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Community screening for left ventricular hypertrophy in patients with hypertension using hand-held echocardiography
Community Screening for Left Ventricular Hypertrophy in Patients with Hypertension Using Hand-held Echocardiography Roxy Senior, MD, DM, FRCP (Lond), FESC, FACC, Gavin Galasko, MRCP, Michael Hickman, MRCP, Paramjit Jeetley, MRCP, and Avijit Lahiri, MB,BS, MSc, MRCP, FACC, FESC, Harrow, United Kingdom
Left ventricular (LV) hypertrophy (LVH) confers increased cardiovascular risk on patients with hypertension. Echocardiography using new handheld devices might allow community-based costeffective screening for LVH in a targeted hypertensive population. Thus, the aim of this study was to test the validity of hand-held ultrasound devices to screen for LVH in the community. Accordingly, 189 patients with hypertension attending a community-based heart failure screening program underwent echocardiography by both hand-held and standard devices by an experienced echocardiographer. LVH was defined as LV mass index >134 g.mⴚ2 for men and >110 g.mⴚ2 for women
Systemic hypertension is a growing health care
problem affecting up to 25% of adults in the Western World.1 It is a major cause of acute coronary syndromes, stroke, and heart failure.1,2 Presence of left ventricular (LV) hypertrophy (LVH) in a patient with hypertension confers increased risk for development of subsequent cardiovascular event.3 The combination of hypertension and LVH results in a 5- to 10-fold increase in the risk of heart failure developing.4 Thus, in patients with hypertension and no other complications, LVH may be considered a surrogate marker of overt cardiovascular disease.5 The use of echocardiography to assess LVH and LV mass has further prognostic value.6,7 Cardiovascular events are increased in patients with increased LV mass on echocardiography.8 Furthermore, regression of LVH and LV mass in patients with hypertension after antihypertensive therapy has been shown to improve prognosis independent of blood pressure reduction.9,10 Initiation of pharmacologic therFrom the Department of Cardiovascular Medicine, Northwick Park Hospital. Supported in part by a grant from the Cardiac Research Fund. Reprint requests: Roxy Senior, MD, DM, FRCP (Lond), FESC, FACC, Department of Cardiovascular Medicine, Northwick Park Hospital, Watford Rd, Harrow, Middlesex, HAI 3UJ United Kingdom (E-mail: [email protected]). 0894-7317/$30.00 Copyright 2004 by the American Society of Echocardiography. doi:10.1067/j.echo.2003.09.013
56
using the Devereux-modified American Society of Echocardiography cube equation. No significant differences were noted between the 2 devices in the measurement of LV wall thickness or LV mass index. Agreement for estimation of LVH between the 2 devices was 86% ( ⴝ 0.63). The sensitivity, specificity, and positive and negative predictive values of the hand-held device for predicting LVH were 72%, 91%, 73%, and 90%, respectively. Thus, hand-held echocardiography devices accurately assessed LVH and may be used for communitybased screening for LVH in targeted patients with hypertension. (J Am Soc Echocardiogr 2004;17: 56-61.)
apy in a patient with borderline hypertension requires demonstration of target organ involvement, one of which is the presence of LVH.11 Thus, screening for LVH in a patient with hypertension has both therapeutic and prognostic implications. Electrocardiography (ECG) has been shown to be less accurate than echocardiography for the diagnosis of LVH.12 The advent of hand-held ultrasound systems, which has been shown to accurately assess LV function, may allow rapid screening for LVH in patients with hypertension in the community.13 The aim of the study was to compare the accuracy of the hand-held ultrasound device for assessment of LVH with the standard echocardiography system for patients with hypertension in the community.
METHODS Patients From a cohort of people from the community who were invited to take part in the screening for heart failure, patients with hypertension were identified.14 Patients with hypertension were identified from the general practitioners’ registry. All attending patients had been chosen at random from the computer records of 7 geographically and socioeconomically representative general practices in Harrow, United Kingdom. All patients were on antihyper-
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device and then on the standard echocardiography device, with all measurements from the hand-held device obtained before using the standard system. The hand-held device did not allow storing of images. Images from the standard system were, however, stored as digital loops 4 cardiac cycles in length onto optical disk, with measurements taken at least 1 month later without knowledge of the hand-held device results. Echocardiographic Measurements
Figure 1 Hand-held echocardiography device.
tensive therapy. The study was approved by the local research ethical committee. All patients underwent both hand-held and standard echocardiography. Attending patients had their resting heart rate and blood pressure measured as the average of 2 measurements 5 minutes apart after 10 and 15 minutes, respectively, in the reclining position. ECG Each patient had a baseline ECG performed. LVH was diagnosed if either of the following 2 criteria were met: (1) the sum of the amplitudes of the S wave in V1 and the R wave in V5 or V6 was ⱖ35 mm (Sokolow-Lyon criteria); or (2) the amplitude of the R wave in lead aVL was ⬎11 mm. These 2 criteria give high sensitivity and specificity, respectively, for detecting LVH.15 Echocardiography Each patient underwent hand-held echocardiography (OptiGo, Philips, Eindhoven, Netherlands), and standard echocardiography (Sonos 4500, Phillips). The portable device consisted of a base unit (27 ⫻ 21 ⫻ 7 cm), 2.5-MHz phased-array transducer, and battery (Figure 1), giving digital 2-dimensional fundamental imaging on a 5.5-in liquid crystal display. Linear measurements were taken using calipers using freeze-frame and scrolling capabilities. Total weight was 3 kg. The standard machine used a 1.8/3.6-MHz second-harmonic fusion imaging transducer and a 15-in screen, weighed 214 kg, and had external dimensions of 151 ⫻ 103 ⫻ 63 cm. All analyses on this machine were taken using second-harmonic imaging. Two-dimensional echocardiography was performed and analyzed by 1 investigator (G.G.), a cardiology registrar, who had undergone an intensive 6-month training program in performing and analyzing more than 300 echocardiography studies under the supervision of an expert echocardiographer (R.S.) before commencement of the study. Images were obtained first on the hand-held
LV end-diastolic chamber dimension (LVEDD), and enddiastolic wall thickness of the interventricular septum (IVST) and posterior walls (PWT) were obtained in the short-axis parasternal view at the papillary muscle level for both echocardiographic systems according to the recommendations of the American Society of Echocardiography (ASE).16 LV mass was calculated using Devereux-modified ASE equation: 0.80 {1.04 [(IVST ⫹ PWT ⫹ LVEDD)3 ⫺ LVEDD3]} ⫹ 0.6 gm.17 LV mass index (LVMI) was calculated by dividing LVMI by body surface area (derived from the height and weight).18 LVH was considered to be present when LVMI exceeded 134 gm2/m2 and 110 gm2/m2 for men and women, respectively.19 Interobserver variability for LV wall thickness and LV mass was assessed on a separate day. Statistical Analysis All categorical variables were expressed as proportions or percentages and all continuous variables as mean ⫾ SD. All corresponding measurements between the hand-held and standard devices were assessed by linear regression analysis for correlation coefficient, Bland-Altman plots for 95% limits of agreement, and the paired-samples t test for overall differences. The sensitivity, specificity, and positive and negative predictive value and overall accuracy, including values of agreement (⬍0.40 ⫽ poor, 0.40-0.59 ⫽ moderate, 0.60-0.79 ⫽ good, and ⬎0.80 ⫽ excellent), for the hand-held device to assess clinically significant LVH was assessed. The chi-square test was used to compare categorical groups. Data were analyzed using software (Analyse-it for Microsoft Excel, Version 1.48, Analyse-it Software, Ltd, Leeds, United Kingdom).
RESULTS Patients From a population of 562 people screened, 189 patients were known to have hypertension. Table 1 outlines the demography of the 189 patients. Hemodynamics The mean heart rate was 70 ⫾ 15 bpm and the mean systolic and diastolic blood pressures were 144 ⫾ 21 mm Hg and 85 ⫾ 9 mm Hg, respectively.
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Table 1 Patient demography 67 ⫾ 10 107 (57%) 132 (70%) 51 (27%) 5 (3%) 1 (0.5%) 85 (45%) 81 (43%) 72 (38%) 56 (30%) 18 (10%) 11 (6%) 2 (1%) 144 ⫾ 21 85 ⫾ 9 70 ⫾ 15 27 ⫾ 5
Age (y) Male, n (%) Ethnicity: Caucasian South Asian Africo-Caribbean Other Medications: Calcium antagonists Diuretics ACE-Inhibitors Beta-blockers Alpha-blockers A-II antagonists Other Systolic BP (mm Hg) Diastolic BP (mm Hg) Heart rate (bpm) Body mass index ACE, Angiotensin-converting enzyme; BP, blood pressure.
Table 2 Echocardiographic values using hand-held and standard echocardiography
Hand-held Standard 95% Limits of agreement P values
LVEDD (mm)
IVS (mm)
PWT (mm)
51.2 51.7 ⫾8.3 0.12
10.0 10.1 ⫾2.3 0.3
9.3 9.1 ⫾2.9 0.08
Figure 2 Correlation between hand-held and standard echocardiography (Echo) devices for assessment of left ventricular mass index (LVMI).
LVEDD, Left ventricular end-diastolic dimension; IVS, Interventricular septal thickness; PWT, posterior wall thickness.
Echocardiography Complete measurements were obtained in 180 (95%) patients with the hand-held device and 185 (98%) patients with standard echocardiography. Complete data with both devices were obtained in 179 patients. Data on the 179 patients were analyzed. No significant differences were noted between the hand-held and standard echocardiographic devices for LVEDDs, IVST, and PWT (Table 2). The LVMI obtained by standard echocardiography was 105 ⫾ 14 gm/m2 and that obtained by hand-held device was 102 ⫾ 13 gm/m2 (P ⫽ .5). LVH was present in 46 (26%) patients as assessed by standard echocardiography. Figure 2 shows the correlation between the 2 devices for the assessment of LVMI (r ⫽ 0.78). Figure 3 shows the Bland-Altman method of comparing LVMI between the 2 devices. The 95% confidence intervals were ⫹38 gm/m2 and ⫺40 gm/m2. Figure 4 shows the concordance between the 2 devices for assessment of LVH. There was an agreement of 86% ( ⫽ 0.63, 95% confidence interval, 0.50-0.7). Sensitivity, specificity, and positive and negative predictive value for the prediction of LVH by hand-held system compared with standard sys-
Figure 3 Bland-Altman plot comparing left ventricular mass index by hand-held and standard echocardiography devices.
tem were 72%, 91%, 73%, and 90%, respectively. Accuracy of hand-held device for predicting LVH was 86%. Interobserver Variability Differences between 2 observers (M.H. and P.J. with similar experience as G.G.) for IVST, PWT, and LV mass were 4.5%, 3.2%, and 6.5%, respectively, using the hand-held device. ECG In all, 37 patients were found to have LVH on ECG. Sensitivity, specificity, positive predictive value, negative predictive values, and accuracy were 35%,
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Figure 4 Agreement between hand-held and standard echocardiography in predicting left ventricular hypertrophy (LVH). Agreement ⫽ 86% ( ⫽ 0.63, 95% confidence interval 0.50-0.76).
Figure 5 Agreement between electrocardiography (ECG) and standard echocardiography in predicting left ventricular hypertrophy (LVH). Agreement ⫽ 63% ( ⫽ 0.22).
85%, 46%, 70%, and 72%, respectively, for predicting LVH as assessed by standard echocardiography (Figure 5).
DISCUSSION This study clearly showed that the hand-held device may be reliably used to assess LVH for patients with hypertension. Indeed, this is the first study that screened people from the community for LVH. In another study by Vourvouri et al,20 which evaluated patients with hypertension visiting the outpatient clinic, the reliability of the hand-held device for the assessment of LVH in patients with hypertension was similarly shown. The positive and negative
Senior et al 59
predictive values for LVH obtained in our study were similar to those obtained by Vourvouri et al.20 These studies clearly validate hand-held devices for ruling out patients with LVH in a hypertensive population. Our study further highlighted the poor accuracy of ECG for detecting LVH. LVH has been shown to confer incremental and independent cardiovascular risk over and above blood pressure measurements.6,7 Indeed, patterns of LVH further influences outcome. Concentric LVH has the worst outcome compared with eccentric LVH and concentric remodeling.21 It has also been shown in several studies that regression of LVH improves prognosis in patients with hypertension, a benefit which is above and beyond control of the blood pressure.22 Although patients with hypertension who have demonstrable target organ damage do not benefit from additional assessment of LVH, patients with hypertension and no complications may benefit from assessment of LVH.23 Presence of LVH in these patients should prompt physicians to start more aggressive antihypertensive therapy. Though it is recognized that all patients with hypertension should have their blood pressure controlled aggressively, presence of LVH calls for closer supervision. Furthermore, although most antihypertensive medications reduce LVH, some are more potent than others and presence of LVH may influence the choice of antihypertensive.24 Assessment of LVH is also strongly recommended in patients with hypertension and associated heart disease,25 and in patients with borderline hypertension who–in the absence of LVH–may not require pharmacologic therapy. Presence of LVH in this group of patients will triage them into pharmacologic therapy.25-27 Indeed, limited echocardiography was recommended for screening for LVH in routine evaluation of patients with hypertension.28,29 However, despite superior evaluation of LVH with echocardiography, primary care physicians continue to rely on ECG for assessment of LVH. This is because standard echocardiography is mostly inaccessible; when accessible, there is a waiting period and technology is expensive. Hand-held echocardiography provides similar accuracy to standard echocardiography but is readily accessible, occupies very little space, and is inexpensive. This will allow routine echocardiographic assessment in all patients with hypertension but without complications. It will provide the clinician with immediate important prognostic information and risk stratification and, therefore, improve treatment. Study Limitations Hand-held echocardiography was performed by only 1 operator using only 1 device. However,
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observer variability in this study using the same device was assessed by 2 other physicians and it was excellent. Furthermore, Vourvouri et al20 showed similar results with a different hand-held device in a different population. Second, because of the lack of M-mode capability on the hand-held device, measurements were done with calipers on both machines, potentially reducing measurement accuracy. Third, the amount of training required before being fully capable of using such devices has not been addressed in this study. A cardiology trainee (G.G.), who performed all the echocardiography in this study, had been intensively trained for a 6-month period by an expert echocardiographer (R.S.) before commencing the study. Thus, the results of the study are only applicable to similarly trained individuals. This is an important point, as poorly trained individuals performing screening echocardiography using portable devices may not yield the same result. Physicians in primary care should undergo targeted training before performing bedside echocardiography. Patients with borderline LVH may be referred to the hospital for further assessment. However, the ASE recommends that users of hand-held echocardiographic devices be at least at level 1 of training, and trained up to level II to independently perform and interpret hand-held device studies. Conclusion Hand-held ultrasound devices may be reliably used by trained physicians to assess LVH for patients with hypertension where indicated.
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REFERENCES 1. American Heart Association. 2002 Heart and stroke statistical update. Dallas (TX): American Heart Association; 2001. 2. Levy D, Larson MG, Vasan RS, Kannel WB, Ho KKL. The progression from hypertension to congestive heart failure. JAMA 1996;275:1557-62. 3. Kannel WB, Gordon T, Castelli WP, Margolis JR. Electrocardiographic left ventricular hypertrophy and risk of coronary heart disease: the Framingham study. Ann Intern Med 1970; 72:813-22. 4. Sundstro¨m J, Lind L, Arnlo¨v J, Zethelius B, Andre´n B, Lithell HO. Echocardiographic and electrocardiographic diagnoses of left ventricular hypertrophy predict mortality independently of each other in a population of elderly men. Circulation 2001;103:2346-51. 5. Devereux RB, Alderman MH. Role of preclinical cardiovascular disease in the evolution from risk factor exposure to development of morbid events. Circulation 1993;88:1444-55. 6. Casale PN, Devereux RB, Milner M, Zullo G, Harshfield GA, Pickering TG, et al. Value of echocardiographic measurement of left ventricular hypertrophy in essential hypertensive men. Ann Intern Med 1986;105:173-8. 7. Levy D, Garrison RJ, Savage DD, Kannel WB, Castelli WP. Prognostic implications of echocardiographically determined
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left ventricular mass in the Framingham heart study. N Engl J Med 1990;322:1561-6. Koren MJ, Devereux RB, Casale PN, Savage DD, Laragh JH. Relation of left ventricular mass and geometry to morbidity and mortality in uncomplicated essential hypertension. Ann Intern Med 1991;117:831-6. Muiesan ML, Salvetti M, Rizzoni D, Castellano M, Donato F, Agabiti-Rosei E. Association of change in left ventricular mass with prognosis during long-term antihypertensive treatment. J Hypertens 1995;13:1091-5. Verdecchia P, Schillaci G, Borgioni C, Ciucci A, Gattobigio R, Zampi I, et al. Prognostic significance of serial changes in left ventricular mass in essential hypertension. Circulation 1998; 97:48-54. Guidelines Subcommittee of the World Health Organization International Society of Hypertension (WHO-ISH) Mild Hypertension Committee. 1999 World Health Organization International Society of Hypertension guidelines for management of hypertension. J Hypertens 1999;17:151-83. Norman JE, Levy D, Campbell G, Bailey JJ. Improved detection of echocardiographic left ventricular hypertrophy using a new electrocardiographic algorithm. J Am Coll Cardiol 1993; 21:1680-6. Galasko GIW, Lahiri A, Senior R. Portable echocardiography: an innovative tool in screening for cardiac abnormalities in high-risk and low-risk members of the community. Eur J Echocardiogr 2003;4:119-27. Galasko GIW, Senior R, Lahiri A. Left ventricular systolic dysfunction: its community prevalence, aetiology and underlying risk factors in a multi-ethnic community [abstract]. Eur Heart J 2001;22:712. Alexander RW, Schlant RC, Fuster V. Hurst’s the heart. 9th ed. New York: McGraw-Hill; 1998. p 370. Schiller NB, Shah PM, Crawford M, DeMaria A, Devereux R, Feigenbaum H, et al. Recommendations for quantiation of the left ventricle by two-dimensional echocardiography. J Am Soc Echocardiogr 1989;2:358-67. Schillaci G, Verdecchia P, Borgioni C, Ciucci A, Guerrieri M, Zampi I. Improved electrocardiographic diagnosis of left ventricular hypertrophy. Am J Cardiol 1994;74:714-9. DuBois D, DuBois EF. A formula to estimate the approximate surface area if height and weight be known. Arch Intern Med 1916;17:863-71. Devereux RB. Detection of left ventricular hypertrophy by M-mode echocardiography: anatomic validation, standardization, and comparison to other methods. Hypertension 1987; 9:9-26. Vourvouri EC, Poldermans D, Schinkel AFL, Koroleva LY, Sozzi FB, Parharidis GE, et al. Left ventricular hypertrophy screening using a hand-held ultrasound device. Eur Heart J 2002;23:1516-21. Ganau A, Devereux RB, Roman MJ, de Simone G, Pickering T, Sal PS, et al. Patterns of left ventricular hypertrophy and geometric remodeling in essential hypertension. J Am Coll Cardiol 1992;19:1550-8. Mathew J, Sleight P, Lonn E, Johnstone D, Pogue J, Yi Q, et al. Reduction of cardiovascular risk by regression of electrocardiographic markers of left ventricular hypertrophy by the angiotensin converting enzyme inhibitor, ramipril. Circulation 2001;104:1615-21. The sixth report of the Joint National Committee on prevention, detection, evaluation and treatment of high blood pressure. Arch Intern Med 1997;157:2413-46.
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24. Dahlof B, Pennert K, Hansson L. Reversal of left ventricular hypertrophy in hypertensive patients: a metaanalysis of 109 treatment studies. Am J Hypertens 1992;5:95-110. 25. de Simone G, Ganau A, Verdecchia P, Devereux RB. Echocardiography in arterial hypertension: when, why and how? J Hypertens 1994;12:1129-36. 26. de Simone G, Schillaci G, Palmieri V, Devereux RB. Should all patients with hypertension have echocardiography? J Hum Hypertens 2000;14:417-21. 27. Abergel E, Chatellier G, Battaglia C, Menard J. Can echocar-
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diographic identify mildly hypertensive patients at high risk, left untreated based on current guidelines? J Hypertens 1999; 17:817-24. 28. Black HR, Weltin G, Jaffe CC. The limited echocardiogram: a modification of standard echocardiography for used in the routine evaluation of patients with systemic hypertension. Am J Cardiol 1991;67:1027-30. 29. Sheps SG, Frohlich ED. Limited echocardiography for hypertensive left ventricular hypertrophy. Hypertension 1997;29: 560-3.
Left ventricular (LV) hypertrophy (LVH) confers increased cardiovascular risk on patients with hypertension. Echocardiography using new handheld devices might allow community-based costeffective screening for LVH in a targeted hypertensive population. Thus, the aim of this study was to test the validity of hand-held ultrasound devices to screen for LVH in the community. Accordingly, 189 patients with hypertension attending a community-based heart failure screening program underwent echocardiography by both hand-held and standard devices by an experienced echocardiographer. LVH was defined as LV mass index >134 g.mⴚ2 for men and >110 g.mⴚ2 for women
Systemic hypertension is a growing health care
problem affecting up to 25% of adults in the Western World.1 It is a major cause of acute coronary syndromes, stroke, and heart failure.1,2 Presence of left ventricular (LV) hypertrophy (LVH) in a patient with hypertension confers increased risk for development of subsequent cardiovascular event.3 The combination of hypertension and LVH results in a 5- to 10-fold increase in the risk of heart failure developing.4 Thus, in patients with hypertension and no other complications, LVH may be considered a surrogate marker of overt cardiovascular disease.5 The use of echocardiography to assess LVH and LV mass has further prognostic value.6,7 Cardiovascular events are increased in patients with increased LV mass on echocardiography.8 Furthermore, regression of LVH and LV mass in patients with hypertension after antihypertensive therapy has been shown to improve prognosis independent of blood pressure reduction.9,10 Initiation of pharmacologic therFrom the Department of Cardiovascular Medicine, Northwick Park Hospital. Supported in part by a grant from the Cardiac Research Fund. Reprint requests: Roxy Senior, MD, DM, FRCP (Lond), FESC, FACC, Department of Cardiovascular Medicine, Northwick Park Hospital, Watford Rd, Harrow, Middlesex, HAI 3UJ United Kingdom (E-mail: [email protected]). 0894-7317/$30.00 Copyright 2004 by the American Society of Echocardiography. doi:10.1067/j.echo.2003.09.013
56
using the Devereux-modified American Society of Echocardiography cube equation. No significant differences were noted between the 2 devices in the measurement of LV wall thickness or LV mass index. Agreement for estimation of LVH between the 2 devices was 86% ( ⴝ 0.63). The sensitivity, specificity, and positive and negative predictive values of the hand-held device for predicting LVH were 72%, 91%, 73%, and 90%, respectively. Thus, hand-held echocardiography devices accurately assessed LVH and may be used for communitybased screening for LVH in targeted patients with hypertension. (J Am Soc Echocardiogr 2004;17: 56-61.)
apy in a patient with borderline hypertension requires demonstration of target organ involvement, one of which is the presence of LVH.11 Thus, screening for LVH in a patient with hypertension has both therapeutic and prognostic implications. Electrocardiography (ECG) has been shown to be less accurate than echocardiography for the diagnosis of LVH.12 The advent of hand-held ultrasound systems, which has been shown to accurately assess LV function, may allow rapid screening for LVH in patients with hypertension in the community.13 The aim of the study was to compare the accuracy of the hand-held ultrasound device for assessment of LVH with the standard echocardiography system for patients with hypertension in the community.
METHODS Patients From a cohort of people from the community who were invited to take part in the screening for heart failure, patients with hypertension were identified.14 Patients with hypertension were identified from the general practitioners’ registry. All attending patients had been chosen at random from the computer records of 7 geographically and socioeconomically representative general practices in Harrow, United Kingdom. All patients were on antihyper-
Journal of the American Society of Echocardiography Volume 17 Number 1
Senior et al 57
device and then on the standard echocardiography device, with all measurements from the hand-held device obtained before using the standard system. The hand-held device did not allow storing of images. Images from the standard system were, however, stored as digital loops 4 cardiac cycles in length onto optical disk, with measurements taken at least 1 month later without knowledge of the hand-held device results. Echocardiographic Measurements
Figure 1 Hand-held echocardiography device.
tensive therapy. The study was approved by the local research ethical committee. All patients underwent both hand-held and standard echocardiography. Attending patients had their resting heart rate and blood pressure measured as the average of 2 measurements 5 minutes apart after 10 and 15 minutes, respectively, in the reclining position. ECG Each patient had a baseline ECG performed. LVH was diagnosed if either of the following 2 criteria were met: (1) the sum of the amplitudes of the S wave in V1 and the R wave in V5 or V6 was ⱖ35 mm (Sokolow-Lyon criteria); or (2) the amplitude of the R wave in lead aVL was ⬎11 mm. These 2 criteria give high sensitivity and specificity, respectively, for detecting LVH.15 Echocardiography Each patient underwent hand-held echocardiography (OptiGo, Philips, Eindhoven, Netherlands), and standard echocardiography (Sonos 4500, Phillips). The portable device consisted of a base unit (27 ⫻ 21 ⫻ 7 cm), 2.5-MHz phased-array transducer, and battery (Figure 1), giving digital 2-dimensional fundamental imaging on a 5.5-in liquid crystal display. Linear measurements were taken using calipers using freeze-frame and scrolling capabilities. Total weight was 3 kg. The standard machine used a 1.8/3.6-MHz second-harmonic fusion imaging transducer and a 15-in screen, weighed 214 kg, and had external dimensions of 151 ⫻ 103 ⫻ 63 cm. All analyses on this machine were taken using second-harmonic imaging. Two-dimensional echocardiography was performed and analyzed by 1 investigator (G.G.), a cardiology registrar, who had undergone an intensive 6-month training program in performing and analyzing more than 300 echocardiography studies under the supervision of an expert echocardiographer (R.S.) before commencement of the study. Images were obtained first on the hand-held
LV end-diastolic chamber dimension (LVEDD), and enddiastolic wall thickness of the interventricular septum (IVST) and posterior walls (PWT) were obtained in the short-axis parasternal view at the papillary muscle level for both echocardiographic systems according to the recommendations of the American Society of Echocardiography (ASE).16 LV mass was calculated using Devereux-modified ASE equation: 0.80 {1.04 [(IVST ⫹ PWT ⫹ LVEDD)3 ⫺ LVEDD3]} ⫹ 0.6 gm.17 LV mass index (LVMI) was calculated by dividing LVMI by body surface area (derived from the height and weight).18 LVH was considered to be present when LVMI exceeded 134 gm2/m2 and 110 gm2/m2 for men and women, respectively.19 Interobserver variability for LV wall thickness and LV mass was assessed on a separate day. Statistical Analysis All categorical variables were expressed as proportions or percentages and all continuous variables as mean ⫾ SD. All corresponding measurements between the hand-held and standard devices were assessed by linear regression analysis for correlation coefficient, Bland-Altman plots for 95% limits of agreement, and the paired-samples t test for overall differences. The sensitivity, specificity, and positive and negative predictive value and overall accuracy, including values of agreement (⬍0.40 ⫽ poor, 0.40-0.59 ⫽ moderate, 0.60-0.79 ⫽ good, and ⬎0.80 ⫽ excellent), for the hand-held device to assess clinically significant LVH was assessed. The chi-square test was used to compare categorical groups. Data were analyzed using software (Analyse-it for Microsoft Excel, Version 1.48, Analyse-it Software, Ltd, Leeds, United Kingdom).
RESULTS Patients From a population of 562 people screened, 189 patients were known to have hypertension. Table 1 outlines the demography of the 189 patients. Hemodynamics The mean heart rate was 70 ⫾ 15 bpm and the mean systolic and diastolic blood pressures were 144 ⫾ 21 mm Hg and 85 ⫾ 9 mm Hg, respectively.
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Table 1 Patient demography 67 ⫾ 10 107 (57%) 132 (70%) 51 (27%) 5 (3%) 1 (0.5%) 85 (45%) 81 (43%) 72 (38%) 56 (30%) 18 (10%) 11 (6%) 2 (1%) 144 ⫾ 21 85 ⫾ 9 70 ⫾ 15 27 ⫾ 5
Age (y) Male, n (%) Ethnicity: Caucasian South Asian Africo-Caribbean Other Medications: Calcium antagonists Diuretics ACE-Inhibitors Beta-blockers Alpha-blockers A-II antagonists Other Systolic BP (mm Hg) Diastolic BP (mm Hg) Heart rate (bpm) Body mass index ACE, Angiotensin-converting enzyme; BP, blood pressure.
Table 2 Echocardiographic values using hand-held and standard echocardiography
Hand-held Standard 95% Limits of agreement P values
LVEDD (mm)
IVS (mm)
PWT (mm)
51.2 51.7 ⫾8.3 0.12
10.0 10.1 ⫾2.3 0.3
9.3 9.1 ⫾2.9 0.08
Figure 2 Correlation between hand-held and standard echocardiography (Echo) devices for assessment of left ventricular mass index (LVMI).
LVEDD, Left ventricular end-diastolic dimension; IVS, Interventricular septal thickness; PWT, posterior wall thickness.
Echocardiography Complete measurements were obtained in 180 (95%) patients with the hand-held device and 185 (98%) patients with standard echocardiography. Complete data with both devices were obtained in 179 patients. Data on the 179 patients were analyzed. No significant differences were noted between the hand-held and standard echocardiographic devices for LVEDDs, IVST, and PWT (Table 2). The LVMI obtained by standard echocardiography was 105 ⫾ 14 gm/m2 and that obtained by hand-held device was 102 ⫾ 13 gm/m2 (P ⫽ .5). LVH was present in 46 (26%) patients as assessed by standard echocardiography. Figure 2 shows the correlation between the 2 devices for the assessment of LVMI (r ⫽ 0.78). Figure 3 shows the Bland-Altman method of comparing LVMI between the 2 devices. The 95% confidence intervals were ⫹38 gm/m2 and ⫺40 gm/m2. Figure 4 shows the concordance between the 2 devices for assessment of LVH. There was an agreement of 86% ( ⫽ 0.63, 95% confidence interval, 0.50-0.7). Sensitivity, specificity, and positive and negative predictive value for the prediction of LVH by hand-held system compared with standard sys-
Figure 3 Bland-Altman plot comparing left ventricular mass index by hand-held and standard echocardiography devices.
tem were 72%, 91%, 73%, and 90%, respectively. Accuracy of hand-held device for predicting LVH was 86%. Interobserver Variability Differences between 2 observers (M.H. and P.J. with similar experience as G.G.) for IVST, PWT, and LV mass were 4.5%, 3.2%, and 6.5%, respectively, using the hand-held device. ECG In all, 37 patients were found to have LVH on ECG. Sensitivity, specificity, positive predictive value, negative predictive values, and accuracy were 35%,
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Figure 4 Agreement between hand-held and standard echocardiography in predicting left ventricular hypertrophy (LVH). Agreement ⫽ 86% ( ⫽ 0.63, 95% confidence interval 0.50-0.76).
Figure 5 Agreement between electrocardiography (ECG) and standard echocardiography in predicting left ventricular hypertrophy (LVH). Agreement ⫽ 63% ( ⫽ 0.22).
85%, 46%, 70%, and 72%, respectively, for predicting LVH as assessed by standard echocardiography (Figure 5).
DISCUSSION This study clearly showed that the hand-held device may be reliably used to assess LVH for patients with hypertension. Indeed, this is the first study that screened people from the community for LVH. In another study by Vourvouri et al,20 which evaluated patients with hypertension visiting the outpatient clinic, the reliability of the hand-held device for the assessment of LVH in patients with hypertension was similarly shown. The positive and negative
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predictive values for LVH obtained in our study were similar to those obtained by Vourvouri et al.20 These studies clearly validate hand-held devices for ruling out patients with LVH in a hypertensive population. Our study further highlighted the poor accuracy of ECG for detecting LVH. LVH has been shown to confer incremental and independent cardiovascular risk over and above blood pressure measurements.6,7 Indeed, patterns of LVH further influences outcome. Concentric LVH has the worst outcome compared with eccentric LVH and concentric remodeling.21 It has also been shown in several studies that regression of LVH improves prognosis in patients with hypertension, a benefit which is above and beyond control of the blood pressure.22 Although patients with hypertension who have demonstrable target organ damage do not benefit from additional assessment of LVH, patients with hypertension and no complications may benefit from assessment of LVH.23 Presence of LVH in these patients should prompt physicians to start more aggressive antihypertensive therapy. Though it is recognized that all patients with hypertension should have their blood pressure controlled aggressively, presence of LVH calls for closer supervision. Furthermore, although most antihypertensive medications reduce LVH, some are more potent than others and presence of LVH may influence the choice of antihypertensive.24 Assessment of LVH is also strongly recommended in patients with hypertension and associated heart disease,25 and in patients with borderline hypertension who–in the absence of LVH–may not require pharmacologic therapy. Presence of LVH in this group of patients will triage them into pharmacologic therapy.25-27 Indeed, limited echocardiography was recommended for screening for LVH in routine evaluation of patients with hypertension.28,29 However, despite superior evaluation of LVH with echocardiography, primary care physicians continue to rely on ECG for assessment of LVH. This is because standard echocardiography is mostly inaccessible; when accessible, there is a waiting period and technology is expensive. Hand-held echocardiography provides similar accuracy to standard echocardiography but is readily accessible, occupies very little space, and is inexpensive. This will allow routine echocardiographic assessment in all patients with hypertension but without complications. It will provide the clinician with immediate important prognostic information and risk stratification and, therefore, improve treatment. Study Limitations Hand-held echocardiography was performed by only 1 operator using only 1 device. However,
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observer variability in this study using the same device was assessed by 2 other physicians and it was excellent. Furthermore, Vourvouri et al20 showed similar results with a different hand-held device in a different population. Second, because of the lack of M-mode capability on the hand-held device, measurements were done with calipers on both machines, potentially reducing measurement accuracy. Third, the amount of training required before being fully capable of using such devices has not been addressed in this study. A cardiology trainee (G.G.), who performed all the echocardiography in this study, had been intensively trained for a 6-month period by an expert echocardiographer (R.S.) before commencing the study. Thus, the results of the study are only applicable to similarly trained individuals. This is an important point, as poorly trained individuals performing screening echocardiography using portable devices may not yield the same result. Physicians in primary care should undergo targeted training before performing bedside echocardiography. Patients with borderline LVH may be referred to the hospital for further assessment. However, the ASE recommends that users of hand-held echocardiographic devices be at least at level 1 of training, and trained up to level II to independently perform and interpret hand-held device studies. Conclusion Hand-held ultrasound devices may be reliably used by trained physicians to assess LVH for patients with hypertension where indicated.
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