human
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Spinal cord stimulation ( SCS ) has analgesic properties and may be used to treat pain in patients with therapeutically refractory angina who are unsuitable for myocardial revascularization . Some studies have also demonstrated an anti-ischemic effect . The aim of this study was to evaluate the long-term persistence of the effects of SCS on myocardial ischemia and on heart rate variability . METHODS Fifteen patients ( 9 males , 6 females , mean age 76 + /- 8 years , range 58 - 90 years ) with severe refractory angina pectoris ( Canadian class III-IV ) , on optimal pharmacological therapy , unsuitable for myocardial revascularization and treated with SCS for a mean follow-up of 39 + /- 27 months ( range 9 - 92 months ) were studied . Eleven patients had had a previous myocardial infa rct ion and 5 a coronary artery bypass graft . The mean ejection fraction was 54 + /- 7 % ( range 36 - 65 % ) . All patients underwent 48-hour ambulatory ECG monitoring and were r and omly assigned to 24 hours without SCS ( off period ) and 24 hours with SCS ( on period ) . The primary endpoints were : number of ischemic episodes , total duration of ischemic episodes ( min ) , and total ischemic burden ( mV*min ) . RESULTS The heart rate was not statistically different during the off and on SCS periods ( median 64 and 67 b/min respectively ) . The number of ischemic episodes decreased from a median of 6 ( range 0 - 29 ) during the off period to 3 ( range 0 - 24 ) during the on period ( p < 0.05 ) . The total duration of ischemic episodes decreased from a median of 29 min ( range 0- 186 min ) during the off period to 16 min ( range 0 - 123 min ) during the on period ( p < 0.05 ) . The total ischemic burden decreased from a median of 2.5 mV*min ( range 0 - 19.5 mV*min ) during the off period to 0.8 mV*min ( range 0 - 13 mV*min ) during the on period ( p = NS ) . The heart rate variability parameters were similar during the on and off periods . CONCLUSIONS SCS exerts long-term anti-ischemic effects Background Patients with refractory angina have significant morbidity . This study aim ed to compare two of the treatment options , Spinal Cord Stimulation ( SCS ) and Percutaneous Myocardial Laser Revascularisation ( PMR ) in terms of clinical outcomes and cost-effectiveness . Methods Eligible patients were r and omised to PMR or SCS  and followed up for exercise tolerance time ( ETT ) , Canadian Cardiovascular Society ( CCS ) classification and the quality of life measures SF-36 , Seattle Angina Question naire and the EuroQoL at 3 , 12 and 24 months . Utilities were calculated using the EQ-5D and these and costs were compared between groups . The incremental cost-effectiveness ratio ( ICER ) per QALY for SCS compared to PMR was also calculated . Results At 24 months post-r and omisation , patients that had SCS and PMR had similar ETT ( mean difference 0.05 , 95 % CI -2.08 , 2.18 , p = 0.96 ) and there was no difference in CCS classification or quality of life outcomes . The difference in overall mean costs when comparing SCS to PMR was GBP5,520 ( 95 % CI GBP1,966 to GBP8,613 ; p < 0.01 ) and the ICER of using SCS was GBP46,000 per QALY . Conclusion Outcomes after SCS did not differ appreciably from those after PMR , with the former procedure being less cost-effective as currently applied . Larger studies could clarify which patients would most benefit from SCS , potentially increasing cost-effectiveness . Trial registration Current Controlled Trials IS RCT The present study is a 2-year follow-up of the 104 patients participating in the ESBY study ( Electrical Stimulation versus Coronary Artery Bypass Surgery in Severe Angina Pectoris ) , a r and omised prospect i ve study including patients with increased surgical risk and no prognostic benefit from revascularisation .  Hospital care costs , morbidity and causes of death after spinal cord stimulation ( SCS ) and coronary artery bypass grafting ( CABG ) were assessed , as well as the complication rate of SCS treatment . SCS proved to be a less expensive symptomatic treatment modality of angina pectoris than CABG ( p < 0.01 ) . The SCS group had fewer hospitalisation days related to the primary intervention ( p < 0.0001 ) and fewer hospitalisation days due to cardiac events ( p < 0.05 ) . The groups did not differ with regard to causes of death . There were no serious complications related to the SCS treatment BACKGROUND Spinal cord stimulation ( SCS ) has been shown to have antianginal and anti-ischemic effects in severe angina pectoris . The present study was performed to investigate whether SCS can be used as an alternative to coronary artery bypass grafting ( CABG ) in selected patient groups , ie , patients with no proven prognostic benefit from CABG and with an increased surgical risk . METHODS AND RESULTS One hundred four patients were r and omized ( SCS , 53 ; CABG , 51 ) . The patients were assessed with respect to symptoms , exercise capacity , ischemic ECG changes during exercise , rate-pressure product , mortality , and cardiovascular morbidity before and 6 months after the operation . Both groups had adequate symptom relief ( P<.0001 ) , and there was no difference between SCS and CABG . The CABG group had an increase in exercise capacity ( P=.02 ) , less ST-segment depression on maximum ( P=.005 ) and comparable ( P=.0009 ) workloads , and an increase in the rate-pressure product both at maximum ( P=.0003 ) and comparable ( P=.03 ) workloads compared with the SCS group . Eight deaths occurred during the follow-up period , 7 in the CABG group and 1 in the SCS group . On an intention-to-treat basis , the mortality rate was lower in the SCS group ( P=.02 ) . Cerebrovascular morbidity was also lower in the SCS group ( P=.03 ) . CONCLUSIONS CABG and SCS appear to be equivalent methods in terms of symptom relief in this group of patients . Effects on ischemia , morbidity , and mortality should be considered in the choice of treatment method . Taking all factors into account , it seems reasonable to conclude that SCS may be a therapeutic alternative for patients with an increased risk of surgical complications Background : Spinal cord stimulation ( SCS ) is an alternative treatment option for refractory angina . Controlled trials demonstrate symptom relief and improvement in functional status . Since patients experience retrosternal prickling during active SCS , there is no option for blinding patients to active treatment or for placebo control . Objective : To examine the therapeutic effects of subthreshold SCS in patients with refractory angina in a placebo-controlled study . Methods : 12 responders to treatment who had already been treated with SCS for refractory angina were enrolled . Patients were r and omised into four consecutive treatment arms , each for 4 weeks , with various stimulation timing and output parameters : 3 × 2 h/day ( phase A ) and 24 h/day with conventional output ( phase B ) ; 3 × 2 h/day with a subthreshold output ( phase C ) ; and 24 h/day with 0.1 V output , which served as control ( phase D ) . Functional status , quality of life , Canadian Cardiovascular Society classification and nitrate usage were assessed at the end of each 4-week period . Results : In phase D , patients showed a significant reduction in walking distance compared with phases A and C. Canadian Cardiovascular Society classification worsened in phase D compared with phases A – C. Frequency of angina attacks and the visual analogue scale were significantly worse in phase D than in phases A – C. In three patients , it was necessary to prematurely terminate phase D owing to intolerable angina attacks . Conclusions : In this first placebo-controlled trial to apply SCS in patients with refractory angina , improvement in functional status and symptoms was revealed in phases with conventional or subthreshold stimulation , in comparison to a low-output ( placebo ) phase The present study assessed the reoccurrence of myocardial ischemia after withholding electrical neurostimulation .  After r and omization , in the study or withdrawal group , spinal cord stimulation ( SCS ) was set active during the first 4 weeks , followed by 4 weeks of withholding stimulation . In the control group , SCS was switched off during 4 weeks before the end of the study . The control group had no crossover period . Measurements were done at baseline , then after 4 and 8 weeks . The first periods at 4 weeks of each sequence of both groups were compared . In addition , a comparison of clinical variables was performed between the study group 4 weeks after withholding stimulation and the control group 4 weeks following r and omization . A total number of 24 patients with refractory angina and an implanted spinal cord stimulator were included in the study ( n = 12 ) and control group .  Angina pectoris complaints , nitroglycerin intake , ischemia , and heart rate variability using 48-hour ambulatory electrocardiographic monitoring were assessed . In addition , neurohormonal status and symptom-limited aerobic capacity were evaluated . There was no increase of anginal complaints or ischemia after withholding stimulation . Neurohormonal levels and aerobic capacity were not altered . We conclude that there is no adverse clinical rebound phenomenon after withholding neurostimulation in patients with refractory angina pectoris & NA ; Spinal cord stimulation ( SCS ) is believed to be effective in treating  refractory angina . The need for SCS‐related chest paresthesia , however , has hitherto made impossible placebo‐controlled trials . Subliminal ( non paresthesic ) SCS , however , might be also effective on anginal pain . In this trial we compared subliminal SCS with paresthesic SCS and with sham SCS .  Twenty‐five refractory angina patients , who had never received SCS before , underwent SCS device implantation and were r and omized to three groups : paresthesic SCS ( group PS ; n = 10 ) , subliminal SCS ( group SS ; n = 7 ) or “ sham ” SCS ( group NS ; n = 8) . After 1 month group NS patients were r and omized to either group PS or SS . After 1 month , changes in angina episodes ( p = 0.016 ) , nitroglycerin use ( p = 0.015 ) , angina class ( p = 0.02 ) , quality of life score ( p = 0.05 ) , and items 2 ( p = 0.008 ) and 3 ( p = 0.009 ) of Seattle angina question naire differed significantly among groups . Group PS showed significant improvement in outcomes compared to group NS , whereas there were no significant differences between groups SS and NS ; furthermore , only nitroglycerin use differed significantly between groups PS and SS . At 3 months , a significant difference between groups PS and SS was observed in angina attacks ( p = 0.002 ) , but not in other variables . Thus , in this study , paresthesic , but not subliminal SCS was superior to sham SCS in improving clinical status in refractory angina patients . The lack of significant differences between PS and SS groups in this small study suggests that a possible role for subliminal SCS in individual patients deserves to be assessed in larger trials with appropriate statistical power AIMS To assess the long-term outcome regarding quality of life and survival in patients who were included in the ESBY study 1992 - 1995 . The ESBY study ( Electrical Stimulation versus Coronary Artery Bypass Surgery in Severe Angina Pectoris ) included 104 patients -with severe angina , increased surgical risk and no prognostic benefits from revascularization-r and omized to coronary artery bypass grafting or spinal cord stimulation .  METHODS AND RESULTS The ESBY patients '  quality of life was analysed using two question naires , and 5-year mortality was assessed . Quality of life improved significantly 6 months after spinal cord stimulation and coronary artery bypass grafting , respectively , compared to run-in ( P<0.001 ) . The results were consistent after 4.8 years . The 5-year mortality was 27.9 % . There were no significant differences between the groups . CONCLUSIONS Spinal cord stimulation as well as coronary artery bypass grafting offered long-lasting improvement in quality of life . Survival up to 5 years was comparable between the groups . Both methods can be considered as effective treatment options for patients with severe angina , increased surgical risks and estimated to have no prognostic benefits from coronary artery bypass grafting OBJECTIVES In a prospect i ve , r and omized study with an 8-week follow-up period , we evaluated the efficacy of spinal cord stimulation on exercise capacity and quality of life in patients with intractable angina . BACKGROUND Despite important achievements in therapy for ischemic heart disease , there remain patients with intractable symptoms of angina . In uncontrolled observations , several investigators have reported beneficial effects of spinal cord stimulation as an additional therapy for patients with angina pectoris . METHODS Seventeen patients were r and omly assigned to the treatment ( implantation within 2 weeks , eight patients ) or control ( implantation after 8 weeks , nine patients ) group . Assessment of exercise capacity was performed by treadmill exercise testing .  Quality of life was evaluated by daily and social activity scores and recording sublingual glyceryl trinitrate 
    Output:
    
agent
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Spinal cord stimulation ( SCS ) has analgesic properties and may be used to treat pain in patients with therapeutically refractory angina who are unsuitable for myocardial revascularization . Some studies have also demonstrated an anti-ischemic effect . The aim of this study was to evaluate the long-term persistence of the effects of SCS on myocardial ischemia and on heart rate variability . METHODS Fifteen patients ( 9 males , 6 females , mean age 76 + /- 8 years , range 58 - 90 years ) with severe refractory angina pectoris ( Canadian class III-IV ) , on optimal pharmacological therapy , unsuitable for myocardial revascularization and treated with SCS for a mean follow-up of 39 + /- 27 months ( range 9 - 92 months ) were studied . Eleven patients had had a previous myocardial infa rct ion and 5 a coronary artery bypass graft . The mean ejection fraction was 54 + /- 7 % ( range 36 - 65 % ) . All patients underwent 48-hour ambulatory ECG monitoring and were r and omly assigned to 24 hours without SCS ( off period ) and 24 hours with SCS ( on period ) . The primary endpoints were : number of ischemic episodes , total duration of ischemic episodes ( min ) , and total ischemic burden ( mV*min ) . RESULTS The heart rate was not statistically different during the off and on SCS periods ( median 64 and 67 b/min respectively ) . The number of ischemic episodes decreased from a median of 6 ( range 0 - 29 ) during the off period to 3 ( range 0 - 24 ) during the on period ( p < 0.05 ) . The total duration of ischemic episodes decreased from a median of 29 min ( range 0- 186 min ) during the off period to 16 min ( range 0 - 123 min ) during the on period ( p < 0.05 ) . The total ischemic burden decreased from a median of 2.5 mV*min ( range 0 - 19.5 mV*min ) during the off period to 0.8 mV*min ( range 0 - 13 mV*min ) during the on period ( p = NS ) . The heart rate variability parameters were similar during the on and off periods . CONCLUSIONS SCS exerts long-term anti-ischemic effects Background Patients with refractory angina have significant morbidity . This study aim ed to compare two of the treatment options , Spinal Cord Stimulation ( SCS ) and Percutaneous Myocardial Laser Revascularisation ( PMR ) in terms of clinical outcomes and cost-effectiveness . Methods Eligible patients were r and omised to PMR or SCS  and followed up for exercise tolerance time ( ETT ) , Canadian Cardiovascular Society ( CCS ) classification and the quality of life measures SF-36 , Seattle Angina Question naire and the EuroQoL at 3 , 12 and 24 months . Utilities were calculated using the EQ-5D and these and costs were compared between groups . The incremental cost-effectiveness ratio ( ICER ) per QALY for SCS compared to PMR was also calculated . Results At 24 months post-r and omisation , patients that had SCS and PMR had similar ETT ( mean difference 0.05 , 95 % CI -2.08 , 2.18 , p = 0.96 ) and there was no difference in CCS classification or quality of life outcomes . The difference in overall mean costs when comparing SCS to PMR was GBP5,520 ( 95 % CI GBP1,966 to GBP8,613 ; p < 0.01 ) and the ICER of using SCS was GBP46,000 per QALY . Conclusion Outcomes after SCS did not differ appreciably from those after PMR , with the former procedure being less cost-effective as currently applied . Larger studies could clarify which patients would most benefit from SCS , potentially increasing cost-effectiveness . Trial registration Current Controlled Trials IS RCT The present study is a 2-year follow-up of the 104 patients participating in the ESBY study ( Electrical Stimulation versus Coronary Artery Bypass Surgery in Severe Angina Pectoris ) , a r and omised prospect i ve study including patients with increased surgical risk and no prognostic benefit from revascularisation .  Hospital care costs , morbidity and causes of death after spinal cord stimulation ( SCS ) and coronary artery bypass grafting ( CABG ) were assessed , as well as the complication rate of SCS treatment . SCS proved to be a less expensive symptomatic treatment modality of angina pectoris than CABG ( p < 0.01 ) . The SCS group had fewer hospitalisation days related to the primary intervention ( p < 0.0001 ) and fewer hospitalisation days due to cardiac events ( p < 0.05 ) . The groups did not differ with regard to causes of death . There were no serious complications related to the SCS treatment BACKGROUND Spinal cord stimulation ( SCS ) has been shown to have antianginal and anti-ischemic effects in severe angina pectoris . The present study was performed to investigate whether SCS can be used as an alternative to coronary artery bypass grafting ( CABG ) in selected patient groups , ie , patients with no proven prognostic benefit from CABG and with an increased surgical risk . METHODS AND RESULTS One hundred four patients were r and omized ( SCS , 53 ; CABG , 51 ) . The patients were assessed with respect to symptoms , exercise capacity , ischemic ECG changes during exercise , rate-pressure product , mortality , and cardiovascular morbidity before and 6 months after the operation . Both groups had adequate symptom relief ( P<.0001 ) , and there was no difference between SCS and CABG . The CABG group had an increase in exercise capacity ( P=.02 ) , less ST-segment depression on maximum ( P=.005 ) and comparable ( P=.0009 ) workloads , and an increase in the rate-pressure product both at maximum ( P=.0003 ) and comparable ( P=.03 ) workloads compared with the SCS group . Eight deaths occurred during the follow-up period , 7 in the CABG group and 1 in the SCS group . On an intention-to-treat basis , the mortality rate was lower in the SCS group ( P=.02 ) . Cerebrovascular morbidity was also lower in the SCS group ( P=.03 ) . CONCLUSIONS CABG and SCS appear to be equivalent methods in terms of symptom relief in this group of patients . Effects on ischemia , morbidity , and mortality should be considered in the choice of treatment method . Taking all factors into account , it seems reasonable to conclude that SCS may be a therapeutic alternative for patients with an increased risk of surgical complications Background : Spinal cord stimulation ( SCS ) is an alternative treatment option for refractory angina . Controlled trials demonstrate symptom relief and improvement in functional status . Since patients experience retrosternal prickling during active SCS , there is no option for blinding patients to active treatment or for placebo control . Objective : To examine the therapeutic effects of subthreshold SCS in patients with refractory angina in a placebo-controlled study . Methods : 12 responders to treatment who had already been treated with SCS for refractory angina were enrolled . Patients were r and omised into four consecutive treatment arms , each for 4 weeks , with various stimulation timing and output parameters : 3 × 2 h/day ( phase A ) and 24 h/day with conventional output ( phase B ) ; 3 × 2 h/day with a subthreshold output ( phase C ) ; and 24 h/day with 0.1 V output , which served as control ( phase D ) . Functional status , quality of life , Canadian Cardiovascular Society classification and nitrate usage were assessed at the end of each 4-week period . Results : In phase D , patients showed a significant reduction in walking distance compared with phases A and C. Canadian Cardiovascular Society classification worsened in phase D compared with phases A – C. Frequency of angina attacks and the visual analogue scale were significantly worse in phase D than in phases A – C. In three patients , it was necessary to prematurely terminate phase D owing to intolerable angina attacks . Conclusions : In this first placebo-controlled trial to apply SCS in patients with refractory angina , improvement in functional status and symptoms was revealed in phases with conventional or subthreshold stimulation , in comparison to a low-output ( placebo ) phase The present study assessed the reoccurrence of myocardial ischemia after withholding electrical neurostimulation .  After r and omization , in the study or withdrawal group , spinal cord stimulation ( SCS ) was set active during the first 4 weeks , followed by 4 weeks of withholding stimulation . In the control group , SCS was switched off during 4 weeks before the end of the study . The control group had no crossover period . Measurements were done at baseline , then after 4 and 8 weeks . The first periods at 4 weeks of each sequence of both groups were compared . In addition , a comparison of clinical variables was performed between the study group 4 weeks after withholding stimulation and the control group 4 weeks following r and omization . A total number of 24 patients with refractory angina and an implanted spinal cord stimulator were included in the study ( n = 12 ) and control group .  Angina pectoris complaints , nitroglycerin intake , ischemia , and heart rate variability using 48-hour ambulatory electrocardiographic monitoring were assessed . In addition , neurohormonal status and symptom-limited aerobic capacity were evaluated . There was no increase of anginal complaints or ischemia after withholding stimulation . Neurohormonal levels and aerobic capacity were not altered . We conclude that there is no adverse clinical rebound phenomenon after withholding neurostimulation in patients with refractory angina pectoris & NA ; Spinal cord stimulation ( SCS ) is believed to be effective in treating  refractory angina . The need for SCS‐related chest paresthesia , however , has hitherto made impossible placebo‐controlled trials . Subliminal ( non paresthesic ) SCS , however , might be also effective on anginal pain . In this trial we compared subliminal SCS with paresthesic SCS and with sham SCS .  Twenty‐five refractory angina patients , who had never received SCS before , underwent SCS device implantation and were r and omized to three groups : paresthesic SCS ( group PS ; n = 10 ) , subliminal SCS ( group SS ; n = 7 ) or “ sham ” SCS ( group NS ; n = 8) . After 1 month group NS patients were r and omized to either group PS or SS . After 1 month , changes in angina episodes ( p = 0.016 ) , nitroglycerin use ( p = 0.015 ) , angina class ( p = 0.02 ) , quality of life score ( p = 0.05 ) , and items 2 ( p = 0.008 ) and 3 ( p = 0.009 ) of Seattle angina question naire differed significantly among groups . Group PS showed significant improvement in outcomes compared to group NS , whereas there were no significant differences between groups SS and NS ; furthermore , only nitroglycerin use differed significantly between groups PS and SS . At 3 months , a significant difference between groups PS and SS was observed in angina attacks ( p = 0.002 ) , but not in other variables . Thus , in this study , paresthesic , but not subliminal SCS was superior to sham SCS in improving clinical status in refractory angina patients . The lack of significant differences between PS and SS groups in this small study suggests that a possible role for subliminal SCS in individual patients deserves to be assessed in larger trials with appropriate statistical power AIMS To assess the long-term outcome regarding quality of life and survival in patients who were included in the ESBY study 1992 - 1995 . The ESBY study ( Electrical Stimulation versus Coronary Artery Bypass Surgery in Severe Angina Pectoris ) included 104 patients -with severe angina , increased surgical risk and no prognostic benefits from revascularization-r and omized to coronary artery bypass grafting or spinal cord stimulation .  METHODS AND RESULTS The ESBY patients '  quality of life was analysed using two question naires , and 5-year mortality was assessed . Quality of life improved significantly 6 months after spinal cord stimulation and coronary artery bypass grafting , respectively , compared to run-in ( P<0.001 ) . The results were consistent after 4.8 years . The 5-year mortality was 27.9 % . There were no significant differences between the groups . CONCLUSIONS Spinal cord stimulation as well as coronary artery bypass grafting offered long-lasting improvement in quality of life . Survival up to 5 years was comparable between the groups . Both methods can be considered as effective treatment options for patients with severe angina , increased surgical risks and estimated to have no prognostic benefits from coronary artery bypass grafting OBJECTIVES In a prospect i ve , r and omized study with an 8-week follow-up period , we evaluated the efficacy of spinal cord stimulation on exercise capacity and quality of life in patients with intractable angina . BACKGROUND Despite important achievements in therapy for ischemic heart disease , there remain patients with intractable symptoms of angina . In uncontrolled observations , several investigators have reported beneficial effects of spinal cord stimulation as an additional therapy for patients with angina pectoris . METHODS Seventeen patients were r and omly assigned to the treatment ( implantation within 2 weeks , eight patients ) or control ( implantation after 8 weeks , nine patients ) group . Assessment of exercise capacity was performed by treadmill exercise testing .  Quality of life was evaluated by daily and social activity scores and recording sublingual glyceryl trinitrate 
    Output:
    