|
| HOME | SUBSCRIPTIONS | CURRENT ISSUE | PAST ISSUES | CARDIOSOURCE | SEARCH | HELP | FEEDBACK |
|
|
|
|||||||||
|
|||||||||||
|
J Am Coll Cardiol, 2003; 42:873-879, doi:10.1016/S0735-1097(03)00827-1 © 2003 by the American College of Cardiology Foundation |
* Department of Cardiological Sciences, St. George's Hospital Medical School, London, United Kingdom
Service of Cardiology, Juan Canalejo Hospital, A Coruña, Spain
Manuscript received September 13, 2002; revised manuscript received January 15, 2003, accepted February 10, 2003.
* Reprint requests and correspondence: Dr. Perry M. Elliott, Department of Cardiological Sciences, St. George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, United Kingdom.
pelliott{at}sghms.ac.uk
 |
Abstract |
|---|
 Top Abstract MethodsResultsDiscussionReferences |
|---|
BACKGROUND: It has been suggested that NSVT is only of prognostic importance in patients with hypertrophic cardiomyopathy (HCM) when repetitive, prolonged, or associated with symptoms.
METHODS: We studied 531 patients with HCM (323 male, 39 ± 15 years). All underwent ambulatory electrocardiogram monitoring (41 ± 11 h).
RESULTS: A total of 104 patients (19.6%) had NSVT. The proportion of patients with NSVT increased with age (p = 0.008). Maximum left ventricular wall thickness and left atrial size were greater in patients with NSVT. Mean follow-up was 70 ± 40 months. Sixty-eight patients died, 32 from sudden cardiac death (SCD). Twenty-one patients received an implantable cardioverter defibrillator (ICD). There were four appropriate ICD discharges. In patients 
30 years (but not >30), five-year freedom from sudden death was lower in those with NSVT (77.6% [95% confidence interval (CI): 59.8 to 95.4] vs. 94.1% [95% CI: 90.2 to 98.0]; p = 0.003). There was no relation between the duration, frequency, or rate of NSVT runs and prognosis at any age. The odds ratio of sudden death in patients 30 years of age with NSVT was 4.35 (95% CI: 1.54 to 12.28; p = 0.006) compared with 2.16 (95% CI: 0.82 to 5.69; p = 0.1) in patients >30 years of age.
CONCLUSIONS: Non-sustained ventricular tachycardia is associated with a substantial increase in sudden death risk in young patients with HCM. A relation between the frequency, duration, and rate of NSVT episodes could not be demonstrated.
| ||||||||||||||
|
Methods |
|---|
|
TopAbstractMethodsResultsDiscussionReferences |
|---|
Electrocardiography.
Two-channel (CM1 on channel 1 and V2 on channel 2) 24 to 48 h (mean, 41 ± 11 h) ambulatory electrocardiogram monitoring was performed in all patients (Marquette Electronics, Milwaukee, Wisconsin). Non-sustained ventricular tachycardia was defined as three or more consecutive ventricular beats at a rate of 
120 beats/min, lasting for <30 s. One investigator (L.M.) reviewed all the studies, identifying and printing all episodes of NSVT on 25 mm/s speed paper, including the three beats immediately preceding each episode. The same investigator (L.M.), unaware of the clinical, echocardiographic, and follow-up data, made the following measurements for each episode of NSVT: 1) number of consecutive ventricular beats; 2) rate of the VT; and 3) the number of runs during each recording.
Echocardiography. Two-dimensional and M-mode echocardiography were performed using standard methods (9). In brief, end-diastolic LV wall thickness was recorded at mitral valve and papillary muscle level in the anterior and posterior septum, and in the lateral and posterior LV wall using short-axis two-dimensional images. Anterior and posterior wall thickness at the apex was measured in the two-chamber and short-axis apical views. Left ventricular outflow tract velocities were measured using continuous-wave Doppler, and LV outflow tract gradients were calculated using the modified Bernouilli equation (LV outflow tract gradient = 4 x [LV outflow tract velocity]2).
Exercise testing. Patients were exercised to exhaustion on a treadmill using the Bruce or modified Bruce protocols (1988 to 1994), or on an upright bicycle ergometer (Sensormedics ergometrics 800S, Bitz, Germany) using an incremental ramp protocol (1994 onwards). Blood pressure was measured by auscultation of the brachial artery during deflation of a mercury sphygmomanometer at rest, every minute during exercise and for the first 5 min of recovery. Blood pressure response to exercise was considered abnormal when systolic blood pressure failed to increase by more than 25 mm Hg from baseline, or when there was a decrease of more than 10 mm Hg from the maximum blood pressure during exercise (3,10).
Survival analysis. Follow-up started with the date of the initial Holter recorded at St. George's Hospital. Survival data were collected in routine clinic visits and where necessary by direct communication with patients and their attending physicians. Additional information was obtained using a written questionnaire sent to all patients' general practitioners. In order to assess the influence of amiodarone on the relation between NSVT and prognosis, patients who had received the drug for the majority (>50%) of their follow-up were compared with patients who had never taken the drug or who had received the drug for <50% of their follow-up period.
As previously described (3,4), for the end point classification, we considered sudden death a witnessed death within 1 h of new symptoms and nocturnal deaths with no antecedent history of worsening symptoms. Deaths preceded by new signs and/or symptoms of heart failure of more than 1 h duration and/or cardiogenic shock were considered as heart failure deaths. Deaths secondary to stroke, pulmonary or systemic embolism, or myocardial infarction were also considered as cardiovascular deaths.
Statistical analysis. SPSS for PC statistical program (SPSS Inc., Chicago, Illinois) was used for the analysis. Continuous variables are presented as mean ± SD. Student t test (paired or unpaired) was used to compare continuous variables in patients with and without NSVT. Mann-Whitney U test was used to compare NSVT characteristics in patients with and without events. Chi-square test was used to compare categorical variables. Log-rank test was used to compare survival curves from different groups. A multivariate Cox regression model was used to analyze the relation between NSVT and survival. A p value <0.05 was considered statistically significant.
|
Results |
|---|
|
TopAbstractMethodsResultsDiscussionReferences |
|---|
|
|
|
Treatments and interventional procedures. A total of 168 patients (31.6%) received amiodarone during their follow-up, and 92 (17.3%) were on amiodarone for 50% of their follow-up or more. Eleven of these 92 patients died (three sudden deaths, four cardiovascular cause, four noncardiovascular or unknown cause), two received an appropriate ICD discharge, and one received a cardiac transplant. The reasons for amiodarone therapy were supraventricular tachycardia (including paroxysmal atrial fibrillation), n = 26 (28.3%); sudden death prophylaxis, n = 40 (43.5%); and both supraventricular tachycardia and sudden death prophylaxis, n = 15 (16.3%). In the remaining 11 patients, amiodarone therapy had been started by referring physicians before their evaluation at St. George's Hospital.
Five-year cumulative survival for all-cause mortality, heart transplantation, or appropriate ICD discharge was 88.3% (95% CI: 85.0 to 91.6) in patients who had never taken amiodarone or who had taken the drug for <50% of follow-up and 91.5% (95% CI: 85.4 to 97.6) in patients who had taken amiodarone for the majority of follow-up (p = 0.6). The corresponding five-year cumulative survival estimates for sudden death were 93.9% (95% CI: 91.4 to 96.4) and 97.7% (95% CI: 94.6 to 100) (p = 0.1).
Myectomy (20 patients, 2 with NSVT), alcohol septal ablation (14 patients, 4 with NSVT), and dual chamber pacemaker implantation (36 patients, 8 with NSVT) were performed in patients with severe LV outflow tract obstruction for the treatment of severe symptoms refractory to medical therapy. Thirty patients (7 with NSVT) received a pacemaker for the treatment of conduction system disease or chronotropic incompetence. Five patients (2 with NSVT) underwent mitral valve replacement. An ICD was implanted in 21 patients considered to be at high risk for sudden death: four with previous ventricular fibrillation (none of them with NSVT on Holter) and 17 with two or more recognized risk factors of SCD (3 with NSVT on Holter).
NSVT and mortality. Forty-two (9.8%) of the 427 patients without NSVT, and 26 (25%) of the 104 patients with NSVT died (p = 0.0001). Of the 32 patients that died suddenly, thirteen had NSVT (p = 0.005). Five-year cumulative freedom from all-cause mortality, heart transplantation, or appropriate ICD discharge was 90.6% (95% CI: 87.5 to 93.7) in patients without NSVT and 82.3% (95% CI: 74.3 to 90.3) in those with NSVT (p = 0.001). Five-year cumulative freedom from sudden death was 95.6% (95% CI: 93.4 to 97.8) in patients without NSVT and 90.7% (95% CI: 84.4 to 97.0) in patients with NSVT (p = 0.003). The overall relative risk for sudden death in patients with NSVT was 2.8 (95% CI: 1.4 to 5.6), p = 0.005.
Nine of the 13 patients with NSVT who died suddenly had only one or two episodes in 48 h. The remaining patients had 6, 9, 31, and 69 episodes. In seven of the 13 patients, there were no more than three or four beats in the longest run, and only three patients had runs of more than five beats. There was no significant difference in any NSVT variable in patients with and without sudden death or all-cause mortality (Table 2).
|
30 mm. In 5 of the 13 patients with NSVT that died suddenly, there was no other risk factor for sudden death but the presence of NSVT. Two of them had a LV outflow tract >90 mm Hg. Two of the 28 patients with NSVT who received amiodarone for more than 50% of their follow-up died suddenly (one having stopped treatment three months before her death because of side effects), compared with 11 of the 76 patients with NSVT not receiving amiodarone, p = 0.5. Five-year sudden death discharge freedom was 96.3% (95% CI: 89.2 to 100) in amiodarone-treated patients with NSVT and 88.4% (95% CI: 80.2 to 96.6) in patients with NSVT not treated with amiodarone, p = 0.2.
There was 1 sudden death and 2 appropriate ICD discharges in the 64 patients without NSVT who received amiodarone for more than 50% of their follow-up, and 18 sudden deaths and two appropriate ICD discharges in the remaining 363 patients, p = 1. In patients without NSVT, five-year sudden death freedom was 98.3% (95% CI: 95.0 to 100) in amiodarone-treated patients and 95.1% (95% CI: 92.7 to 97.6) in patients not treated with amiodarone for the majority of follow-up, p = 0.2.
Interaction of age, NSVT, and survival.
The relative risk of sudden death in patients with NSVT varied with age, being highest in those age 30 years. Fifteen of 174 patients age 30 or younger (6 of 26 with NSVT) and 17 of 357 patients older than 30 at the time of Holter monitoring (7 of 78 with NSVT) died suddenly during follow-up. Five-year cumulative freedom for sudden death was 91.6% (95% CI: 87.3 to 95.9) in patients age 30 or younger versus 96.2% (95% CI: 93.8 to 98.6) in patients older than 30 at Holter (p = 0.2). There was no relation between NSVT and freedom for sudden death in patients older than 30 (five-year cumulative freedom 96.5% [95% CI: 94.0 to 99.0] without NSVT and 95.2% [95% CI: 89.9 to 100] with NSVT; p = 0.1). The odds ratio of sudden death in patients >30 years of age with NSVT was 2.16 (95% CI: 0.82 to 5.69; p = 0.1). In patients younger than 30, five-year freedom from sudden death was lower in the NSVT group (77.6% [95% CI: 60.2 to 95.0] with NSVT vs. 94.1% [95% CI: 90.2 to 98.0] without NSVT; p = 0.003), with an odds ratio for sudden death in patients with NSVT of 4.35 (95% CI: 1.54 to 12.28; p = 0.006) (Fig. 3).
|
|
|
|
Discussion |
|---|
|
TopAbstractMethodsResultsDiscussionReferences |
|---|
The explanation for the complex relation between age, NSVT, and sudden death risk is unclear. In older patients progressive myocyte loss and fibrosis may account for the increased incidence of NSVT in this age group. Conversely, fibrosis and myocyte loss has had less time to develop in younger patients, and, thus, ventricular arrhythmia at an early age may be rarer. However, when NSVT is present in young patients, it probably reflects a more potent arrhythmogenic substrate caused by myocyte disarray, myocardial ischemia, and abnormal autonomic function (11–13).
The implication of this study is that when NSVT occurs in isolation in young patients, it may justify prophylactic therapy to prevent SCD. In contrast, the same arrhythmia in older patients may not justify therapy when it occurs in isolation. A limitation to the study is the small sample size that could account for the lack of significant association between NSVT and sudden death in the group of more than 30 years, and studies with larger numbers of patients will be required to evaluate the prognosis value of the presence of NSVT in this age group.
Although the association between sudden death risk and NSVT in young patients is striking, it should be borne in mind that the majority of sudden deaths, even in young patients, occurred in patients without NSVT. In other words, Holter monitoring identifies only one subset of young patients at high risk, and other recognized risk factors need to be excluded in order to reassure individual patients (14). The infrequent occurrence of symptomatic or sustained ventricular tachycardia during Holter monitoring in this study means that we were unable to make any comment on their prognostic importance. However, data from other studies suggest that prolonged runs of symptomatic ventricular tachycardia are prognostically important in patients with HCM (15). When long multiple episodes of NSVT are present, further investigations to exclude coronary artery disease and to identify possible underlying mechanisms such as LV apical aneurysms are warranted (15,16).
Conclusions. Non-sustained ventricular tachycardia is associated with a substantial increase in all-cause mortality and sudden death risk in young patients with HCM. This risk is independent of the frequency, duration, and heart rate of NSVT episodes.
|
References |
|---|
|
TopAbstractMethodsResultsDiscussionReferences |
|---|
This article has been cited by other articles:
|
|
 |
|
  R. C. Saumarez, M. Pytkowski, M. Sterlinski, J. P. Bourke, J. R. Clague, S. M. Cobbe, D. T. Connelly, M. J. Griffith, P. P. McKeown, K. McLeod, et al. Paced ventricular electrogram fractionation predicts sudden cardiac death in hypertrophic cardiomyopathy Eur. Heart J., July 1, 2008; 29(13): 1653 - 1661. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Sen-Chowdhry and W. J. McKenna Non-invasive risk stratification in hypertrophic cardiomyopathy: don't throw out the baby with the bathwater Eur. Heart J., July 1, 2008; 29(13): 1600 - 1602. [Full Text] [PDF]
|
|
|
|
 |
|
 S. Basavarajaiah, A. Boraita, G. Whyte, M. Wilson, L. Carby, A. Shah, and S. Sharma Ethnic differences in left ventricular remodeling in highly-trained athletes relevance to differentiating physiologic left ventricular hypertrophy from hypertrophic cardiomyopathy. J. Am. Coll. Cardiol., June 10, 2008; 51(23): 2256 - 2262. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Nazarian and J. A.C. Lima Cardiovascular Magnetic Resonance for Risk Stratification of Arrhythmia in Hypertrophic Cardiomyopathy J. Am. Coll. Cardiol., April 8, 2008; 51(14): 1375 - 1376. [Full Text] [PDF]
|
|
|
|
|
|
S. Basavarajaiah, M. Wilson, G. Whyte, A. Shah, W. McKenna, and S. Sharma Prevalence of hypertrophic cardiomyopathy in highly trained athletes: relevance to pre-participation screening. J. Am. Coll. Cardiol., March 11, 2008; 51(10): 1033 - 1039. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Developed in Collaboration With the European Heart, D. P. Zipes, A. J. Camm, M. Borggrefe, A. E. Buxton, B. Chaitman, M. Fromer, G. Gregoratos, G. Klein, A. J. Moss, et al. ACC/AHA/ESC 2006 Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death: A Report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death) J. Am. Coll. Cardiol., September 5, 2006; 48(5): e247 - e346. [Full Text] [PDF]
|
|
|
|
 |
|
 Writing Committee Members, D. P. Zipes, A. J. Camm, M. Borggrefe, A. E. Buxton, B. Chaitman, M. Fromer, G. Gregoratos, G. Klein, A. J. Moss, et al. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: A report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death) Developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society Europace, September 1, 2006; 8(9): 746 - 837. [Full Text] [PDF]
|
|
|
|
|
|
P. M. Elliott, J. R. Gimeno, M. T. Tome, J. Shah, D. Ward, R. Thaman, J. Mogensen, and W. J. McKenna Left ventricular outflow tract obstruction and sudden death risk in patients with hypertrophic cardiomyopathy Eur. Heart J., August 2, 2006; 27(16): 1933 - 1941. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Spirito and C. Autore Management of hypertrophic cardiomyopathy. BMJ, May 27, 2006; 332(7552): 1251 - 1255. [Full Text] [PDF]
|
|
|
|
|
|
F. Enseleit and F. Duru Long-term continuous external electrocardiographic recording: a review. Europace, April 1, 2006; 8(4): 255 - 266. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. W. Nugent, P. E.F. Daubeney, P. Chondros, J. B. Carlin, S. D. Colan, M. Cheung, A. M. Davis, C.W. Chow, R. G. Weintraub, and for the National Australian Childhood Cardiomyopat Clinical Features and Outcomes of Childhood Hypertrophic Cardiomyopathy: Results From a National Population-Based Study Circulation, August 30, 2005; 112(9): 1332 - 1338. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. D. Binder, M. A. Fifer, M. E. King, and J. R. Stone Case 26-2005 - A 48-Year-Old Man with Sudden Loss of Consciousness while Jogging N. Engl. J. Med., August 25, 2005; 353(8): 824 - 832. [Full Text] [PDF]
|
|
|
|
|
|
A. S. Adabag, S. A. Casey, M. A. Kuskowski, A. G. Zenovich, and B. J. Maron Spectrum and prognostic significance of arrhythmias on ambulatory Holter electrocardiogram in hypertrophic cardiomyopathy J. Am. Coll. Cardiol., March 1, 2005; 45(5): 697 - 704. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. G Katritsis and A.J. Camm Nonsustained ventricular tachycardia: where do we stand? Eur. Heart J., July 1, 2004; 25(13): 1093 - 1099. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Nonsustained VT Predicts Sudden Death in Young HCM Patients Journal Watch Cardiology, November 28, 2003; 2003(1128): 3 - 3. [Full Text]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | SUBSCRIPTIONS | CURRENT ISSUE | PAST ISSUES | CARDIOSOURCE | SEARCH | HELP | FEEDBACK |
