RESUMEN
AIM: To investigate the relationship between serum content of n-3 polyunsaturated fatty acids (PUFA) and the incidence of ventricular arrhythmias in patients with an implantable cardioverter defibrillator (ICD). METHODS: We included 98 patients with ischaemic heart disease and an ICD. The numbers of ventricular fibrillation (VF) and ventricular tachycardia (VT) events were assessed during a 12-month period and related to the concentration of n-3 PUFA in serum phospholipids. RESULTS: Patients with more than one arrhythmic event had significantly lower n-3 PUFA levels compared with patients without arrhythmias (mean 7.1% vs 9.2%, P<0.01). Dividing the patients into quintiles according to their n-3 PUFA level those with the lowest content of n-3 PUFA had more ventricular arrhythmias than patients with the highest concentration of n-3 PUFA (mean 1.3 event vs 0.2 event, P<0.05). CONCLUSION: Patients with a low content of n-3 PUFA in serum had a higher incidence of ventricular arrhythmias compared with patients with high serum levels of n-3 PUFA. The data suggest that the protection offered by n-3 PUFA against sudden cardiac death observed in previous studies is mediated by a direct antiarrhythmic effect of n-3 PUFA.
Asunto(s)
Desfibriladores Implantables , Ácidos Grasos Omega-3/sangre , Isquemia Miocárdica/complicaciones , Taquicardia Ventricular/sangre , Fibrilación Ventricular/sangre , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Isquemia Miocárdica/sangre , Isquemia Miocárdica/terapiaRESUMEN
BACKGROUND: recent short-term observations have shown an improvement in cardiac function and heart failure symptoms from atrio-biventricular pacing. This study was designed to assess the safety and feasibility of an atrio-biventricular transvenous pacing system, and examine the long-term effects of cardiac resynchronization in patients with advanced heart failure and ventricular conduction abnormalities. METHODS AND RESULTS: between August, 1997 and November, 1998, 103 patients received a cardiac resynchronization system (CRS) consisting of a pulse generator interfaced with an atrio-biventricular lead system, including a lead designed for left ventricular (LV) pacing via cardiac veins. Baseline evaluation included 12-lead electrocardiogram, estimation of New York Heart Association (NYHA) functional class, assessment of quality of life (QOL), and distance covered during a 6-min walk (6-MW). Detailed echocardiographic data were also collected in a subset of 46 patients. Measurements were repeated in all surviving patients at 1, 3, 6 and 12 months after implantation of the CRS. A single, self-limiting procedure-related complication occurred. Over a follow-up of 12 months, 21 patients died. The 12-month actuarial survival was 78% (CI 70-87%). Nine surviving patients were withdrawn from the study during long-term follow-up for miscellaneous reasons. At each point of follow-up, a significant shortening of QRS duration was measured. In addition, significant improvements were observed in mean NYHA functional class, 6-MW and QOL score. In the 46 patients with complete echocardiographic data, LV ejection fraction increased from 21.7+/-6.4% at baseline to 26.1+/-9.0% at last follow-up (P = 0.006), LV end diastolic dimension decreased from 72.7+/-9.2 to 71.6+/-9.1 mm (P = 0.233), interventricular mechanical delay decreased from 27.5+/-32.1 to 20.3+/-25.5 ms (P = 0.243), mitral regurgitation apical four-chamber area decreased from 7.66+/-5.5 to 6.69+/-5.9 cm(2) (P = 0.197), and left ventricular filling time increased from 363+/-127 to 408+/-111 ms (P = 0.002). CONCLUSIONS: long-term cardiac resynchronization can be safely and reliably achieved by transvenous atrial synchronized right and left ventricular pacing. These changes were accompanied by clinically relevant improvements in functional status and QOL, as well as a measurable increase in LV performance. The outcome of randomised controlled trials is awaited.
Asunto(s)
Estimulación Cardíaca Artificial/métodos , Cardiomiopatía Dilatada/terapia , Anciano , Análisis de Varianza , Bradicardia/terapia , Estimulación Cardíaca Artificial/efectos adversos , Cardiotónicos/uso terapéutico , Electrocardiografía , Prueba de Esfuerzo , Estudios de Factibilidad , Femenino , Humanos , Masculino , Marcapaso Artificial , Estudios Prospectivos , Calidad de Vida , Seguridad , Resultado del TratamientoRESUMEN
OBJECTIVE: The reproducibility of QT interval measurements is low, even for the mean QT interval based on the standard ECG. In this study we analyzed whether the reproducibility of the mean weighed QT interval was better than the simple mean QT interval. The weighing was based on the amplitude of the T wave or the slope of the steepest tangent on the terminal part of the T wave. MATERIAL AND METHODS: 12-lead ECGs of 130 postmyocardial infarction patients were obtained. The QT intervals were measured by the tangent-method on two occasions by the same observer Mismatch QT intervals were defined as QT intervals that were measured at only one occasion. Sixteen ECGs were rejected. The data were split into 34 and 80 ECGs for optimization and validation of the weighing, respectively. The weighed QT dispersion was calculated as the weighed mean of the three longest minus the weighed mean of the three shortest QT intervals. RESULTS: Weighing with the slope increased the reproducibility by 41% (P = 3 10(-6)), but weighing with the amplitude reduced it by 20% (P = 0.02). However, if measurements with errors above 75 ms were rejected, weighing with the slope or the amplitude increased the reproducibility with 26% and 20% (P = 0.02), respectively. Weighing did not change the reproducibility of the weighed QT dispersion. CONCLUSION: Weighing with the slope improved the reproducibility of the mean weighed QT interval. However, if measurements with errors above 75 ms were rejected, weighing with the amplitude also increased the reproducibility. Weighing did not change the reproducibility of the weighed QT dispersion. Weighing is particularly efficient at reducing the negative impact of mismatch QT intervals on the reproducibility.
Asunto(s)
Electrocardiografía/métodos , Procesamiento de Imagen Asistido por Computador , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Infarto del Miocardio/fisiopatologíaRESUMEN
BACKGROUND: The QT intervals accuracy for predicting arrhythmic death varies between studies, possibly due to differences in the selection of the lead used for measurement of the QT interval. The purpose of this study was to analyze the prognostic accuracy of all known ways to select the lead. METHODS AND RESULTS: Three institutions that used different methods for measuring QT intervals provided their QT databases. They included more than 3500 twelve-lead surface ECGs. The data represented low- and high-risk patients of the normal population (survivors vs dead from cardiovascular causes), acute myocardial infarction (survivors versus death from all causes) and remote myocardial infarction (with vs without a history of ventricular arrhythmia). The prognostic accuracy was defined as the area under the Receiver Operator Curve (ROC-area). The most accurate standard leads were I and aVL and the least accurate was AVR. The most accurate precordial lead was V4. The prognostic accuracy of the longest QT interval was higher than for any standard lead. The prognostic accuracy of the mean of the three longest QT intervals was equal to or slightly lower than for the longest QT interval. CONCLUSIONS: The highest prognostic accuracy is obtained with the longest QT interval. The accuracies of the lead selection methods are so different that it can explain a substantial part of the differences between otherwise similar studies in the literature. We recommend the use of the mean value of the three longest QT intervals.