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Biomedical subjects

E O Robles de Medina

Publications and source records attributed to E O Robles de Medina.

At least 19 recordsLinked to original sources
PubMed2001

Exercise performance in patients with end-stage heart failure after implantation of a left ventricular assist device and after heart transplantation: an outlook for permanent assisting?

OBJECTIVES: We sought to study exercise capacity at different points in time after left ventricular assist device (LVAD) implantation and subsequent heart transplantation (HTx). BACKGROUND: The lack of donor organs warrants alternatives for transplantation. METHODS: Repeat treadmill testing with respiratory gas analysis was performed in 15 men with a LVAD. Four groups of data are presented. In group A (n = 10), the exercise capacities at 8 weeks and 12 weeks after LVAD implantation were compared. In group B (n = 15), the data at 12 weeks are presented in more detail. In group C (n = 9), sequential analysis of exercise capacity was performed at 12 weeks after LVAD implantation and at 12 weeks and one year after HTx. In group D, exercise performance one year after HTx in patients with (n = 10) and without (n = 20) a previous assist device was compared. RESULTS: In group A, peak oxygen consumption (Vo2) increased from 21.3+/-3.8 to 24.2+/-4.8 ml/kg body weight per min (p < 0.003), accompanied by a decrease in peak minute ventilation/ carbon dioxide production (VE/Vco2) (39.4+/-10.1 to 36.3+/-8.2; p < 0.03). In group B, peak Vo2 12 weeks after LVAD implantation was 23.0+/-4.4 ml/kg per min. In group C, levels of peak Vo2 12 weeks after LVAD implantation and 12 weeks and one year after HTx were comparable (22.8+/-5.3, 24.6+/-3.3 and 26.2+/-3.8 ml/kg per min, respectively; p = NS). In group D, there appeared to be no difference in percent predicted peak Vo2 in patients with or without a previous LVAD (68+/-13% vs. 74+/-15%; p < 0.37), although, because of the small numbers, the power of this comparison is limited (0.45 to detect a difference of 10%). CONCLUSIONS: Exercise capacity in patients with a LVAD increases over time; 12 weeks after LVAD implantation, Vo2 is comparable to that at 12 weeks and one year after HTx. Previous LVAD implantation does not seem to adversely affect exercise capacity after HTx.

Adult↗
PubMed2001

Increased dispersion and shortened refractoriness caused by verapamil in chronic atrial fibrillation.

OBJECTIVES: The objective was to assess the effect ofverapamil on atrial fibrillation (AF) cycle length and spatial dispersion of refractoriness in patients with chronic AF. BACKGROUND: Previous studies have suggested that verapamil prevents acute remodeling by AF. The effects of verapamil in chronic AF are unknown. METHODS: During electrophysiologic study in 15 patients with chronic AF (duration >1 year), 12 unipolar electrograms were recorded from right atrial free wall, right atrial appendage and coronary sinus, along with monophasic action potential recordings from the right atrial appendage. The mean fibrillatory interval at each atrial recording site was used as an index for local refractoriness. Dispersion of refractoriness was calculated as the standard deviation of all local mean fibrillatory intervals expressed as a percentage of the overall mean fibrillatory interval. After baseline measurements, verapamil (0.075 mg/kg intravenous in 10 min) was infused and the measurements were repeated. RESULTS: After administration ofverapamil, mean fibrillatory intervals shortened by a mean of 16.6 +/- 3.3 ms (p < 0.001) at the right free wall, 15.0 +/- 3.5 ms (p < 0.001) at the appendage and 17.1 +/- 3.2 ms (p < 0.01) in the coronary sinus. Monophasic action potential duration decreased by 15.9 +/- 4.0 ms (p < 0.01). Dispersion of refractoriness increased in all patients from 3.8 +/- 0.8 to 5.1 +/- 1.8 (p < 0.001). A strong correlation between mean fibrillatory intervals and action potential duration was found, both before and after verapamil. CONCLUSIONS: Verapamil caused shortening of refractoriness and increase in spatial dispersion of refractoriness in patients with chronic AF. This implies that verapamil is not useful in reversing the remodeling process in these patients.

Aged↗
PubMed2000

The Octopus Study: rationale and design of two randomized trials on medical effectiveness, safety, and cost-effectiveness of bypass surgery on the beating heart.

The Octopus Study consists of two multicenter randomized clinical trials in which coronary artery bypass grafting on the beating heart (off-pump CABG) using the Utrecht Octopus Method is compared to intracoronary stent implantation and conventional CABG. The primary endpoint in the comparison of off-pump CABG versus stent implantation (OctoStent Trial) is medical effectiveness (i.e., absence of reintervention and major adverse cardiac and cerebrovascular events at 1 year after treatment). The primary endpoint in the comparison of off-pump CABG versus conventional CABG (OctoPump Trial) is cerebral safety (i.e., absence of cognitive deficits and cerebrovascular events at 3 months after treatment). Secondary endpoints in both trials include presence and severity of angina, quality of life, exercise capacity, and cost-effectiveness. A total of 560 patients will be enrolled. A random sample of 210 patients will undergo repeat angiography at 1 year to assess angiographic restenosis rate and graft patency. Including 1-year follow-up, the study will last for 3 years. Control Clin Trials 2000;21:595-609

Angioplasty, Balloon, Coronary↗
PubMed2000

Reduction of radiation exposure in the cardiac electrophysiology laboratory.

The purpose of this study was to determine the effects of various protective measures on patient and operator radiation dose levels in catheter ablation procedures. Catheter ablation procedures are associated with significant radiation levels. The patient's skin and operator radiation levels were measured (1) at baseline, (2) after primary beam filtration by 0.3-mm copper sheet and 2-mm aluminium plate and implementation of the LocaLisa system, and (3) after reduction of the left anterior oblique fluoroscopic pulse rate and installation of a lead glass screen. Additionally, a comparative analysis of radiation exposure levels was performed in the seven Dutch catheter ablation centers. Filtration of both primary beams resulted in a more than two-fold reduction in patient skin dose. Together with the LocaLisa system, this resulted in a six-fold reduction in patient and operator dose. As expected, lowering of the left anterior oblique pulse rate from 25 to 12.5 Hz reduced the corresponding patient skin dose with a factor 2 while the lead-glass protection caused an extra factor 2 reduction for the operator. Large differences were observed between fluoroscopy systems used for catheter ablation in the Netherlands. Depending on patient body mass and fluoroscopy system, patient skin dose varied between 0.2 and 8.4 Gy/hour. Proper measures may allow for a significant reduction of patient and operator radiation exposure in catheter ablation procedures. The large influence of body mass and equipment on patient's skin dose requires a more direct monitoring of skin dose than total fluoroscopy time.

Catheter Ablation↗
PubMed1999

Clinical application of an integrated 3-phase mapping technique for localization of the site of origin of idiopathic ventricular tachycardia.

BACKGROUND: Radiofrequency (RF) catheter ablation provides curative treatment for idiopathic ventricular tachycardia (VT). METHODS AND RESULTS: Nineteen consecutive patients with an idiopathic VT underwent RF catheter ablation. An integrated 3-phase mapping approach was used, consisting of the successive application of online 62-lead body surface QRS integral mapping, directed regional paced body surface QRS integral mapping, and local activation sequence mapping. Mapping phase 1 was localization of the segment of VT origin by comparing the VT QRS integral map with a database of mean paced QRS integral maps. Mapping phase 2 was body surface pace mapping during sinus rhythm in the segment localized in phase 1 until the site at which the paced QRS integral map matched the VT QRS integral map was identified (ie, VT exit site). Mapping phase 3 was local activation sequence mapping at the circumscribed area identified in phase 2 to identify the site with the earliest local endocardial activation (ie, site of VT origin). This site became the ablation target. Ten VTs were ablated in the right ventricular outflow tract, 2 at the basal LV septum, and 7 at the midapical posterior left ventricle. A high long-term ablation success (mean follow-up duration, 14+/-9 months) was achieved in 17 of the 19 patients (89%) with a low number of RF pulses (mean, 3.3+/-2.2 pulses per patient). CONCLUSIONS: This prospective study shows that integrated 3-phase mapping for localization of the site of origin of idiopathic VT offers efficient and accurate localization of the target site for RF catheter ablation.

Adult↗
PubMed1999

LocaLisa: new technique for real-time 3-dimensional localization of regular intracardiac electrodes.

BACKGROUND: Estimation of the 3-dimensional (3D) position of ablation electrodes from fluoroscopic images is inadequate if a systematic lesion pattern is required in the treatment of complex arrhythmogenic substrates. METHODS AND RESULTS: We developed a new technique for online 3D localization of intracardiac electrodes. Regular catheter electrodes are used as sensors for a high-frequency transthoracic electrical field, which is applied via standard skin electrodes. We investigated localization accuracy within the right atrium, right ventricle, and left ventricle by comparing measured and true interelectrode distances of a decapolar catheter. Long-term stability was analyzed by localization of the most proximal His bundle before and after slow pathway ablation. Electrogram recordings were unaffected by the applied electrical field. Localization data from 3 catheter positions, widely distributed within the right atrium, right ventricle, or left ventricle, were analyzed in 10 patients per group. The relationship between measured and true electrode positions was highly linear, with an average correlation coefficient of 0.996, 0.997, and 0.999 for the right atrium, right ventricle, and left ventricle, respectively. Localization accuracy was better than 2 mm, with an additional scaling error of 8% to 14%. After 2 hours, localization of the proximal His bundle was reproducible within 1.4+/-1.1 mm. CONCLUSIONS: This new technique enables accurate and reproducible real-time localization of electrode positions in cardiac mapping and ablation procedures. Its application does not distort the quality of electrograms and can be applied to any electrode catheter.

Bundle of His↗
PubMed1999

Accuracy of the LocaLisa system in catheter ablation procedures.

Estimation of the 3-dimensional (3D) position of ablation electrodes from fluoroscopic images is inadequate in the ablation of complex arrhythmogenic substrates. We developed a new technique for real-time 3D localization of intracardiac electrodes. Regular catheter electrodes are used as sensors for a high-frequency transthoracic electrical field, which is applied via standard skin electrodes. We investigated localization accuracy by comparing measured and true interelectrode distances between the tip and the 10th electrode of a decapolar catheter, and the tip and the 4th electrode of a quadripolar catheter during catheter ablation procedures. Long-term stability was analyzed by localization of the proximal His bundle before and after slow pathway ablation. Accuracy achieved with the 54-mm distance between the two outer electrodes of the decapolar catheters was 101% +/- 15%, 95% +/- 10%, and 97% +/- 8% in the right atrium, right ventricle, and left ventricle, respectively. During catheter ablation procedures, the measured distance between the tip and 4th electrode of the mapping catheter was 100% +/- 15% in atrial flutter, 100% +/- 12% in slow pathway ablation, and 100% +/- 14% in ablations for left ventricular tachycardia. After 2 hours, localization of the proximal His bundle was reproducible within 1.4 +/- 1.1 mm. The LocaLisa technique allows for reproducible, real-time nonfluoroscopic 3D visualization of standard mapping and ablation catheters and is sufficiently accurate for the creation of linear radiofrequency lesions. The freedom of catheter choice makes the LocaLisa system an invaluable tool in catheter mapping and ablation procedures.

Atrial Flutter↗
PubMed1998

Body surface mapping during pacing at multiple sites in the human atrium: P-wave morphology of ectopic right atrial activation.

BACKGROUND: The morphology and polarity of the P wave on 12-lead ECG are of limited clinical value in localizing ectopic atrial rhythms. It was the aim of this study to assess the spatial resolution of body surface P-wave integral mapping in identifying the site of origin of ectopic right atrial (RA) impulse formation in patients without structural atrial disease. METHODS AND RESULTS: Sixty-two-lead ECG recordings were obtained during RA pacing at 86 distinct endocardial sites in nine patients with normal biatrial anatomy. After P-wave integral maps were generated for each paced activation sequence, 17 groups with nearly identical map features were visually selected, and a mean P-wave integral map was computed for each group. Supportive statistical analysis to corroborate qualitative group selection was performed by assessment of (1) intragroup pattern uniformity by use of jackknife correlation coefficient analysis of the integral maps contained in each group and (2) intergroup pattern variability by use of the calculation of cross correlations between the 17 mean integral maps. The spatial resolution of paced P-wave body surface mapping in the right atrium was obtained by estimating the area size of endocardial segments with nearly identical P-wave integral maps by use of a biplane fluoroscopic method to compute the three-dimensional position of each pacing site. The latter approach yielded a mean endocardial segment size of 3.5+/-2.9 cm2 (range, 0.79 to 10.75 cm2). CONCLUSIONS: Use of the P-wave morphology on the 62-lead surface ECG in patients with normal biatrial anatomy allows separation of the origin of ectopic RA impulse formation into one of 17 different endocardial segments with an approximated area size of 3.5 cm2. This database of paced P-wave integral maps provides a versatile clinical tool to perform detailed noninvasive localization of right-sided atrial tachycardia before radiofrequency catheter ablation.

Adult↗
PubMed1998

Coronary artery bypass grafting without cardiopulmonary bypass using the octopus method: results in the first one hundred patients.

OBJECTIVE: Cardiopulmonary bypass and global cardiac arrest enable safe coronary artery bypass grafting but have adverse effects. In off-pump coronary bypass grafting, invasiveness is reduced, but anastomosis suturing is jeopardized by cardiac motion. Therefore the key to successful off-pump coronary bypass grafting is effective local cardiac wall stabilization. METHODS: We prospectively assessed the safety and efficacy of the Octopus tissue stabilizer (Medtronic, Inc., Minneapolis, Minn.) in the first 100 patients selected for off-pump coronary bypass via full or limited surgical access. To immobilize and expose the coronary artery, two suction paddles (-400 mm Hg), fixed to the operating table-rail by an articulating arm, stabilized the anastomosis site. RESULTS: One hundred forty-one grafts (96% arterial) were used to create 172 anastomoses (17% side-to-side), up to 4 per patient, on average 23 in the full access group (46 patients) and 1.2 in the limited access group (54 patients). Complications included conversion to cardiopulmonary bypass (2%), conversion from limited to full access (3%), myocardial infarction (4%), predischarge coronary reintervention (2%), and late coronary reintervention (1%). Median postoperative length of hospital stay was 4 days (limited access) or 5 days (full access). Rapid recovery allowed 96% of patients to resume social activities within 1 month. At the 6-month angiographic follow-up, 95% of anastomoses was patent. At the 2- to 22-month follow-up (mean, 13 months), 98 patients were in Canadian Cardiovascular Society class I and 2 patients were in class II. CONCLUSION: These results suggest that off-pump coronary artery bypass grafting with the Octopus tissue stabilizer is safe. Early clinical outcome and patency rates warrant a randomized study comparing this methods with conventional coronary bypass grafting.

Cardiopulmonary Bypass↗
PubMed1998

Electrocardiographic identification of abnormal ventricular depolarization and repolarization in patients with idiopathic ventricular fibrillation.

OBJECTIVES: We sought to gain more insight into the arrhythmogenic etiology of idiopathic ventricular fibrillation (VF) by assessing ventricular depolarization and repolarization properties by means of various electrocardiographic (ECG) techniques. BACKGROUND: Idiopathic VF occurs in the absence of demonstrable structural heart disease. Abnormalities in ventricular depolarization or repolarization have been related to increased vulnerability to VF in various cardiac disorders and are possibly also present in patients with idiopathic VF. METHODS: In 17 patients with a first episode of idiopathic VF, 62-lead body surface QRST integral maps, QT dispersion on the 12-lead ECG and XYZ-lead signal-averaged ECGs were computed. RESULTS: All subjects of a healthy control group had a normal dipolar QRST integral map. In patients with idiopathic VF, either a normal dipolar map (29%,), a dipolar map with an abnormally large negative area on the right side of the thorax (24%) or a nondipolar map (47%) were recorded. Only four patients (24%) had increased QT dispersion on the 12-lead ECG and late potentials could be recorded in 6 (38%) of 16 patients. During a median follow-up duration of 56 months (range 9 to 136), a recurrent arrhythmic event occurred in 7 patients (41%), all of whom had an abnormal QRST integral map. Five of these patients had late potentials, and three showed increased QT dispersion on the 12-lead ECG. CONCLUSIONS: In patients with idiopathic VF, ventricular areas of slow conduction, regionally delayed repolarization or dispersion in repolarization can be identified. Therefore, various electrophysiologic conditions, alone or in combination, may be responsible for the occurrence of idiopathic VF. Body surface QRST integral mapping may be a promising method to identify those patients who do not show a recurrent episode of VF.

Adult↗
PubMed1998

Low prevalence of coronary artery spasm in patients with normal coronary angiograms and unexplained ventricular fibrillation.

AIMS: The aetiology of ventricular fibrillation in patients without identifiable structural heart disease is unknown. Recently, high prevalence of silent ischaemia due to coronary artery spasm has been reported in such patients. However, in at least one report, all patients had non-critical coronary artery lesions. Identification of coronary artery spasm as the underlying aetiology of ventricular fibrillation has important therapeutic implications. METHODS AND RESULTS: We performed ergonovine provocation tests in 18 patients (14 males, and four females; mean age, 36 years) with documented ventricular fibrillation in the absence of identifiable structural heart disease who had undergone aborted sudden death. In group I (n = 7) ergonovine provocation tests were performed at a mean interval of 31 months (range 21-42 months) after the index episode. These patients had already received an implantable cardioverter defibrillator, after failed electrophysiologically guided antiarrhythmic therapy. In group II (n = 11) the ergonovine provocation test was performed prospectively as part of the diagnostic evaluation. All patients were off antiarrhythmic drugs, calcium entry or beta-adrenoceptor blockers at the time of the ergonovine provocation test. Ergonovine was administered intravenously as a bolus injection, beginning with 0.05 mg followed every 3 min by incremental doses up to a cumulative maximum dose of 0.45 mg. Predefined end-points were (1) recording of ischaemic ST segment shifts of > or = 1 mm in at least two corresponding leads of the 12-lead electrocardiogram; (2) induction of ventricular tachycardia or ventricular fibrillation; and (3) administration of a cumulative dose of 0.45 mg. A positive response to ergonovine was seen in only one patient (5%) in group I in whom there developed ST segment elevation without angina and a short burst of rapid ventricular tachycardia. CONCLUSIONS: This study found a low prevalence of coronary artery spasm in patients with aborted sudden death resulting from documented ventricular fibrillation and non-apparent underlying heart disease. All patients had normal coronary angiograms and a negative history for spontaneous episodes of chest pain. The mechanism of arrhythmogenesis in such patients remains largely unknown.

Adult↗
PubMed1997

[Minimally invasive arterial coronary bypass grafting: on beating heart and via smaller access].

Postoperative recovery after (arterial) coronary bypass grafting mostly takes several months because of the effects of the heart-lung machine and the cardioplegia which are mostly haematological, pneumological and neurological in nature. The morbidity can be reduced by operating on the beating heart and via smaller access. One possibility is the 'Octopus' method developed in Utrecht, which involves local fixation of the beating heart. The postoperative recovery of the first 45 patients was favourable.

Anastomosis, Surgical↗
PubMed1997

[Congenital long QT syndrome].

The long QT syndrome (LQTS) combines a prolonged QT interval with an enhanced risk of polymorphous ventricular arrhythmias that may lead to syncope and sudden cardiac death. It may be congenital or acquired (the latter sometimes caused by drugs). Congenital LQTS is a rare disease, usually discovered during the clinical evaluation of understood syncopes or at cardiological examination after an unexpected sudden cardiac death of a close relative. The syncope frequently occurs during physical exercise, fear or sudden loud noises. In patients with symptomatic LQTS, the mortality 10 years after the first syncope amounts to approximately 50%. A prolonged QT interval indicates abnormal repolarization or deceleration of the depolarization. An increase of the sympathetic tone, e.g. during physical exercise and emotions, causes prolongation of the QT interval. Congenital LQTS has been associated with genetic mutations, for instance on chromosomes 3 and 7. Treatment consists af administration of beta-blockers, sympathectomy and, if necessary, implantation of an automatic cardioverter/defibrillator.

Adrenergic beta-Antagonists↗
PubMed1997

The long QT syndrome: a novel missense mutation in the S6 region of the KVLQT1 gene.

The Romano Ward long QT syndrome (LQTS) has an autosomal dominant mode of inheritance. Patients suffer from syncopal attacks often resulting in sudden cardiac death. The main diagnostic parameter is a prolonged QT(c) interval as judged by electro-cardiographic investigation. LQTS is a genetically heterogeneous disease with four loci having been identified to date: chromosome 11p15.5 (LQT1), 7q35-36 (LQT2), 3p21-24 (LQT3) and 4q25-26 (LQT4). The corresponding genes code for potassium channels KVLQT1 (LQT1) and HERG (LQT2) and the sodium channel SCN5A (LQT3). The KVLQT1 gene is characterized by six transmembrane domains (S1-S6), a pore region situated between the S5 and S6 domains and a C-terminal domain accounting for approximately 60% of the channel. This domain is thought to be co-associated with another protein, viz. minK (minimal potassium channel). We have studied a Romano Ward family with several affected individuals showing a severe LQTS phenotype (syncopes and occurrence of sudden death). Most affected individuals had considerable prolongations of QT(c). By using haplotyping with a set of markers covering the four LQT loci, strong linkage was established to the LQT1 locus, whereas the other loci (LQT2, LQT3 and LQT4) could be excluded. Single-strand conformation polymorphism analysis and direct sequencing were used to screen the KVLQT1 gene for mutations in the S1-S6 region, including the pore domain. We identified a Gly-216-Arg substitution in the S6 transmembrane domain of KVLQT1. The mutation was present in all affected family members but absent in normal control individuals, providing evidence that the mutated KVLQT1-gene product indeed caused LQTS in this family. The mutated KVLQT1-gene product thus probably results in a dominant negative suppression of channel activity.

DNA Mutational Analysis↗
PubMed1997

Radiofrequency catheter ablation of AV nodal re-entrant tachycardia in scimitar syndrome.

A 70-year-old male is described who suffered from daily episodes of supraventricular tachycardia that was refractory to oral medical treatment since adolescence. Electrocardiographical and electrophysiological evaluation confirmed atrioventricular nodal re-entrant tachycardia (AVNRT). This arrhythmia commonly occurs in patients without concomitant heart disease. However, in this patient a variant form of the scimitar syndrome was found by coincidence at the age of 56 years. This report describes (1) the variant form of the scimitar syndrome, (2) the coexistence of AVNRT in scimitar syndrome, and (3) the feasibility of radiofrequency catheter ablation of AVNRT in the presence of this congenital anomaly.

Aged↗
PubMed1996

Cost-effectiveness of implantable defibrillator as first-choice therapy versus electrophysiologically guided, tiered strategy in postinfarct sudden death survivors. A randomized study.

BACKGROUND: Rising costs of health care, partly as a result of costly therapeutic innovations, are of concern to both the medical profession and healthcare authorities. The implantable cardioverter-defibrillator (ICD) is still not remunerated by Dutch healthcare insurers. The aim of this study was to evaluate the cost-effectiveness of early implantation of the ICD in postinfarct sudden death survivors. METHODS AND RESULTS: Sixty consecutive postinfarct survivors of cardiac arrest caused by ventricular tachycardia or fibrillation were randomly assigned either ICD as first choice (n = 29) or a tiered therapy starting with antiarrhythmic drugs and guided by electrophysiological (EP) testing (n = 31). Median follow-up was 729 days (range, 3 to 1675 days). Fifteen patients died, 4 in the early ICD group and 11 in the EP-guided strategy group (P = .07). For quantitative assessment, the cost-effectiveness ratio was calculated for both groups and expressed as median total costs per patient per day alive. Because effectiveness aspects other than mortality are not incorporated in this ratio, other factors related to quality of life were used as qualitative measures of cost-effectiveness. The cost-effectiveness ratios were $63 and $94 for the early ICD and EP-guided strategy groups, respectively, per patient per day alive. This amounts to a net cost-effectiveness of $11,315 per patient per year alive saved by early ICD implantation. Costs in the early ICD group were higher only during the first 3 months of follow-up, but as a result of the high proportion of therapy changes, including arrhythmia surgery and late ICD implantation, costs in the EP-guided strategy group became higher after that. Patients discharged with antiarrhythmic drugs as sole therapy had the lowest total costs. This subset, however, showed extremely high mortality, resulting in a poor cost-effectiveness ratio ($196 per day). Invasive therapies and hospitalization were the major contributors to costs. If quality-of-life measures are taken into account, the cost-effectiveness of early ICD implantation was even more favorable. Recurrent cardiac arrest and cardiac transplantation occurred in the EP-guided strategy group only, whereas exercise tolerance, total hospitalization duration, number of invasive procedures, and antiarrhythmic therapy changes were significantly in favor of early ICD implantation. CONCLUSIONS: In terms of cost-effectiveness, early ICD implantation is superior to the EP-guided therapeutic strategy in postinfarct sudden death survivors.

Anti-Arrhythmia Agents↗
PubMed1995

Randomized study of implantable defibrillator as first-choice therapy versus conventional strategy in postinfarct sudden death survivors.

BACKGROUND: In retrospective studies of sudden cardiac death survivors, the implantable cardioverter-defibrillator (ICD) compares favorably with medical and surgical therapy. Thus, use of the conventional strategy of starting treatment with antiarrhythmic drugs (AD), at least in certain patient categories, may be questionable. The goal of this study was to analyze the effectiveness of ICD implantation as first-choice therapy versus the conventional therapeutic strategy of starting with AD. METHODS AND RESULTS: Sixty consecutive survivors of cardiac arrest caused by old myocardial infarction were randomly assigned early ICD implantation (n = 29) or conventional therapy (n = 31). Baseline characteristics were similar in the two groups. Therapy in each patient was always guided by ECG monitoring, exercise testing, and programmed electrical stimulation (PES). Primary end points (main outcome events, including death, recurrent cardiac arrest, and cardiac transplantation), number of invasive procedures and antiarrhythmic therapy changes, and duration of hospitalization were compared. Median follow-up was 24 months (mean, 27 months). In the early ICD group, 4 patients (14%) died, all of cardiac causes. In the conventional group, 20 patients failed AD and subsequently underwent map-guided ventricular tachycardia (VT) surgery (6 patients) or ICD implantation (14 patients). Of the 6 VT surgery patients, 1 died, 1 had cardiac transplantation, and 1 had an ICD implantation because of persistent inducibility despite the addition of AD. Of the 11 patients who remained on AD as sole therapy, 2 died in the hospital before they could be retested by PES, leaving 9, judged adequately protected by AD alone. Of those, 5 died, and 1 survived recurrent cardiac arrest followed by ICD implantation. In total, 16 conventionally treated patients ended up with late ICD implantation, 3 of whom died. Thus, total mortality in the conventional group was 11 patients (35%): 4 died suddenly, 5 died of heart failure, and 2 died of noncardiac causes. Comparison of the main outcome events in both strategies showed a significant difference in favor of early ICD implantation (hazard ratio, 0.27; 95% CI, 0.09 to 0.85; P = .02). In addition, the early ICD group underwent fewer invasive procedures (median, 1 versus 3; P < .0001), had less therapy changes (P < .0001), and spent fewer days in hospital (median, 34 versus 49; P = .02). CONCLUSIONS: These data suggest that ICD implantation as first choice is preferable to the conventional approach in survivors of cardiac arrest caused by old myocardial infarction. Conventionally treated patients are likely to end up with an ICD, and those who remain on AD as sole therapy have a high risk of death regardless of efficacy assessment, including PES.

Anti-Arrhythmia Agents↗