Feasibility of physiological pacing rate in cardiac resynchronization therapy.

AIMS: Although cardiac resynchronization therapy (CRT) improves functional capacity in heart failure patients, a blunted heart rate (HR) response remains after treatment. So we aimed to evaluate the feasibility of the physiological pacing rate (PPR) in CRT patients. METHODS: A cohort of 30 clinical mildly symptomatic CRT patients underwent the six-minute walk test (6MWT). During the 6MWT, HR, blood pressure, and maximum walking distance were assessed. The measurements were obtained in a pre to post manner, with CRT at nominal settings and with the physiological phase (CRT PPR), in which HR was increased by 10% above the maximum HR achieved previously. The CRT cohort also comprised a matched control group (CRT CG). In the CRT CG, the 6MWT was repeated after the standard evaluation with no PPR. The evaluations were blinded for patients and for the 6MWT evaluator. RESULTS: During the 6MWT, CRT PPR led to an increase in walking distance of 40.5 m (9.2%; P < 0.0001) when compared with baseline trial. Additionally, CRT PPR increased the maximum walking distance compared with CRT CG 479.3 ± 68.9 m vs. 420.3 ± 44.8 m, respectively, P = 0.001. In the CRT CG, CRT PPR increased the variation in walking distance, compared with baseline trials, respectively 2.40 ± 3.8% vs. 9.25 ± 7.0%, P = 0.007. CONCLUSIONS: In mildly symptomatic CRT patients PPR is feasible, leading to improvements in functional capacity. In this regard, the efficacy of PPR must be confirmed by controlled randomized trials.

Myocardial function reclassification: Echocardiographic strain patterns in patients with chronic Chagas cardiomyopathy and intraventricular dyssynchrony.

BACKGROUND: We aimed to identify, among Chronic Chagas Cardiomyopathy (CCC) patients with left ventricular dysfunction (LVD) and non-left bundle branch block (non-LBBB), subgroups with different functional and mechanical patterns of global longitudinal strain (GLS) and intraventricular dyssynchrony (IVD) at rest and after exercise stress test, and reclassify them using a new echocardiographic approach. METHODOLOGY: In this single-center cross-sectional study, 40 patients with CCC, left ventricular ejection fraction (LVEF) ≤ 35% and non-LBBB underwent rest echocardiography and then treadmill exercise stress echocardiography with GLS and IVD analysis. The sample was divided into four groups, based on GLS and IVD significant variation between rest and exercise: GLS + IVD+ (9 patients); GLS + IVD- (9 patients); GLS-IVD+ (10 patients); GLS-IVD- (10 patients). RESULTS: At rest, median LVEF was 28% (21.3%-33%) and GLS (-7% (-5%/-9.3%), were not different among groups. The average response of GLS was an increase of 0.74% over rest values, and the average response of IVD was a decrease of 6.9 ms. Group GLS-IVD+ presented more dyssynchrony at rest (p = 0.01). Left atrial (LA) volume (higher in GLS-IVD-) (p = 0.022) and TAPSE (higher in GLS + IVD+) (p = 0.015) were also different among groups at baseline. Of the 40 patients evaluated, 27 (67.5%) had very severe LVD (GLS < -8%). In addition, among these patients, 11 patients had contractile reserve after undergoing stress echocardiography. CONCLUSIONS: In patients with CCC, severe LVD and non-LBBB, the evaluation of GLS and IVD between rest and exercise was able to reclassify myocardial function and to identify subgroups with contractile reserve and significant dyssynchronopathy.

Cardiac resynchronization therapy restores muscular metaboreflex control.

INTRODUCTION: The muscular metaboreflex, whose activation regulates blood flow during isometric and aerobic exercise, is blunted in patients with heart failure (HF), and cardiac resynchronization therapy (CRT) may restore this regulatory reflex. OBJECTIVE: To evaluate metaboreflex responses after CRT. METHODS: Thirteen HF patients and 12 age-matched healthy control subjects underwent the following evaluations (pre- and post-CRT implantation in the patient group): (a) heart rate, blood pressure, and forearm blood flow measurements; (b) muscle sympathetic nerve activity (MSNA) evaluation; and (c) peak oxygen consumption (VO2peak ). Examinations were performed at rest, during moderate isometric exercise (IE), and during forearm ischemia (metaboreflex activation). The primary outcome was the increment in MSNA during limb ischemia compared to the rest moment (ΔMSNA rest to metaboreflex activation). RESULTS: After CRT, rest MSNA decreased in the HF participants: 50.4 ± 9.2 bursts/min pre-CRT vs 34.0 ± 14.4 bursts/min post-CRT, P = .001, accompanied by an improvement in systolic blood pressure and in rate-pressure product. MSNA during limb ischemia decreased: 56.6 ± 11.5 bursts/min pre-CRT vs 43.6 ± 12.7 bursts/min post-CRT, P = .001, and the ΔMSNA rest to metaboreflex activation increased: 0% (interquartile range [IQR)], -7 to 9) vs 13% (IQR, 5-30), P = .03. An augmentation of mean blood pressure during limb ischemia post-CRT was noticed: 94 mmHg (IQR, 81-104) vs 110 mmHg (IQR, 100-117), P = .04. CRT improved VO2peak , and this improvement was correlated with diminution in ΔMSNA pre- to post-CRT at rest moment (rs = -0.74, P = .006). CONCLUSION: CRT provides metaboreflex sensitization and MSNA enhancement. The restoration of sympathetic responsiveness correlates with the improvement in functional capacity.

Effect of chronic kidney disease in ischemic cardiomyopathy: Long-term follow-up - REVISION-DM2 trial.

A strong association exists between chronic kidney disease (CKD) and coronary artery disease (CAD). The role of CKD in the long-term prognosis of CAD patients with versus those without CKD is unknown. This study investigated whether CKD affects ventricular function.From January 2009 to January 2010, 918 consecutive patients were selected from an outpatient database. Patients had undergone percutaneous, surgical, or clinical treatment and were followed until May 2015.In patients with preserved renal function (n = 405), 73 events (18%) occurred, but 108 events (21.1%) occurred among those with CKD (n = 513) (P < .001). Regarding left ventricular ejection fraction (LVEF) <50%, we found 84 events (21.5%) in CKD patients and 12 (11.8%) in those with preserved renal function (P < .001). The presence of LVEF <50% brought about a modification effect. Death occurred in 22 (5.4%) patients with preserved renal function and in 73 (14.2%) with CKD (P < .001). In subjects with LVEF <50%, 66 deaths (16.9%) occurred in CKD patients and 7 (6.9%) in those with preserved renal function (P = .001). No differences were found in CKD strata regarding events or overall death among those with preserved LVEF. In a multivariate model, creatinine clearance remained an independent predictor of death (P < .001).We found no deleterious effects of CKD in patients with CAD when ventricular function was preserved. However, there was a worse prognosis in patients with CKD and ventricular dysfunction.Resgistry number is ISRCTN17786790 at https://doi.org/10.1186/ISRCTN17786790.

Impact of diabetes mellitus on ischemic cardiomyopathy. Five-year follow-up. REVISION-DM trial.

BACKGROUND: Patients with ischemic cardiomyopathy and severe left ventricular dysfunction have a worse survival prognosis than patients with preserved ventricular function. The role of diabetes in the long-term prognosis of this patient group is unknown. This study investigated whether the presence of diabetes has a long-term impact on left ventricular function. METHODS: Patients with coronary artery disease who underwent coronary artery bypass graft surgery, percutaneous coronary intervention, or medical therapy alone were included. All patients had multivessel disease and left ventricular ejection fraction measurements. Overall mortality, nonfatal myocardial infarction, stroke, and additional interventions were investigated. RESULTS: From January 2009 to January 2010, 918 consecutive patients were selected and followed until May 2015. They were separated into 4 groups: G1, 266 patients with diabetes and ventricular dysfunction; G2, 213 patients with diabetes without ventricular dysfunction; G3, 213 patients without diabetes and ventricular dysfunction; and G4, 226 patients without diabetes but with ventricular dysfunction. Groups 1, 2, 3, and 4, respectively, had a mortality rate of 21.6, 6.1, 4.2, and 10.6% (P < .001); nonfatal myocardial infarction of 5.3, .5, 7.0, and 2.6% (P < .001); stroke of .40, .45, .90, and .90% (P = NS); and additional intervention of 3.8, 11.7, 10.3, and 2.6% (P < .001). CONCLUSION: In this sample, regardless of the treatment previously received patients with or without diabetes and preserved ventricular function experienced similar outcomes. However, patients with ventricular dysfunction had a worse prognosis compared with those with normal ventricular function; patients with diabetes had greater mortality than patients without diabetes.Trial registration http://www.controlled-trials.com. Registration Number: ISRCTN66068876.

Effects of cardiac resynchronization therapy on muscle sympathetic nerve activity.

INTRODUCTION: Muscle sympathetic nerve activity (MSNA) is an independent prognostic marker in patients with heart failure (HF). Therefore, its relevance to the treatment of HF patients is unquestionable. OBJECTIVES: In this study, we investigated the effects of cardiac resynchronization therapy (CRT) on MSNA response at rest and during exercise in patients with advanced HF. METHODS: We assessed 11 HF patients (51 ± 3.4 years; New York Heart Association class III-IV; left ventricular ejection fraction 27.8 ± 2.2%; optimal medical therapy) submitted to CRT. Evaluations were made prior to and 3 months after CRT. MSNA was performed at rest and during moderate static exercise (handgrip). Peak oxygen consumption (VO2 ) was evaluated by means of cardiopulmonary exercise test. HF patients with advanced NYHA class without CRT and healthy individuals were also studied. RESULTS: CRT reduced MSNA at rest (48.9 ± 11.1 bursts/min vs 33.7 ± 15.3 bursts/min, P < 0.05) and during handgrip exercise (MSNA 62.3 ± 13.1 bursts/min vs 46.9 ± 14.3 bursts/min, P < 0.05). Among HF patients submitted to CRT, the peak VO2 increased (12.9 ± 2.8 mL/kg/min vs 16.5 ± 3.9 mL/kg/min, P < 0.05) and an inverse correlation between peak VO2 and resting MSNA (r = -0.74, P = 0.01) was observed. CONCLUSIONS: In patients with advanced HF and severe systolic dysfunction: (1) a significant reduction of MSNA (at rest and during handgrip) occurred after CRT, and this behavior was significantly superior to HF patients receiving only medical therapy; (2) MSNA reduction after CRT had an inverse correlation with O2 consumption outcomes.

Sudden cardiac death in Brazil: study based on physicians' perceptions of the public health care system.

BACKGROUND: There are no available statistical data about sudden cardiac death in Brazil. Therefore, this study has been conducted to evaluate the incidence of sudden cardiac death in our population and its implications. METHODS: The research methodology was based on Thurstone's Law of Comparative Judgment, whose premise is that the more an A stimulus differs from a B stimulus, the greater will be the number of people who will perceive this difference. This technique allows an estimation of actual occurrences from subjective perceptions, when compared to official statistics. Data were collected through telephone interviews conducted with Primary and Secondary Care physicians of the Public Health Service in the Metropolitan Area of São Paulo (MASP). RESULTS: In the period from October 19, 2009, to October 28, 2009, 196 interviews were conducted. The incidence of 21,270 cases of sudden cardiac death per year was estimated by linear regression analysis of the physicians' responses and data from the Mortality Information System of the Brazilian Ministry of Health, with the following correlation and determination coefficients: r = 0.98 and r(2) = 0.95 (95% confidence interval 0.8-1.0, P < 0.05). The lack of waiting list for specialized care and socioadministrative problems were considered the main barriers to tertiary care access. CONCLUSIONS: The incidence of sudden cardiac death in the MASP is high, and it was estimated as being higher than all other causes of deaths; the extrapolation technique based on the physicians' perceptions was validated; and the most important bureaucratic barriers to patient referral to tertiary care have been identified. (PACE 2012; 35:1326-1331).

Prevenção secundária da morte súbita: importância do marcapasso definitivo prévio ao implante de cardioversor-desfibrilador implantável (CDI) na sobrevida de pacientes com miocardiopatia chagásica / The relevance of previous permanent pacemaker implant in the survival actuarial curve of chagaapóstrofos ICD patients

Objetivo: Avaliar a importância clínica da presença de marcapasso definitivo (MPD) previamente ao implante de CDI de nossa instituição, foram selecionados 275 submetidos a implante de CDI para prevenção secundária de morte súbita cardíaca (MSC), agrupados de acordo com a cardiomiopatia de base e a presença de MPD prévio ao implante de CDI. As variáveis analisadas foram: sexo, idade, CF-NYHAA, medicações, ritmo cardíaco, FEVE e TVNS. Para análise estatística, utilizou-se o método de Kaplan Meier e o teste de log-rank. Resultados: A amostra reduzida de pacientes com consistentes...

Biventricular pacing improves clinical behavior and reduces prevalence of ventricular arrhythmia in patients with heart failure.

PURPOSE: To analyze the influence of biventricular pacing (BP) on clinical behavior, ventricular arrhythmia (VA) prevalence, and left ventricular ejection fraction (LV EF) by gated ventriculography. METHODS: Twenty-four patients with left bundle branch block (LBBB) and NYHA class III and IV underwent pacemaker implantation and were randomized either to the conventional or BP group, all receiving BP after 6 months. RESULTS: Sixteen patients were in NYHA class IV (66.6%) and 8 were in class III (33.4%). After 1-year follow-up, 14 patients were in class II (70%) and 5 were in class III (25%). Two sudden cardiac deaths occurred. A significant reduction in QRS length was found with BP (p=0.006). A significant statistical increase, from a mean of 19.13 +/- 5.19% (at baseline) to 25.33 +/- 5.90% (with BP) was observed in LVEF Premature ventricular contraction prevalence decreased from a mean of 10,670.00 +/- 12,595.39 SD or to a mean of 3,007.00 +/- 3,216.63 SD PVC/24 h with BP (p<0.05). Regarding the hospital admission rate over 1 year, we observed a significant reduction from 60. To 16 admissions with BP (p<0.05). CONCLUSION: Patients with LBBB and severe heart failure experienced, with BP, a significant NYHA class and LVEF improvement. A reduction in the hospital admission rate and VA prevalence also occurred.

Biventricular pacing improves clinical behavior and reduces prevalence of ventricular arrhythmia in patients with heart failure

PURPOSE: To analyze the influence of biventricular pacing (BP) on clinical behavior, ventricular arrhythmia (VA) prevalence, and left ventricular ejection fraction (LV EF) by gated ventriculography. METHODS: Twenty-four patients with left bundle branch block (LBBB) and NYHA class III and IV underwent pacemaker implantation and were randomized either to the conventional or BP group, all receiving BP after 6 months. RESULTS: Sixteen patients were in NYHA class IV (66.6 per cent) and 8 were in class III (33.4 per cent). After 1-year follow-up, 14 patients were in class II (70 per cent) and 5 were in class III (25 per cent). Two sudden cardiac deaths occurred. A significant reduction in QRS length was found with BP (p=0.006). A significant statistical increase, from a mean of 19.13 ñ 5.19 per cent (at baseline) to 25.33 ñ 5.90 per cent (with BP) was observed in LVEF Premature ventricular contraction prevalence decreased from a mean of 10,670.00 ñ 12,595.39 SD or to a mean of 3,007.00 ñ 3,216.63 SD PVC/24 h with BP (p<0.05). Regarding the hospital admission rate over 1 year, we observed a significant reduction from 60. To 16 admissions with BP (p<0.05). CONCLUSION: Patients with LBBB and severe heart failure experienced, with BP, a significant NYHA class and LVEF improvement. A reduction in the hospital admission rate and VA prevalence also occurred.

Marcapassos dotados de sensor mecânico. Experiência acumulada em seguimento tardio / Long term follow-up in pacemakers withvibrations sensing

Objetivo: Avaliar o comportamento do sistema de estimulaçäo de câmara única responsivo em freqüência dotado de sensor mecânico, em seguimento clínico tardio. Casuística e Métodos: No período de setembro de 1986 e abril de 1989, 70 pacientes foram submetidos a implante de marcapasso com biosensor mecânico. Em 64 (91,9%) do modelo implantado foi Activitrax I e em 6 (8,1%) Activitrax II. Trinta e um pacientes (44,4%) eram do sexo masculino e a média de idade foi de 51,2 anos. Cinqüenta e um pacientes (72,9%) submeteram-se a implante por bloqueio atrioventricular total, 11 (15,7%) por disfunsäo do nó sinusal, um (1,4%) por disfunçäo binodal e um (1,4%) para suporte terapêutico de arritmia. A etiologia foi chagásica em 31,4%, miocardiosclerótica da junçäo atrioventricular em 5,8%) e idiopática em 11,5%. O grupo foi submetido a avaliaçöes clínicas, eletrônicas do marcapasso e a exames complementares: ecocardiograma, ECG dinâmico, teste ergométrico e ergoespirométrico. O seguimento médio foi de 19,6 meses. Resultados: Avaliaçöes clínicas: melhora da classe funcional de ICC em 86% dos pacientes. Näo ocorreram síncopes ou óbitos de causa cardíaca. Ecocardiograma: melhora na fraçäo de ejeçäo em 42% dos pacientes. ECG dinâmico: resposta de freqüência adequada em 94,3% dos pacientes. Teste ergométrico: freqüência submáxima atingida em 65,6% (boa resposta cronotrópica). Ergoespirometria: melhora do consumo de oxigênio em 75% dos casos etudados. Avaliaçöes eletrônicas: ausência de disfunçäo do gerador, complicaçöes em 18% dos casos todas corrigidas por reprogramaçäo. Conclusäo. O sistema de estimulaçäo da camâra única dotado de sensor mecânico mostrou-se seguro, eficaz e apresentou baixo índice de complicaçöes

Purpose: To evaluate the behavior of single chamber stimulation system, rate responsive with vibration sensing, taking into consideration the results of long term clinical follow-up. Patients and Methods: From september 1986 to april 1989, 70 patients received pacemakers with vibration sensing. Sixty fou rpatients (91.9%) implan-ted Activitrax I model and six (8.1%) Activitrax II. Thirty-one (44.3%) were men and the mean age was 51.2 years. Fifty-one patients (72.9%) had complete atrioventricular block, 11 (15.7%) sinus node dysfunction, one (1.4%) sinus node and atrioventricular disease, and one (1,4%)for therapeutic support of arrhythmia. The etiology of these dysfunctions were Chagas' disease in 31.4%, myocardiosclerosis in 35.7%, post-operative in 15.6%, post-av node fulguration in 5.8% and idiopathic in 11.5%. The group was submitted to clinic and electronic evaluezion and laboratory examinations: echocardiogram, dynamic ECG, stress test and ergoespirometric test. The meanfollow-up as 19.6 months. Results: Clinic evaluations: decrease in congestive heart failure functional class in 86% of the patients. No recurrence of syncopes and no cardiac deaths. Echocardiogram: increase in ejection fraction in 42% of patients. Dynamic ECG: appropriate rate response in 94.3% of patients (good cronotropic response). Ergoespirometry: increase in oxygen consumption in 75% of studied cases, Electronic evaluation: absence of generator dysfunction; complications in 18% of cases, all corrected by reprogramation. Conclusion: The single chamber cardiac stimulation system with vibration sensing showed safety, efficacy and low rate of complications.