCs m ay also be found in pat i ent s without demonstrable h e a r t disease. 4-8 Using ECG criteria, it is possible to determ i n e t h e s i t e of o r i g i n o f P V C s 2 -11 P V C s originating in the left ventricle show a ri ght bundle b r a n c h block (RBBB) p a t t e r n and those originating in the ri ght ventricle, a left b u n d l e b r a n c h block (LBBB) p a t t e r n . Since

PVCs are a common finding in the setting of AMI, 1'2 and t h e i r relation to experimental acute electrophysiological and metabolic c h a n g e s o c c u r r i n g in t h e i s c h e m i c m y o c a r dium have been demonstrated. 2 The presence of PVCs in AMI is of major clinical signifiFrom the Israel and Ione Massada Center for Heart Diseases, Intensive Coronary Care Unit and Institute for Cardiac Rehabilitation, Beilinson Medical Center, Petah-Tikva, Israel. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. w solely to indicate this fact. Reprint requests to: J. Agmon, M.D., Director, Massada Center for Heart Diseases, Beilinson Medical Center, Petah-Tikva, Israel. 157

158

SCLAROVSKY

ET AL

TABLE 1. Correlation Between the Origin of Acute Premature Ventricular Contractions (PVCs) and the Location of the Acute Myocardial Infarction (AMI)

A.

Anterior Wall AMI without old MI n=

B.

Postero-lnferior Wall AMI

Anterior Wall AMI with old PIW-MI n= 12

D.

n

%

LV - AW LV - PIW

31

88.6

4

11.4

p ~< .001

LV - PIW LV - AW RV

24 2 1

89.2 7.2 3.6

p ~< .001

LV - AW

35

without old MI n = 27

C.

Origin of PV Cs

Postero-lnferior Wall AMI with old AW-MI n= 17

11

91.7

LV- PIW

1

8.3

p ~< .001

LV - PIW

16 1

94.2 5.8

p ~< .001

RV

Abbreviations: n =

number of patients; AMI = acute myocardial infarction; LV = ventricle; AW = anterior wall; PIW = postero-inferiar wall.

t h e p u b l i c a t i o n of R o s e n b a u m , 11 c o r r o b o r a t e d e x p e r i m e n t a l l y b y M a u t n e r a n d co-workers, 12 it is n o w also possible to d e t e r m i n e by E C G criteria (axis deviation) the site or origin of the left v e n t r i c l e P V C s f r o m t h e a n t e r i o r or posterior wall. The p u r p o s e of our s t u d y w a s to i n v e s t i g a t e t h e r e l a t i o n s h i p b e t w e e n the E C G location of the A M I a n d t h e origin of the P V C s a n d to s t u d y t h e i r p r o g n o s i s in r e l a t i o n to s e r i o u s arrhythmias and response to lidocaine treatment.

MATERIALS AND METHODS From 1500 patients hospitalized in our Coronary Care Unit with a proved AMI, only 114 patients in whom the diagnosis of the origin of PVCs was obtained were included in this study. To find a closer relationship between AMI and PVCs, patients receiving digitalis, fl-blockers, a n t i - a r r h y t h m i c drugs, diuretics and those with electrolyte disturbances were excluded from this study. The location of the AMI was labelled as follows: a) anterior wall, including anteroseptal and or anterolateral wall; and b) postero-inferior wall. PVCs were defined as QRS complexes of bizarre configuration that were 0.12 sec. or more in duration, were not preceded by a P wave, and were with a shorter coupling to the prior R-R interval. ~4 The ECG criteria used to determine the origin of PVCs using 12 lead ECG were: a) Lead Vz was used to determine the ventricle of origin: RBBB pattern indicated a left ventricular origin, while an LBBB pattern indicated a right ventricular origin2 -~ The rest of the precordial leads (V2 to V6) were used

left ventricle; RV = right

to determine whether the PVCs originated in the apex (negative QRS deflections (QS) from V2 to V6) or in the base (positive QRS deflection (R) from V2 to V6). b) Leads II, III and AVF (axis deviation) determined the anterior or posterior left ventricle wall origin, u-12 PVCs showing left axis deviation with an electrical axis above - 3 0 ~ indicated a postero-inferior wall origin, while PVCs with right axis deviation and an electrical axis beyond + 100 ~ indicated an anterior wall origin. Patients with multifocal PVCs were excluded from the study so that a closer relationship between localization of PVCs and the site of AMI could be obtained. PVCs were divided into the following groups: 1) left ventricle anterior wall, characterized by a RBBB pattern in lead V1 and right axis deviation; 2) left ventricle posterior wall characterized by a RBBB pattern in lead V1 and left axis deviation; 3) right ventricle characterized by a LBBB pattern in lead Vz; and 4) miscellaneous, including PVCs from the apex or base as well as PVCs with normal electrical axis ( - 3 0 ~ to +90~ The PVCs were further divided into two groups according to their time of appearance: acute PVCs, appearing only during the first 48 hours of acute phase of MI; and chronic PVCs, recorded in an ECG prior to the AMI or observed after the first 48 hours of acute phase of MI. 3 Patients without a previous history of ischemic heart disease were considered not to have PVCs prior to the hospitalization, unless PVCs were recorded in previous routine ECG. In patients with old myocardial infarction, discharge ECG or follow-up strips were used as evidence for the presence of chronic PVCs. Patients with acute PVCs were divided into two subgroups: 1) AMI with no history of ECG signs of an old myocardial infarction; and 2) AMI with a history and ECG signs of old myocardial infarction. J. ELECTROCARDIOLOGY, VOL. 12, NO. 2, 1979

P R E M A T U R E V E N T R I C U L A R C O N T R A C T I O N S IN AMI

159

TABLE 2. Comparison of the Origin of Acute and Chronic Premature ventricular contractions (PVCs) and the Location of Acute Myocardial Infarction (AMI) Acute PV Cs

Same Location

Different Location T~_+Y

Chronic PV Cs

n

%

82

90.2

7

30.4

9

9.8

16

69.6

23

p > .05

91

n

p ~< .001

%

Abbreviations - - see Table 1.

Lidocaine in bolus was administered only to the patients who fulfilled Lown's criteria. 15 Lidocaine effectiveness in abolishing the PVCs was compared in all groups. As soon as PVCs origin was determined, lidocaine was administered in IV bolus of 1 mg/kg body weight and thereafter infused continuously at a rate of 2-4 mg/min. A positive response was considered to occur when complete abolishment of the PVCs was observed during the first half hour after the administration of the bolus. 15 Results were analysed for significance by the Chi-Squared Test and the Fischer exact test. TM

RESULTS One hundred and fourteen patients fulfilled all our criteria for the determination of PVCs origin and differentiation between acute and chronic. Ninety-one patients were considered to have acute PVCs while 23 had chronic PVCs. The degree of correlation between the origin of PVCs and the location of the AMI is presented in Table 1 (A-D). A. Origin of acute PVCs in patients with anterior wall AMI without old myocardial infarction. This group consisted of 35 patients. In 31 (88.6%) the PVCs originated in the left ventricle anterior wall (Fig, 1A) while in 4 (11.4%) the o r i g i n was t h e left v e n t r i c l e postero-inferior wall (p ~< .001). B. Origin of acute PVCs in patients with postero-inferior AMI without old myocardial infarction. This group consisted of 27 patients. In 24 (89.2%) the PVCs origin was in the left ventricle postero-inferior wall (Fig. 1B). In the remaining three cases, two (7.2%) showed PVCs originating in the left ventricle anterior wall, while in the last case the origin was the right ventricle (p