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Reevaluation of the Criterion for Interatrial Block
Reevaluation of the Criterion for Interatrial Block Vignendra Ariyarajah, MDa,b,*, Mary E. Frisella, MDc, and David H. Spodick, MDc The importance of the interatrial block has often been overshadowed by the debate on the appropriate cutoff to define its excessively wide P waves. However, by far, most publications have accepted P waves of >110 ms to represent abnormal interatrial conduction on the electrocardiogram. These “guidelines” have been structured on anachronistic electrocardiographic standards mostly determined from references to earlier textbooks and other publications that often did not involve original work. As such, reevaluation of the top normal value for the P-wave duration in adults is probably long overdue. We reevaluated the prevalence of interatrial block in our previously published series of 500 outpatients using existing standards for normal P-wave values and compared these results with the previous known prevalence of interatrial block to generate this present report. In conclusion, the frequency of the mode duration for P waves (120 ms) suggests electrophysiologic reevaluation of the normal range. © 2006 Elsevier Inc. All rights reserved. (Am J Cardiol 2006;98:936 –937) On the electrocardiogram (ECG), time equals the duration of conduction and excessive time or delay equals a block. Thus, such an abnormality between the atria is commonly termed an interatrial conduction delay or interatrial block (IAB) and is depicted on the ECG as wide, often bifid, P waves (94% prevalence, sensitivity 75%, specificity 94% for IAB recognition, positive predictive value 94%, p ⬍0.0001).1,2 Textbooks have frequently cited a P wave of ⬍110 ms on the ECG as the top normal cutoff to represent and distinguish normal from abnormal interatrial conduction.3–5 We have published widely on the near ubiquity of IAB in older hospital populations.6 – 8 For specificity and because 1 mm represents 40 ms on standardized ECGs,9 we have often considered ⱖ120-ms P waves as our diagnostic criterion.6 – 8,10 Through the course of our work, we also noted that 120 ms is by far the most recorded value in several general hospitals7–9 and, quite recently, among outpatients.11 We reevaluated our data using P waves of ⱖ110 ms and ⱖ100 ms for diagnosing IAB in this latter group to better understand the true extent of this veritable pandemic and to establish the backbone for our discussion on the need to reevaluate the normal P-wave cutoff in adults.
sachusetts has been previously described.11 In brief, 12-lead ECGs at rest were recorded using 25 mm/s and 10 mm/mV standardization. The ECGs had been independently evaluated for IAB to the nearest 10 ms using the greatest P-wave duration in every appropriate lead as measured on a blinded, single read with a magnifying graticule by 2 of the investigators (DHS and MEF). At the conclusion of data collection, reconciliation involved 17 patients (3.4% interobserver variability). The onset of the P wave was defined as the junction between the isoelectric TP baseline and the beginning of the P deflection, and the offset was defined as the junction between the end of the P deflection and the PR segment.9 A total of 469 patients remained after excluding those with atrial arrhythmias or technically poor tracings. The P-wave measurements ranged from 40 to 170 ms (mean ⫾ SD 109.2 ⫾ 15.47; Table 1). Although the mode P-wave duration remained at 120 at ms (159 cases), data reevaluation using other “normal” cut-off P-wave values as proposed by textbook standards revealed that using a P wave of ⬍110 ms and of ⬍100 ms to define normal interatrial conduction on the ECG inflated the prevalence of IAB to 53% (247 patients) and 86% (402 patients), respectively.
Methods and Results
Discussion
The design of our recently published series in which we had measured 500 consecutively numbered, otherwise unselected, ECGs of outpatients from the University of Mas-
We had previously reported a 41%8 and 47%7 prevalence of IAB in 2 separate, but comparable, groups of 1,000 hospitalized patients each. We concluded that IAB could be pandemic in the general hospital population compared with other common types of conduction blocks, especially in those aged ⱖ60 years. In a series of community-dwelling men and women ⬎60 years old who were enrolled in the Elder Service Plan, a model of the Program of All-inclusive Care for the Elderly (PACE), we found a similarly high prevalence of 43% for IAB.6 Although the World Health Organization/International Society and Federation of Cardiology Task Force has defined the normal P-wave duration as ⬍110 ms,12 some textbooks have persistently recom-
a
Massachusetts Veterans Epidemiology Research and Information Center, Veterans Affairs Boston Healthcare System; and bDepartment of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts; and cDepartment of Medicine, Division of Cardiovascular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts. Manuscript received February 2, 2006; revised manuscript received April 22, 2006 and accepted April 25, 2006. *Corresponding author: Tel: 617-943-0046; fax: 857-364-4424. E-mail address: [email protected] (V. Ariyarajah). 0002-9149/06/$ – see front matter © 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.amjcard.2006.04.036
www.AJConline.org
Arrhythmias and Conduction Disturbances/Reevaluation of Criterion for Interatrial Block Table 1 P-wave duration measurements among outpatients in sinus rhythm (n ⫽ 469) P-wave Duration (ms) 40 80 90 100 110 120 130 140 150 160 170
No. of Cases (%) 1 (⬍1%) 22 (5%) 44 (9%) 155 (33%) 44 (9%) 159 (34%) 23 (5%) 14 (3%) 2 (⬍1%) 4 (⬍1%) 1 (⬍1%)
mended a ⬍100-ms cutoff for the top normal value. One publication, among the most authoritative, represented a dichotomy of opinions by recommending 100 and 110 ms in the same paragraph.5 If we had used a P wave of 100 ms as the top normal cut-off value in this reevaluation series of outpatients who were presumably younger and could be considered “less sick,” the IAB prevalence, instead of being understandably somewhat lower, would have increased to 86%. Conversely, selecting a value higher than the mode, although reasonable, could perhaps allow for more falsenegative findings (9% prevalence with a 130-ms cut-off value).13 The prevalence of IAB even when a P wave ⱖ120 ms was used in this outpatient cohort remained high (43%, as previously reported)11; hence, the pandemic reference even under the most erudite standards. We have also consistently found that the mode P-wave duration in our investigations was 120 ms, and, for increased specificity, we have certainly used this measurement for the diagnosis of IAB.6 – 8,10,11 Although our purpose has strictly not been to challenge the World Health Organization (or any) guideline, nor to replace a diagnostic criterion, most standardized 12-lead electrocardiographic tracings use 10 ms at 25 mm/s, a recording that equals 1/4 mm. As such, measuring the P-wave durations in 40-ms multiples (1 mm on the ECG), for example, could be more practical when a P wave of ⱖ120 ms (3 mm on the ECG) is used for the diagnosis of IAB at the bedside.9 We, however, acknowledge that even the widest P wave taken from a tracing of a standard bedside ECG sometimes cannot be accurately established by manual estimation, especially when of low or very low voltage. Neither the true onset nor offset of the P wave can perhaps be so determined even under magnification. Moreover, P-wave durations measured in this manner may only rarely precisely correlate with the actual total atrial activation time recorded during electro-
937
physiologic evaluations. However, altering the sweep speed or gain of the ECG in an attempt to achieve optimal results for the diagnosis of IAB could be impractical at the bedside, where the inimitable essence of this inexpensive, quick, and efficient clinical tool is most desired.9 The current recommendations for the top normal interatrial conduction time are, however, based on references to earlier textbooks and other publications that often did not involve original work and, therefore, probably require reevaluation, particularly epidemiologists who could have more realistic normal standards. 1. Bayes de Luna A. Electrocardiographic alterations due to atrial pathology. In: Clinical Electrocardiography: A Textbook. New York: Futura; 1998:169 –171. 2. Ariyarajah V, Apiyasawat S, Puri P, Spodick DH. Specific electrocardiographic markers of P-wave morphology in interatrial block. J Electrocardiol, in press. 3. Waldo AL, Wit AL. Mechanisms of cardiac arrhythmias and conduction disturbances. Part 4. Rhythm and conduction disturbances. In: Fuster V, Alexander RW, O’Rourke RA, eds. Hurst’s The Heart. 10th Edition. New York: McGraw-Hill, 2000:757–796. 4. Slotwiner DJ, Stein KM, Markowitz SM, Mittal SM, Scheiner M, Christini DJ, Lerman BB. Electrophysiology of cardiac arrythmias. Section IV. Disorders of rhythm and conduction. In: Rosendorff C, ed. Essential Cardiology: Principles and Practice. Philadelphia: WB Saunders, 2001:285–308. 5. MacFarlane PW. Atrial enlargement and overload. In: MacFarlane PW, Veitch Lawrie TD, eds. Comprehensive Electrocardiology: Theory and Practice in Health and Disease, 1st ed. Vol 1. Elmsford, NY: Pergamon Press; 1989:662– 664. 6. Ariyarajah V, Puri P, Kranis M, Wilner DA, Spodick DH. Prevalence of interatrial block in the Program of All-inclusive Care for the Elderly (PACE). Am J Ger Cardiol, 2006;15:174 –177. 7. Asad N, Spodick DH. Prevalence of interatrial block in a general hospital population. Am J Cardiol 2003;91:609 – 610. 8. Jairath UC, Spodick DH. Exceptional prevalence of interatrial block in a general hospital population. Clin Cardiol 2001;24:548 –550. 9. Ariyarajah V, Apiyasawat S, Spodick DH. Optimal P-wave duration for bedside diagnosis of interatrial block. Ann Noninvas Electrocardiol, 2006;11:259 –262. 10. Goyal SB, Spodick DH. Electromechanical dysfunction of the left atrium associated with interatrial block. Am Heart J 2001;142:823– 827. 11. Frisella ME, Spodick DH. Confirmation of the prevalence and importance of a 12-lead investigation for diagnosis. Am J Cardiol 2005;96: 696 – 697. 12. Willems JL, Robles de Medina EO, Bernard R, Coumel P, Fisch C, Krikler D, Mazur NA, Meijler FL, Mogensen L, Mort P, et al, for the World Health Organizational/International Society and Federation for Cardiology Task Force Ad Hoc Committee. Criteria for intraventricular conduction disturbances and pre-excitation. J Am Coll Cardiol 1985;5:1261–1275. 13. Ascione R, Caputo M, Calori G, Lloyd CT, Underwood MJ, Angelini GD. Predictors of atrial fibrillation after conventional and beating heart coronary surgery. Circulation 2000;102:1530 –1535.
sachusetts has been previously described.11 In brief, 12-lead ECGs at rest were recorded using 25 mm/s and 10 mm/mV standardization. The ECGs had been independently evaluated for IAB to the nearest 10 ms using the greatest P-wave duration in every appropriate lead as measured on a blinded, single read with a magnifying graticule by 2 of the investigators (DHS and MEF). At the conclusion of data collection, reconciliation involved 17 patients (3.4% interobserver variability). The onset of the P wave was defined as the junction between the isoelectric TP baseline and the beginning of the P deflection, and the offset was defined as the junction between the end of the P deflection and the PR segment.9 A total of 469 patients remained after excluding those with atrial arrhythmias or technically poor tracings. The P-wave measurements ranged from 40 to 170 ms (mean ⫾ SD 109.2 ⫾ 15.47; Table 1). Although the mode P-wave duration remained at 120 at ms (159 cases), data reevaluation using other “normal” cut-off P-wave values as proposed by textbook standards revealed that using a P wave of ⬍110 ms and of ⬍100 ms to define normal interatrial conduction on the ECG inflated the prevalence of IAB to 53% (247 patients) and 86% (402 patients), respectively.
Methods and Results
Discussion
The design of our recently published series in which we had measured 500 consecutively numbered, otherwise unselected, ECGs of outpatients from the University of Mas-
We had previously reported a 41%8 and 47%7 prevalence of IAB in 2 separate, but comparable, groups of 1,000 hospitalized patients each. We concluded that IAB could be pandemic in the general hospital population compared with other common types of conduction blocks, especially in those aged ⱖ60 years. In a series of community-dwelling men and women ⬎60 years old who were enrolled in the Elder Service Plan, a model of the Program of All-inclusive Care for the Elderly (PACE), we found a similarly high prevalence of 43% for IAB.6 Although the World Health Organization/International Society and Federation of Cardiology Task Force has defined the normal P-wave duration as ⬍110 ms,12 some textbooks have persistently recom-
a
Massachusetts Veterans Epidemiology Research and Information Center, Veterans Affairs Boston Healthcare System; and bDepartment of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts; and cDepartment of Medicine, Division of Cardiovascular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts. Manuscript received February 2, 2006; revised manuscript received April 22, 2006 and accepted April 25, 2006. *Corresponding author: Tel: 617-943-0046; fax: 857-364-4424. E-mail address: [email protected] (V. Ariyarajah). 0002-9149/06/$ – see front matter © 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.amjcard.2006.04.036
www.AJConline.org
Arrhythmias and Conduction Disturbances/Reevaluation of Criterion for Interatrial Block Table 1 P-wave duration measurements among outpatients in sinus rhythm (n ⫽ 469) P-wave Duration (ms) 40 80 90 100 110 120 130 140 150 160 170
No. of Cases (%) 1 (⬍1%) 22 (5%) 44 (9%) 155 (33%) 44 (9%) 159 (34%) 23 (5%) 14 (3%) 2 (⬍1%) 4 (⬍1%) 1 (⬍1%)
mended a ⬍100-ms cutoff for the top normal value. One publication, among the most authoritative, represented a dichotomy of opinions by recommending 100 and 110 ms in the same paragraph.5 If we had used a P wave of 100 ms as the top normal cut-off value in this reevaluation series of outpatients who were presumably younger and could be considered “less sick,” the IAB prevalence, instead of being understandably somewhat lower, would have increased to 86%. Conversely, selecting a value higher than the mode, although reasonable, could perhaps allow for more falsenegative findings (9% prevalence with a 130-ms cut-off value).13 The prevalence of IAB even when a P wave ⱖ120 ms was used in this outpatient cohort remained high (43%, as previously reported)11; hence, the pandemic reference even under the most erudite standards. We have also consistently found that the mode P-wave duration in our investigations was 120 ms, and, for increased specificity, we have certainly used this measurement for the diagnosis of IAB.6 – 8,10,11 Although our purpose has strictly not been to challenge the World Health Organization (or any) guideline, nor to replace a diagnostic criterion, most standardized 12-lead electrocardiographic tracings use 10 ms at 25 mm/s, a recording that equals 1/4 mm. As such, measuring the P-wave durations in 40-ms multiples (1 mm on the ECG), for example, could be more practical when a P wave of ⱖ120 ms (3 mm on the ECG) is used for the diagnosis of IAB at the bedside.9 We, however, acknowledge that even the widest P wave taken from a tracing of a standard bedside ECG sometimes cannot be accurately established by manual estimation, especially when of low or very low voltage. Neither the true onset nor offset of the P wave can perhaps be so determined even under magnification. Moreover, P-wave durations measured in this manner may only rarely precisely correlate with the actual total atrial activation time recorded during electro-
937
physiologic evaluations. However, altering the sweep speed or gain of the ECG in an attempt to achieve optimal results for the diagnosis of IAB could be impractical at the bedside, where the inimitable essence of this inexpensive, quick, and efficient clinical tool is most desired.9 The current recommendations for the top normal interatrial conduction time are, however, based on references to earlier textbooks and other publications that often did not involve original work and, therefore, probably require reevaluation, particularly epidemiologists who could have more realistic normal standards. 1. Bayes de Luna A. Electrocardiographic alterations due to atrial pathology. In: Clinical Electrocardiography: A Textbook. New York: Futura; 1998:169 –171. 2. Ariyarajah V, Apiyasawat S, Puri P, Spodick DH. Specific electrocardiographic markers of P-wave morphology in interatrial block. J Electrocardiol, in press. 3. Waldo AL, Wit AL. Mechanisms of cardiac arrhythmias and conduction disturbances. Part 4. Rhythm and conduction disturbances. In: Fuster V, Alexander RW, O’Rourke RA, eds. Hurst’s The Heart. 10th Edition. New York: McGraw-Hill, 2000:757–796. 4. Slotwiner DJ, Stein KM, Markowitz SM, Mittal SM, Scheiner M, Christini DJ, Lerman BB. Electrophysiology of cardiac arrythmias. Section IV. Disorders of rhythm and conduction. In: Rosendorff C, ed. Essential Cardiology: Principles and Practice. Philadelphia: WB Saunders, 2001:285–308. 5. MacFarlane PW. Atrial enlargement and overload. In: MacFarlane PW, Veitch Lawrie TD, eds. Comprehensive Electrocardiology: Theory and Practice in Health and Disease, 1st ed. Vol 1. Elmsford, NY: Pergamon Press; 1989:662– 664. 6. Ariyarajah V, Puri P, Kranis M, Wilner DA, Spodick DH. Prevalence of interatrial block in the Program of All-inclusive Care for the Elderly (PACE). Am J Ger Cardiol, 2006;15:174 –177. 7. Asad N, Spodick DH. Prevalence of interatrial block in a general hospital population. Am J Cardiol 2003;91:609 – 610. 8. Jairath UC, Spodick DH. Exceptional prevalence of interatrial block in a general hospital population. Clin Cardiol 2001;24:548 –550. 9. Ariyarajah V, Apiyasawat S, Spodick DH. Optimal P-wave duration for bedside diagnosis of interatrial block. Ann Noninvas Electrocardiol, 2006;11:259 –262. 10. Goyal SB, Spodick DH. Electromechanical dysfunction of the left atrium associated with interatrial block. Am Heart J 2001;142:823– 827. 11. Frisella ME, Spodick DH. Confirmation of the prevalence and importance of a 12-lead investigation for diagnosis. Am J Cardiol 2005;96: 696 – 697. 12. Willems JL, Robles de Medina EO, Bernard R, Coumel P, Fisch C, Krikler D, Mazur NA, Meijler FL, Mogensen L, Mort P, et al, for the World Health Organizational/International Society and Federation for Cardiology Task Force Ad Hoc Committee. Criteria for intraventricular conduction disturbances and pre-excitation. J Am Coll Cardiol 1985;5:1261–1275. 13. Ascione R, Caputo M, Calori G, Lloyd CT, Underwood MJ, Angelini GD. Predictors of atrial fibrillation after conventional and beating heart coronary surgery. Circulation 2000;102:1530 –1535.