Effect of a hypoglycemic agent on ischemic preconditioning in patients with type 2 diabetes and stable angina pectoris.

OBJECTIVE: Ischemic preconditioning is an increased tolerance to myocardial ischemia during the second of two consecutive exercise tests. ATP-sensitive K(+) channel blockers, such as glinides and sulfonylurea drugs, can induce loss of ischemic preconditioning. This study aimed to investigate the effects of repaglinide, a hypoglycemic agent with an affinity for myocardial ATP-sensitive K (+)channels, on the results of consecutive exercise tests in patients with diabetes and multivessel coronary artery disease. METHODS: Forty-two patients with type 2 diabetes and chronic stable angina pectoris, and two-vessel or three-vessel disease participated in this study. The patients underwent two consecutive treadmill exercise tests (phase 1). On the day after these exercise tests, 2 mg of oral repaglinide was given to the patients. One week later, two exercise tests were repeated consecutively (phase 2). RESULTS: All patients achieved 1.0-mm ST-segment depression during the four exercise tests (T1, T2, T3, and T4). In phase 2, seven patients improved in time to onset of 1.0-mm ST-segment depression. The worsening of the time to onset of 1.0-mm ST-segment depression in phase 2 demonstrated ischemic preconditioning block in 83.3% of patients (P=0.0001). Even the postexercise electrocardiographic parameters (ST-segment depression morphology and magnitude and arrhythmias) were significantly different between the groups with and without pharmacologic ischemic preconditioning block (P=0.031). CONCLUSIONS: Repaglinide, an oral hypoglycemic agent with ATP-sensitive K(+) channel-blocker activity, eliminated the myocardial ischemic preconditioning in patients with coronary disease and diabetes.

Radiofrequency catheter ablation of premature ventricular contractions originating in the right ventricular outflow tract.

OBJECTIVES: To evaluate if radiofrequency catheter ablation is an effective procedure for the treatment of right ventricular outflow tract premature ventricular contractions (RVOT-PVC) and ascertain if it results in an improvement of symptoms. METHODS: A prospective study with 30 consecutive patients (mean age 40 +/- 13 years, 25 females), with no apparent structural cardiopathy, with very frequent (mean density of 1,263 +/- 593/h) RVOT-PVC, symptomatic for more than one year (mean = 74 months) and resistant to antiarrhythmic drugs (3 +/- 1.7, including beta-blockers), who underwent radiofrequency catheter ablation. RESULTS: After the first procedure, there were 23 initial successful cases (76.6%) and 7 initial failures (23.4%). Four patients experienced relapses, two of whom did not undergo the second procedure. The second procedure was carried out in 9 patients (7 initial failures and 2 relapses), and there was success in 5 additional patients, one of them by epicardial access. The final success rate was 80% (24/30), and there were no major complications. After a mean follow-up of 14 +/- 6 months, in the successful group there was a reduction greater than 90% in density of premature ventricular contractions (PVC) (24/24; p<0.0001) and a resulting absence of symptoms in the majority of patients (23/24; p<0.001). CONCLUSION: Radiofrequency catheter ablation is a safe and effective treatment for patients with persistent and symptomatic PVC with RVOT morphology.

The effects of glibenclamide, a K(ATP) channel blocker, on the warm-up phenomenon.

BACKGROUND: The warm-up phenomenon observed after the second of two sequential exercise tests is characterized by an increased time to ischemia and ischemic threshold, and the latter is related to ischemic preconditioning. Previous studies have demonstrated that a single dose of glibenclamide, a cardiac ATP-sensitive K (K(ATP)) channel blocker, prevents ischemic preconditioning. This study aimed to investigate the effects of chronic treatment with glibenclamide during two sequential exercise tests. METHODS: Forty patients with angina pectoris were divided into three groups: 20 nondiabetics (NDM), 10 patients with diabetes in treatment with glibenclamide (DMG) and 10 diabetic patients with other treatments (DMO). All patients underwent two consecutive exercise tests. RESULTS: Heart rate and rate-pressure product at 1.0 mm ST-segment depression significantly increased during the second exercise test in NDM group (121.3+/-16.5 vs 127.3+/-15.3 beats/min, P<0.001, and 216.7+43.1 vs 232.1+/-43.0 beats.min-1.mmHg.10(2), P<0.001), and in DMO group (114.1+/-19.6 vs 119.6+/-18.1 beats/min, P=0.001, and 199.8+/-36.6 vs 222.2+/-29.2 beats.min-1.mmHg.10(2), P=0.019), but it did not change in patients in DMG group (130.7+/-14.5 vs 132.1+/-4.7 beats/min, P=ns, and 251.7+/-47.2 vs 250.3+/-42.8 beats.min-1.mmHg.10(2), P=ns). In the three groups, NDM, DMO, and DMG, the time to 1.0 mm ST-segment depression during the second exercise test was greater than during the first (225.0+/-112.5 vs 267.0+/-122.3 seconds, P=0.006; 187.5+/-54.0 vs 226.5+/-74.6 seconds, P=0.029 and 150.0+/-78.7 vs 186.0+/-81.9 seconds, P<0.001). CONCLUSION: The chronic use of glibenclamide may have mediated the loss of preconditioning benefits in the warm-up phenomenon, probably through its KATP channel-blocker activity, but without acting upon the tolerance to exercise.

Late coronary artery recanalization effects on left ventricular remodelling and contractility by magnetic resonance imaging.

AIMS: To assess the recanalization effects of post-myocardial infarction (MI) on left ventricular (LV) remodelling and contractility in relation to conservative therapy. METHODS AND RESULTS: Thirty-six patients with occluded infarct-related artery between 12 h and 14 days post-anterior MI were randomized to percutaneous coronary intervention (PCI group) or conservative therapy (no-PCI group). Magnetic resonance imaging was performed at enrollment and after 6 months. The left ventricle was divided into infarct, adjacent, and remote segments. There was no difference in relation to LV volume between groups at the 6 month follow-up. Change in LV ejection fraction was favourable to the PCI group: 5.00% vs. -0.76%, P=0.012. Change in circumferential shortening (Ecc) of the remote segments in the PCI group was significantly better than in the no-PCI group: -1.67+/-6.30% vs. 0.29+/-6.02%, P<0.001. Infarct size and LV mass were similar between groups. CONCLUSIONS: Late recanalization improved LV ejection fraction and myocardial contractility in late follow-up, but did not change the ventricular volumes. Improvement in the left ventricle global and regional contractility may benefit the long-term outcome in post-MI patients with sustained patency of the infarct-related artery.

Ablação com radiofreqüência de extra-sístoles da via de saída do ventrículo direito / Radiofrequency catheter ablation of premature ventricular contractions originating in the right ventricular outflow tract

OBJETIVOS: Avaliar se a ablação com radiofreqüência é um procedimento eficiente para o tratamento das extra-sístoles da via de saída do ventrículo direito (EVSVD), e se resulta em melhora dos sintomas. MÉTODOS: Estudo prospectivo, com 30 pacientes consecutivos (idade média de 40±13 anos, 25 do sexo feminino), sem cardiopatia estrutural aparente, com EVSVD, muito freqüentes (densidade média de 1.263±593/h), sintomáticos por mais de 1 ano (média =74 meses) e refratários aos fármacos antiarrítmicos (3±1,7, incluindo os beta-bloqueadores), que foram submetidos à ablação com radiofreqüência. RESULTADOS: Após o primeiro procedimento, houve 23 sucessos iniciais (76,6 por cento) e 7 iniciais insucessos (23,4 por cento). Quatro pacientes tiveram recorrências, sendo que dois desses não se submeteram ao segundo procedimento. O segundo procedimento foi realizado em 9 pacientes (7 insucessos iniciais e 2 recorrências), e o sucesso ocorreu em 5 pacientes adicionais, sendo 1 caso por acesso epicárdico. A taxa de sucesso final foi de 80 por cento (24/30), e nenhuma complicação maior ocorreu. Após um seguimento médio de 14±6 meses, no grupo de sucesso final houve uma redução de mais de 90 por cento na densidade das extra-sístoles(24/24; p<0,0001) e resultante ausência de sintomas na maioria dos pacientes (23/24; p<0,001). CONCLUSÃO: A ablação com radiofreqüência é um tratamento seguro e eficaz para os pacientes com extra-sístoles persistentes e sintomáticas com morfologia do trato de saída do ventrículo direito.

OBJECTIVES: To evaluate if radiofrequency catheter ablation is an effective procedure for the treatment of right ventricular outflow tract premature ventricular contractions (RVOT-PVC) and ascertain if it results in an improvement of symptoms. METHODS: A prospective study with 30 consecutive patients (mean age 40 ± 13 years, 25 females), with no apparent structural cardiopathy, with very frequent (mean density of 1,263 ± 593/h) RVOT-PVC, symptomatic for more than one year (mean = 74 months) and resistant to antiarrhythmic drugs (3 ± 1.7, including beta-blockers), who underwent radiofrequency catheter ablation. RESULTS: After the first procedure, there were 23 initial successful cases (76.6 percent) and 7 initial failures (23.4 percent). Four patients experienced relapses, two of whom did not undergo the second procedure. The second procedure was carried out in 9 patients (7 initial failures and 2 relapses), and there was success in 5 additional patients, one of them by epicardial access. The final success rate was 80 percent (24/30), and there were no major complications. After a mean follow-up of 14 ± 6 months, in the successful group there was a reduction greater than 90 percent in density of premature ventricular contractions (PVC) (24/24; p<0.0001) and a resulting absence of symptoms in the majority of patients (23/24; p<0.001). CONCLUSION: Radiofrequency catheter ablation is a safe and effective treatment for patients with persistent and symptomatic PVC with RVOT morphology.

Contribuiçäo do monitor de eventos no diagnóstico de sintomas / The contribution of the loop memory ECG recorder to the diagnosis of symptoms

OBJETIVO: A avaliar o poder de contribuiçäo do monitor de enventos sintomáticos no esclarecimento de sintomas. MÉTODOS: Foram estudados 64 pacientes encaminhados para esclarecimento de sintomas e que já haviam sido submetidos à gravaçäo com Holter. Foram monitorizados, durante 15 dias, com gravador com memória circular com capacidade de registrar uma derivaçäo do ECG (CM5), antes e após ativado pelo paciente. Na vigência de sintomas, o paciente acionava um comando do gravador que provocava a retençäo do sinal do ECG, que era, posteriormente, transmitido a uma central via telefone. Resultados: Em dois pacientes näo foi possível a realizaçäo completa da monitorizaçäo, nos restantes, sintomas que motivaram a indicaçäo do exame foram: palpitaçöes ( 67,7 "por cento"), tonturas (32,3 "por cento"), síncopes(29 "por cento") e outros (30,6 "por cento"). Em 85,5 "por cento" dos pacientes houve relato de sintomas, sendo que em 62,2 "por cento" houve registros de alteraçöes eletrocardiográficas, relacionadas aos sintomas: taquicardia sinusal, 45,5 "por cento"; extra-sístoles, 30,3 "por cento"; taquicardia supraventricualar, 21,2 "por cento"; 21,2 "por cento" taquicadia ventricular, 3 "por cento" e bloqueio atrioventricular, 3 "por cento". A primeira transmissäo motivada por sintomas ocorreu: 35,5 "por cento" no 1 primeiro dia, 33,9 "por cento" do 2 "segundo" ao 5 "quinto", 12,9 "por cento" do 6 "sexto" ao 10 "decimo" e 3,2 "por cento" 11"décimo primeiro" ao 15 "décimo quinto". Nos pacientes onde a gravaçäo com Holter näo permitiu esclarecimentos, o gravador de eventos registrou sintomas em 35,5 "por cento". CONCLUSÄO: Trata-se de métodos bem aceito pelos pacientes e capaz de produzir aumento sgificativo no esclarecimento de síntomas em relaçäo ao Holer.

Detecçäo do miocárdio viável: estudo de perfusäo, antes e após a cirurgia de revascularizaçäo em portadores de infarto do miocárdio / Detection of the viable myocardium: a perfusion scintigraphic study, before and after coronary bypass surgery in myocardial infarction patients

Objective - To compare single-photon-emission computed tomography (SPECT) imaging scans using (201)Tl and (99m)Tc-MIBI in detection of viable myocardium, in regions compromised by infraction. Methods - Thirty-two (59.3+9.8 years old and 87 per cent male) myocardial infarction patients were studied. All had Q waves on the ECG and left ventricle ejection fraction of <50 per cent. They underwent coronary and left ventricle angiographies and SPECT before (including (201)Tl reinjection) and after coronary artery bypass surgery (CABG). Improvement in perfusion observed after surgery was considered the gold standard for myocardial viability. Results - Among 102 studied regions of the heart, there were 40 (39.2 per cent) areas of transient perfusion defects in the conventional protocol with (201)Tl and 52 (51.0 per cent) after reinjection. Therefore, 12/62 (19.4 per cent) more viable regions were identified by reinjection. Using (99m)Tc-MIBI, only 14 (13.7 per cent) regions with transient defects were identified, all of which were seen also in (201)Tl protocols. After surgery, 49 of total of 93 regions analyzed (52.7 per cent) were viable. Sensitivity, specificity, accuracy, positive and negative prediction values were, respectively, (201)Tl SPECT scans-65.3 per cent, 90.9 per cent, 77.4 per cent, 88.9 per cent and 70.2 per cent, reinjection protocol with (201)Tl scans - 81.6 per cent, 81.8 per cent, 81.7 per cent, 83.3 per cent and 80.0 per cent; (99m)Tc-MIBI SPECT scans - 20.4 per cent, 90.9 per cent, 53.8 per cent, 71.4 per cent and 50.6 per cent. Logistic regression demonstrated that the reinjection protocol with (201)Tl was the best predictor of viability (P<0.001). Conclusion - Our data suggest the election of (201)Tl for viability studies, especially when using the reinjection protocol.

Relação entre o ECG convencional e a artéria coronária responsável no infarto agudo do miocárdio / The relationship between conventional ECG and the culprit coronary artery in acute myocardial infarct

PURPOSE--To evaluate electrocardiogram (ECG) in detecting acute myocardial infarction (AMI) during the first 12 hours of symptoms and its relationship to the culprit coronary artery. METHODS--We studied 68 patients aged 55.6 (30 to 76) years, 61 males, with AMI confirmed by elevated CKMB isoenzyme and cinecoronariography (CINE). In all of them we obtained two ECG: first (i), with < 12 hours of symptoms and a second, > or = 5 days during evolution. ECG were analyzed in order to disclose up and downward ST-T segments > or = 1 mm, new Q waves > or = 0.04 s and R/S > or = 1 plus downward ST-T segment in leads V1 and V2. Then we have done correlation between these and the culprit coronary lesions at CINE. RESULTS--The culprit coronary lesions were: right coronary artery (RCA) in 16, left circumflex (LC) in 26 and left anterior descending (LAD) in 31 cases. According to the ECG, the RCA determined inferior AMI in all patients and the LC only in 62 por cento of cases. Posterior AMI due to LC was seen in 81 por cento of cases at ECG and, associated with lateral AMI, in 52 por cento . Lone lateral AMI was seen in 5 por cento and true posterior in 14 por cento of cases, all of them due to LC. CONCLUSION--False negative ECG (i) in AMI is in fact due to LC occlusion which, frequently, causes posterior wall more then inferior wall myocardial infarction at ECG

Eletrocardiograma de alta resoluçäo na cardiopatia chagásica crônica / The signal average ECG in patients with chronic Chagas' heart disease

Foram estudados, por meio de eletrocardiograma de alta resoluçäo, 192 pacientes com cardiopatia chagásica crônica, sendo 96 (50 por cento) do sexo masculino. A idade variou entre 17 e 75 anso (média de 42,93.). O estudo objetivou estudar a prevalência de potencial tardio em portadores de cardiopatia chagásica crônica e sua relaçäo com taquicardia ventricular sustentada. De acordo com a presença ou a ausência de bloqueio de ramo e taquicardia ventricular sustentada foram constituídos 4 grupos. Admitiu-se a presença de potencial tardio, com filtro de 40H2, nos grupos sem bloquio de ramo, quando a duraçäo do QRS filtrado era . 110 ms, a duraçäo do sinal abaixo de 40 uV maior-igual 35ms e voltagem da raiz quadrada dos últimos 40 ms (VM40) maior-igual 20uV. Nos grupos com bloqueio de ramo considerou-se o VM 40 maior-igual 14UV como indicativo de potencial tardio. Resultados: nos grupos sem bloqueio de ramo o potencial tardio esteve presente em 21 (78 por cento) dos pacientes com taquicardia ventricular sustentada e em 22 (31 por cento) dos sem taquicardia ventricular sustentada (p < 0,001), com sensibilidade (S) 78 por cento, especificidade (E) 70 por cento e acurácia (Ac) 77 por cento. O potencial tardio esteve presente em 30 (48 por cento) dos pacientes sem taquicardia ventricular sustentada e em 20 (67 por cento) com taquicardia ventricular sustentada nos grupos com bloqueio de ramo (p=0,066), com S, 66 por cento; E, 52 por cento; e Ac, 57 por cento. No seguimento 12 (21 por cento) pacientes apresentaram recorrência de taquicardia ventricular sustentada: 91,6 por cento desses pacientes tinham potencial tardio. Ocorreram quatro óbtios sem relaçäo com eventos arrítmicos todos pertencentes ao grupo com bloqueio de ramo e sem taquicardia ventricular sustentada, e com potencial tardio ausente. Conclusöes: potencial tardio ocorreu em 77,7 por cento dos pacientes com taquicardia ventricular sustentada e sem bloqueio de ramo. Na ausência de bloqueio de ramo o eletrocardiograma de alta resoluçäo diferenciou pacientes com e sem taquicardia ventricular sustentada. nos grupos sem bloqueio de ramo observou-se S=70por cento e Ac=77 por cento. Nos grupos com bloqueio de ramo, em 66,6 por cento dos casos houve associaçäo entre potencial tardio e taquicardia ventricular sustentada. A recorrência de taquicardia ventricular sustentada esteve presente em 21 por cento dos casos e, desses, 91,6 por cento tinham potencial tardio.