British Heart Journal, 1976, 38, 457-464.
Association of ventricular extrasystoles and ventricular tachycardia with idioventricular rhythm S. Talbot and M. Greaves From Sheffield Royal Infirmary, Sheffield
Patients with acute myocardial infarction were monitored for ventricular arrhythmias in the first 48 hours. Idioventricular rhythm (rate less than 100/minute) occurred in 35 out of 224 patients (15.6%) during thefirstday and in 13out of 192 patientsnotreceiving treatment on the second day (6.8%). This arrhythmia was frequently preceded by late ventricular extrasystoles, which often showed variation of their coupling intervals to the preceding QRS. Double ventricular extrasystoles separated by 2600 ms were also precursors of idioventricular rhythm. Idiovetitricular rhythm at times could be described as an escape rhythm, but on other occasions it was undoubtedly an accelerated rhythm. Spontaneous changes in the idioventricular cycle length were frequent on single one-minute electrocardiographic recordings. The rate of the dominant rhythm in patients with episodes of idioventricular rhythm was significantly slower than the heart rate of patients without .his arrhythmia. Idioventricular rhythm was tore frequent in patients with inferior infarction. Idioventricular rhythm sometimes preceded ventricular tachycardia but there was only a significant association between ventricular tachycardia and idioventricular rhythms with rates of over 75/minute. Irregular idioventrcular rhythmfrequently accelerated to ventricular tachycardia. It is suggested that the term benign idioventricular rhythm be reservedfor those rhythms below 75/minute, and that the term rapid idioventricular rhythm should be usedfor rhythms between 75 and 120/minute. The rate of idioventricular rhythm is related to the probability of development of life-threatening ventricular arrhythmias during the first 48 hours after myocardial infarction. Idioventricular rhythm and ventricular tachycardia are not clearly separated in many early analyses of the arrhythmias occurring after acute myocardial
100 to 120 beats a minute (Rothfield et al., 1968; Norris et al., 1970; De Soyza et al., 1974a). In this study the importance of these 'slow' ventricular rhythms after acute myocardial infarction and their relations with ventricular tachycardia and measures of ventricular extrasystolic activity have been examined.
infarction (Julian, Valentine, and Miller, 1964; Fluck et al., 1967; Lawrie et al., 1968). However, subsequently it has been found that slow ventricular rhythms are more benign than faster rhythms (Rothfield et al., 1968; Norris, Mercer, and Yeates, 1970). Many idioventricular rhythms are critically Patients and methods dependent on the underlying heart rate, appearing when this slows and disappearing when the sinus Between January 1974 and November 1974 269 patients rhythm accelerates. The terms 'slow' and 'benign' with acute myocardial infarction were admitted to the idioventricular rhythm have become popular. coronary care unit of the Sheffield Royal Infirmary: Though the extremes of rate of idioventricular 31 patients died in cardiogenic shock during the first rhythm and ventricular tachycardia do justify such 48 hours after myocardial infarction, and 5 patients were of complete 6 hours becausewho pacedblock. withinThese easy tonly to prderats provide a definition it is notthat a dthese distinction, not easy were on andofa admission further 9 patients theftion heart hion,ai Of of these arrhythmias that not only separates their antiarrhythmic therapy on admission were excluded electrocardiographic features but also their clinical from the study. The remning 224 patients formed the significance. Therefore, the dividing line between subject of this study. The patients were monitored continuously by the these arrhythmias has been variously drawn at nursing staff for at least 48 hours and electrocardioReceived 13 October 1975.
458 Talbot and Greaves graphic recordings were taken of any episodes of idioventricular rhythm or ventricular tachycardia. The nursing staff recorded the number of ventricular extrasystoles at hourly intervals. If at these times the number of ventricular extrasystoles was >5/minute a oneminute electrocardiographic recording was taken and this was repeated at 6-hourly intervals for 48 hours. Similar observations were made at other times if ventricular extrasystoles appeared or increased in number. A clinical assessment of each patient was made on admission and at least daily thereafter throughout the patient's stay in hospital. Daily 12-lead electrocardiograms and at least one chest radiograph were performed in the first 48 hours. Antiarrhythmic therapy was not used routinely but was given for ventricular tachycardia or after an episode of ventricular fibrillation. An episode of ventricular tachycardia was diagnosed when there were three or more ventricular extrasystoles in a row separated from each other on average by 600 ms and ventricular bigeminy lasting for at least a minute were recorded separately. - The diagnosis of myocardial infarction was made electrocardiographically and confirmed by serum enzyme tests (Blackburn et al., 1960; Goldberg and Winfield, 1972). The location of infarction was described as anterior, inferior, septal, or lateral or any combination of these (Talbot et al., 1973). The time of onset of infarction was determined from the clinical history and emination in conjunction with the results of three serum enzyme tests on consecutive days. If these were conflicting a further history was taken to elucidate if and when one or more infarctions had occurred.
Results On the first day after infarction 35 out of 224 patients had one or more episodes of idioventricular rhythm. Thirty-two patients received treatment for ventricular tachycardia or ventricular fibrillation and,
therefore, on the second day only 192 patients could be studied further. Nine of these patients had one or more episodes of idioventricular rhythm
in the second 24 hours after infarction. In all, 44 ents had idi rhythm. Seventeen of paties also had ventricular tachycardia. these patients alsoventricular In 12 patients idioventricular rhythm clearly preceded ventricular tachycardia, whereas in 5 patients idioventricular rhythm was interspersed with episodes of ventricular tachycardia and the initial arrhythmia could not be determined. Forty-two patients developed ventricular tachycardia during the 48-hour period. There was a significant association between idioventricular rh ythm and subsequent episodes of ventricular tachycardia (X2 17e1, Pi
Association of ventricular extrasystoles and ventricular tachycardia with idioventricular rhythm S. Talbot and M. Greaves From Sheffield Royal Infirmary, Sheffield
Patients with acute myocardial infarction were monitored for ventricular arrhythmias in the first 48 hours. Idioventricular rhythm (rate less than 100/minute) occurred in 35 out of 224 patients (15.6%) during thefirstday and in 13out of 192 patientsnotreceiving treatment on the second day (6.8%). This arrhythmia was frequently preceded by late ventricular extrasystoles, which often showed variation of their coupling intervals to the preceding QRS. Double ventricular extrasystoles separated by 2600 ms were also precursors of idioventricular rhythm. Idiovetitricular rhythm at times could be described as an escape rhythm, but on other occasions it was undoubtedly an accelerated rhythm. Spontaneous changes in the idioventricular cycle length were frequent on single one-minute electrocardiographic recordings. The rate of the dominant rhythm in patients with episodes of idioventricular rhythm was significantly slower than the heart rate of patients without .his arrhythmia. Idioventricular rhythm was tore frequent in patients with inferior infarction. Idioventricular rhythm sometimes preceded ventricular tachycardia but there was only a significant association between ventricular tachycardia and idioventricular rhythms with rates of over 75/minute. Irregular idioventrcular rhythmfrequently accelerated to ventricular tachycardia. It is suggested that the term benign idioventricular rhythm be reservedfor those rhythms below 75/minute, and that the term rapid idioventricular rhythm should be usedfor rhythms between 75 and 120/minute. The rate of idioventricular rhythm is related to the probability of development of life-threatening ventricular arrhythmias during the first 48 hours after myocardial infarction. Idioventricular rhythm and ventricular tachycardia are not clearly separated in many early analyses of the arrhythmias occurring after acute myocardial
100 to 120 beats a minute (Rothfield et al., 1968; Norris et al., 1970; De Soyza et al., 1974a). In this study the importance of these 'slow' ventricular rhythms after acute myocardial infarction and their relations with ventricular tachycardia and measures of ventricular extrasystolic activity have been examined.
infarction (Julian, Valentine, and Miller, 1964; Fluck et al., 1967; Lawrie et al., 1968). However, subsequently it has been found that slow ventricular rhythms are more benign than faster rhythms (Rothfield et al., 1968; Norris, Mercer, and Yeates, 1970). Many idioventricular rhythms are critically Patients and methods dependent on the underlying heart rate, appearing when this slows and disappearing when the sinus Between January 1974 and November 1974 269 patients rhythm accelerates. The terms 'slow' and 'benign' with acute myocardial infarction were admitted to the idioventricular rhythm have become popular. coronary care unit of the Sheffield Royal Infirmary: Though the extremes of rate of idioventricular 31 patients died in cardiogenic shock during the first rhythm and ventricular tachycardia do justify such 48 hours after myocardial infarction, and 5 patients were of complete 6 hours becausewho pacedblock. withinThese easy tonly to prderats provide a definition it is notthat a dthese distinction, not easy were on andofa admission further 9 patients theftion heart hion,ai Of of these arrhythmias that not only separates their antiarrhythmic therapy on admission were excluded electrocardiographic features but also their clinical from the study. The remning 224 patients formed the significance. Therefore, the dividing line between subject of this study. The patients were monitored continuously by the these arrhythmias has been variously drawn at nursing staff for at least 48 hours and electrocardioReceived 13 October 1975.
458 Talbot and Greaves graphic recordings were taken of any episodes of idioventricular rhythm or ventricular tachycardia. The nursing staff recorded the number of ventricular extrasystoles at hourly intervals. If at these times the number of ventricular extrasystoles was >5/minute a oneminute electrocardiographic recording was taken and this was repeated at 6-hourly intervals for 48 hours. Similar observations were made at other times if ventricular extrasystoles appeared or increased in number. A clinical assessment of each patient was made on admission and at least daily thereafter throughout the patient's stay in hospital. Daily 12-lead electrocardiograms and at least one chest radiograph were performed in the first 48 hours. Antiarrhythmic therapy was not used routinely but was given for ventricular tachycardia or after an episode of ventricular fibrillation. An episode of ventricular tachycardia was diagnosed when there were three or more ventricular extrasystoles in a row separated from each other on average by 600 ms and ventricular bigeminy lasting for at least a minute were recorded separately. - The diagnosis of myocardial infarction was made electrocardiographically and confirmed by serum enzyme tests (Blackburn et al., 1960; Goldberg and Winfield, 1972). The location of infarction was described as anterior, inferior, septal, or lateral or any combination of these (Talbot et al., 1973). The time of onset of infarction was determined from the clinical history and emination in conjunction with the results of three serum enzyme tests on consecutive days. If these were conflicting a further history was taken to elucidate if and when one or more infarctions had occurred.
Results On the first day after infarction 35 out of 224 patients had one or more episodes of idioventricular rhythm. Thirty-two patients received treatment for ventricular tachycardia or ventricular fibrillation and,
therefore, on the second day only 192 patients could be studied further. Nine of these patients had one or more episodes of idioventricular rhythm
in the second 24 hours after infarction. In all, 44 ents had idi rhythm. Seventeen of paties also had ventricular tachycardia. these patients alsoventricular In 12 patients idioventricular rhythm clearly preceded ventricular tachycardia, whereas in 5 patients idioventricular rhythm was interspersed with episodes of ventricular tachycardia and the initial arrhythmia could not be determined. Forty-two patients developed ventricular tachycardia during the 48-hour period. There was a significant association between idioventricular rh ythm and subsequent episodes of ventricular tachycardia (X2 17e1, Pi
