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EP News: Clinical
EP News: Clinical N.A. Mark Estes III, MD, FHRS From the Tufts Medical Center, Boston, Massachusetts.
Mobile-phone dispatch of laypersons for CPR in out-of-hospital cardiac arrest Ringh et al (New Engl J Med 2015;372:2316, PMID 26061836) conducted a blinded randomized controlled trial to evaluate rates of bystander-initiated cardiopulmonary resuscitation (CPR) with the use of a mobile-phone positioning system. This system could instantly locate mobile-phone users and dispatch lay volunteers trained in CPR to the nearby patient with out-of-hospital cardiac arrest. The primary outcome was bystander-initiated CPR before the arrival of emergency medical services. Overall, 9828 lay volunteers were recruited and trained. The positioning system was activated in 667 cardiac arrests: 306 patients (46%) in the intervention group and 361 patients (54%) in the control group. The rate of bystander-initiated CPR was 62% (188 of 305) in the intervention group and 48% (172 of 360) in the control group (P o .001). The authors conclude that this system used to dispatch lay volunteers was associated with significantly increased rates of bystander-initiated CPR for out-of-hospital cardiac arrest.
Cardiac electrophysiological substrate underlying the ECG phenotype and electrogram abnormalities in Brugada Syndrome patients Zhang et al (Circulation 2015;131:1950, PMID 25810336) evaluated the electrophysiological substrate of 25 patients with Brugada syndrome (BrS) using noninvasive electrocardiogram (ECG) imaging. Seven healthy subjects provided control data, and 6 patients with right bundle branch block were studied for comparison. Abnormal substrate was observed exclusively in the right ventricular outflow tract in BrS with the following properties: (1) ST-segment elevation and inverted T wave of unipolar electrograms (2.21 ⫾ 0.67 mV vs 0 mV); (2) delayed right ventricular outflow tract activation (82 ⫾ 18 ms vs 37 ⫾ 11 ms); (3) low-amplitude (0.47 ⫾ 0.16 mV vs 3.74 ⫾ 1.60 mV) and fractionated electrograms, suggesting slow discontinuous conduction; (4) prolonged recovery time (381 ⫾ 30 ms vs 311 ⫾ 34 ms) and activation recovery intervals (318 ⫾ 32 ms vs 241 ⫾ 27 ms), indicating delayed repolarization; (5) steep repolarization gradients at right ventricular outflow tract borders (P o .005 in comparison with healthy controls for all). Unlike BrS, right bundle branch block had delayed activation in the entire right ventricle, without ST-segment elevation, fractionation, or repolarization abnormalities on electrograms. The authors conclude that both slow discontinuous conduction and steep dispersion of repolarization are present in the right ventricular outflow tract of patients with BrS and that ECG Address reprint requests and correspondence: Dr N.A. Mark Estes III, Tufts Medical Center, 800 Washington St, Boston, MA 02111. E-mail address: [email protected].
1547-5271/$-see front matter
imaging can differentiate between BrS and right bundle branch block.
Catecholaminergic polymorphic ventricular tachycardia: The role of left cardiac sympathetic denervation De Ferrari et al (Circulation 2015;131:2185, PMID 2601915) evaluated 63 patients with catecholaminergic polymorphic ventricular tachycardia (CPVT) who underwent left cardiac sympathetic denervation (LCSD) as secondary (n ¼ 54) or primary (n ¼ 9) prevention. The 9 asymptomatic patients remained free of major cardiac events at a mean follow-up of 37 months. Of the 54 patients with previous major cardiac events either on (n ¼ 38) or off (n ¼ 16) optimal medical therapy, 13 (24%) had at least 1 recurrence. The 2-year cumulative event-free survival rate was 81%. The percentage of patients with major cardiac events despite optimal medical therapy (n ¼ 38) was reduced from 100% to 32% (P o .001) after LCSD. In 29 patients with a presurgical implantable cardioverter-defibrillator (ICD), the rate of shocks decreased by 93% from 3.6 to 0.6 shocks per person-year (P o .001). The authors conclude that LCSD is an effective antifibrillatory intervention for patients with CPVT and that whenever syncope occurs despite optimal medical therapy, LCSD should be considered the next step rather than an ICD and could complement ICDs in patients with recurrent shocks.
Implantable cardioverter-defibrillator use among patients with low ejection fraction after acute myocardial infarction Pokorney et al (JAMA 2015;313:2433, PMID 26103027) examined implantable cardioverter-defibrillator (ICD) implantation rates and associated mortality among older myocardial infarction (MI) patients with low ejection fraction (EF) in a retrospective observational study of patients with an EF of r35% after MI who were treated at 441 US hospitals between 2007 and 2010. In 10,318 MI patients with EF of r35%, the cumulative 1-year ICD implantation rate was 8.1%. Patients with ICD were more likely to have previous coronary artery bypass graft procedures, higher peak troponin levels, in-hospital cardiogenic shock, and cardiology follow-up within 2 weeks of discharge as compared with patients who did not receive an ICD within 1 year. Implantation of ICD was associated with lower 2-year mortality (15.3 events per 100 patient-years [128 deaths in 838 patient-years] vs 26.4 events per 100 patient-years [3033 deaths in 11,479 patient-years]; adjusted hazard ratio 0.64; 95% confidence interval 0.53–0.78). The authors conclude that fewer than 1 in 10 eligible patients with low EF received an ICD within 1 year after MI and that ICD implantation was associated with lower risk-adjusted mortality at 2 years.
http://dx.doi.org/10.1016/j.hrthm.2015.07.005
Mobile-phone dispatch of laypersons for CPR in out-of-hospital cardiac arrest Ringh et al (New Engl J Med 2015;372:2316, PMID 26061836) conducted a blinded randomized controlled trial to evaluate rates of bystander-initiated cardiopulmonary resuscitation (CPR) with the use of a mobile-phone positioning system. This system could instantly locate mobile-phone users and dispatch lay volunteers trained in CPR to the nearby patient with out-of-hospital cardiac arrest. The primary outcome was bystander-initiated CPR before the arrival of emergency medical services. Overall, 9828 lay volunteers were recruited and trained. The positioning system was activated in 667 cardiac arrests: 306 patients (46%) in the intervention group and 361 patients (54%) in the control group. The rate of bystander-initiated CPR was 62% (188 of 305) in the intervention group and 48% (172 of 360) in the control group (P o .001). The authors conclude that this system used to dispatch lay volunteers was associated with significantly increased rates of bystander-initiated CPR for out-of-hospital cardiac arrest.
Cardiac electrophysiological substrate underlying the ECG phenotype and electrogram abnormalities in Brugada Syndrome patients Zhang et al (Circulation 2015;131:1950, PMID 25810336) evaluated the electrophysiological substrate of 25 patients with Brugada syndrome (BrS) using noninvasive electrocardiogram (ECG) imaging. Seven healthy subjects provided control data, and 6 patients with right bundle branch block were studied for comparison. Abnormal substrate was observed exclusively in the right ventricular outflow tract in BrS with the following properties: (1) ST-segment elevation and inverted T wave of unipolar electrograms (2.21 ⫾ 0.67 mV vs 0 mV); (2) delayed right ventricular outflow tract activation (82 ⫾ 18 ms vs 37 ⫾ 11 ms); (3) low-amplitude (0.47 ⫾ 0.16 mV vs 3.74 ⫾ 1.60 mV) and fractionated electrograms, suggesting slow discontinuous conduction; (4) prolonged recovery time (381 ⫾ 30 ms vs 311 ⫾ 34 ms) and activation recovery intervals (318 ⫾ 32 ms vs 241 ⫾ 27 ms), indicating delayed repolarization; (5) steep repolarization gradients at right ventricular outflow tract borders (P o .005 in comparison with healthy controls for all). Unlike BrS, right bundle branch block had delayed activation in the entire right ventricle, without ST-segment elevation, fractionation, or repolarization abnormalities on electrograms. The authors conclude that both slow discontinuous conduction and steep dispersion of repolarization are present in the right ventricular outflow tract of patients with BrS and that ECG Address reprint requests and correspondence: Dr N.A. Mark Estes III, Tufts Medical Center, 800 Washington St, Boston, MA 02111. E-mail address: [email protected].
1547-5271/$-see front matter
imaging can differentiate between BrS and right bundle branch block.
Catecholaminergic polymorphic ventricular tachycardia: The role of left cardiac sympathetic denervation De Ferrari et al (Circulation 2015;131:2185, PMID 2601915) evaluated 63 patients with catecholaminergic polymorphic ventricular tachycardia (CPVT) who underwent left cardiac sympathetic denervation (LCSD) as secondary (n ¼ 54) or primary (n ¼ 9) prevention. The 9 asymptomatic patients remained free of major cardiac events at a mean follow-up of 37 months. Of the 54 patients with previous major cardiac events either on (n ¼ 38) or off (n ¼ 16) optimal medical therapy, 13 (24%) had at least 1 recurrence. The 2-year cumulative event-free survival rate was 81%. The percentage of patients with major cardiac events despite optimal medical therapy (n ¼ 38) was reduced from 100% to 32% (P o .001) after LCSD. In 29 patients with a presurgical implantable cardioverter-defibrillator (ICD), the rate of shocks decreased by 93% from 3.6 to 0.6 shocks per person-year (P o .001). The authors conclude that LCSD is an effective antifibrillatory intervention for patients with CPVT and that whenever syncope occurs despite optimal medical therapy, LCSD should be considered the next step rather than an ICD and could complement ICDs in patients with recurrent shocks.
Implantable cardioverter-defibrillator use among patients with low ejection fraction after acute myocardial infarction Pokorney et al (JAMA 2015;313:2433, PMID 26103027) examined implantable cardioverter-defibrillator (ICD) implantation rates and associated mortality among older myocardial infarction (MI) patients with low ejection fraction (EF) in a retrospective observational study of patients with an EF of r35% after MI who were treated at 441 US hospitals between 2007 and 2010. In 10,318 MI patients with EF of r35%, the cumulative 1-year ICD implantation rate was 8.1%. Patients with ICD were more likely to have previous coronary artery bypass graft procedures, higher peak troponin levels, in-hospital cardiogenic shock, and cardiology follow-up within 2 weeks of discharge as compared with patients who did not receive an ICD within 1 year. Implantation of ICD was associated with lower 2-year mortality (15.3 events per 100 patient-years [128 deaths in 838 patient-years] vs 26.4 events per 100 patient-years [3033 deaths in 11,479 patient-years]; adjusted hazard ratio 0.64; 95% confidence interval 0.53–0.78). The authors conclude that fewer than 1 in 10 eligible patients with low EF received an ICD within 1 year after MI and that ICD implantation was associated with lower risk-adjusted mortality at 2 years.
http://dx.doi.org/10.1016/j.hrthm.2015.07.005