[Characteristics and prognosis of ventricular tachycardia induced by atrial fibrillation]

The aim of this study was to evaluate the clinical significance of ventricular tachycardia (VT) induced by atrial pacing. A group of 145 patients with spontaneous and induced VT was studied. Twenty-four VTs were induced by atrial stimulation (Group I) and 121 by ventricular stimulation (Group II). The underlying cardiac disease was comparable in the two groups (ejection fraction 32 +/- 14% versus 34 +/- 17%). Spontaneous bi-tachycardias, syncope and VT induced by exercise testing were more common in Group I. The prognosis was worse with 7 cardiac deaths in Group I versus 23 in Group II; recurrences of VT were commoner in group I. In this group, an electrophysiological (branch to branch or fascicular reentry) or clinical mechanism (ischaemia or poor haemodynamic status) could usually be demonstrated. Some cases of idiopathic VT were also observed in young patients. These results suggest that atrial stimulation should be performed routinely during electrophysiological studies of VT because the induction of VT by this method is not uncommon (16%). In addition, these cases of VT usually have a precise mechanism and a poor prognosis and, therefore, an appropriate treatment should be given.

[Bi-tachycardia and ischemic cardiopathy (following myocardial infarction)]

OBJECTIVE

The association of supraventricular tachycardia (SVT) and ventricular tachycardia (VT) is not common. The aim of this study was to evaluate its incidence and possible predisposing factors in patients with a history of myocardial infarction (MI), in order to correct them.

METHODS

Out of 359 patients consecutively recruited for spontaneous VT occurring at least one month after the acute phase of an MI, 33 were noted to have a possible association of SVT with VT. These patients underwent the following investigations: Holter recording, left ventricular ejection fraction (LVEF) measurement, and electrophysiological studies including programmed atrial and ventricular pacing.

RESULTS

The LEVF was 37.5+/-11%. An SVT was induced in 21 patients and a VT in 31 patients. Following investigation, the presumed factor predisposing to the two tachycardias was considered to be initiation of an SVT associated with rapid nodal conduction to the ventricle (Wenckebach point 210+/-23/mn) in 12 patients, branch to branch re-entry in 4 patients, reversible rhythmic dilated cardiomyopathy in 4 patients, an ischemic factor in 8 patients, post-operative period in 1 subject, infundibular VT in 1 subject, and an undetermined mechanism in 3 patients. The specific treatment of each of the identified etiologies usually prevented the recurrence of VT with the exception of one patient who had further VT during defibrillator recording, independent of any SVT.

CONCLUSION

The association of SVT with VT is rare because it was only noted in 9% of subjects who presented with spontaneous VT following myocardial infarction; This incidence is debatable, and could be an underestimate due to the fact that diagnosis is difficult. Several presumed predisposing factors are implicated and should be actively sought.

[Evaluation of prognosis after Q wave myocardial infarction. Comparison of invasive and noninvasive diagnostic strategies]

The predictive value of several diagnostic strategies after myocardial infarction was assessed in 178 patients (mean age 55 +/- 9 years) treated medically after a primary Q wave myocardial infarction. Within 6 weeks of onset of symptoms the authors performed exercise stress test coupled with Thallium 201 scintigraphy, isotopic left ventriculography and conventional coronary angiography with ventriculography. The average left ventricular ejection fraction was 45 +/- 12%. Two non-invasive diagnostic strategies with and without results of scintigraphy and two invasive strategies with and without ventricular volumes were studied. The average follow-up period was 58 +/- 22 months. Sixteen cardiac deaths occurred. Multivariate Cox analysis showed that, in contrast to left ventricular volumes, coronary angiography did not provide additional prognostic value compared with the non-invasive model with Thallium scintigraphy and did not appear to be essential in terms of predictive value in this population. Moreover, the size of reversible defect on Thallium scintigraphy was an independent predictive factor of cardiac death and provided additional and independent prognostic information in the non-invasive and invasive strategies. Therefore, the reduction of residual ischaemia by coronary revascularisation could improve the long-term prognosis after myocardial infarction.

[Does syncope change the results of programmed ventricular stimulation in patients with previous myocardial infarction?]

The induction of a ventricular tachycardia (VT) after myocardial infarction (MI) is associated with a high risk of VT and sudden death (SD) in asymptomatic patients; the purpose of the study was to know if syncope modifies the results of programmed ventricular stimulation (PVS) and the clinical consequences.

METHODS

PVS using two and three extra stimuli delivered in two sites of right ventricle was performed in 1057 patients without spontaneous VT or resuscitated SD at least 1 month after an acute MI; 836 patients (group I) were asymptomatic and were studied for a low ejection fraction or nonsustained VT on Holter monitoring or late potentials; 228 patients (group II) were studied for unexplained syncope. The patients were followed up to 5 years of heart transplantation.

RESULTS

Sustained monomorphic VT (< 280 b/min) was induced in 238 group I patients (28%) and 62 group II patients (29%); ventricular flutter (VT > 270 b/min) or ventricular fibrillation (VF) was induced in 245 group I patients (29%) and 42 group II patients (18%) (P < 0.05); PVS was negative in 353 group I patients (42%) and 124 (55%) group II patients (NS). The patients differ by their prognosis; cardiac mortality was 13% in group I patients and 34% in group II patients with inducible VT < 280 b/min (P < 0.01), 4% in group I patients and 13% in group II patients with inducible VF (P < 0.05), 5% in group I patients and 7% in group II patients with negative study (NS). In conclusion, syncope did not change the results of programmed ventricular stimulation after myocardial infarction. However, syncope increased significantly cardiac mortality of patients with inducible ventricular tachycardia, flutter or fibrillation.

[Correlation of the results of high-amplification ECG and the cycle of induced ventricular tachycardia. Prognostic value]

Analysis of high amplification ECG results as a function of the results of programmed ventricular stimulation on the fate of 240 patients provides the following data: when programmed ventricular stimulation is negative, there are no late potentials since sudden cardiac death is probably due not to a disturbance in primary rhythm but to a disturbance in ischaemic rhythm; in the case of sustained ventricular tachycardia, cardiac mortality is highest (16 per cent) when due to sudden cardiac death or ventricular tachycardia and late potentials are usually present (14 times out of 15); ventricular fibrillation or flutter are accompanied by appreciable cardiac mortality (between 10 and 13 per cent), basically due to sudden cardiac death and, in this case, there are no late potentials. It is possible to observe late potentials which induce ventricular flutter in subjects during programmed stimulation and this might be a risk factor in the subsequent development of ventricular tachycardia.

[Results of programmed ventricular stimulation in induced non-sustained polymorphic ventricular tachycardia and maintenance of stimulation]

Programmed ventricular stimulation risks inducing non-pathological ventricular fibrillo-flutter. The aim of this study was to determine if the induction of a non-sustained polymorphic ventricular tachycardia (over 5 intraventricular reentries) could prevent this incident. One hundred and thirty-three non-sustained polymorphic tachycardias were induced by 2 or 3 extrastimuli during 1450 programmed ventricular stimulation studies. Ventricular stimulation was continued and led to ventricular fibrillo-flutter in 46 cases (Group I); to induction of sustained ventricular tachycardia in 26 cases (Group II) or to no other arrhythmias excepting the non-sustained tachycardia in 61 cases (Group III). The duration of the salvo was similar in all 3 groups. The rate of the induced arrhythmia was significantly lower in Group II (234 vs 290/min). The essential difference between the three groups was the clinical context. Only patients in Group II had previously documented sustained ventricular tachycardia and only patients in Group III had no apparent underlying cardiac disease. These results suggest that the decision to stop programmed ventricular stimulation should be based on the clinical indications of the study. In patients with previously documented or probable sustained ventricular tachycardia, it would seem to be necessary to continue ventricular stimulation irrespective to the rate and duration of the induced non-sustained ventricular tachycardia.

[Prognostic value of ventricular tachycardia induced by stimulation in patients without documented tachycardia]

In order to determine the cause of syncopes or disorders of conduction, 584 programmed stimulations using 2 ventricular extrastimuli delivered during an imposed rhythm were performed, between 1981 and 1985, in patients without ventricular tachycardia (VT) proven by Holter recordings. Eighty-seven non-sustained VT (NSVT) (15%), 8 ventricular fibrillations (VF) (1%), 16 ventricular flutters (VF1) (3%) and 23 sustained VT (SVT) (4%) were induced. To appraise the significance of these responses the patients were followed up for a mean period of 2 +/- 1 years. Among the NSVT patients the first 47 were followed up until 1984 and the others, less numerous, until 1985. Patients who responded to stimulation with NSVT had (4.4%) or did not have an underlying cardiopathy; their mean left ventricular ejection fraction (LVEF) was 53.5 +/- 17% (n = 10); 17% died of heart disease, but the disease was related to VT in only one case; 36% of these patients had cardiac symptoms, but only one presented with episodes of NSVT. Patients who responded with VF had a normal (50%) or abnormal heart; their mean LVEF was 52 +/- 19%; one died of heart failure, the others were asymptomatic. All but one of the patients who responded with VF1 had an underlying cardiopathy and a mean LVEF of 38 +/- 19%; 3 died, 2 of heart failure and 1 of sudden death; 13 were asymptomatic. All patients who responded with SVT had an underlying cardiopathy and a mean LVEF of 37 +/- 13%; 7 (30%) died, including 2 sudden deaths; 2 had episodes of VT and 12 were asymptomatic. In summary, an underlying cardiopathy was present in one-half of the patients who responded with NSVT or VF and in all patients who responded with VF1 or SVT. The risk of VT was low (5%) in patients who responded with NSVT, VF or VF1 and was higher (17%) in those who responded with SVT.

[Paroxysmal atrial fibrillation: main cause of syncope in hypertrophic cardiomyopathy]

The aim of this retrospective study was to determine the mechanism of syncope in idiopathic hypertrophic cardiomyopathy (HCM). An electrocardiographic study was undertaken in 43 patients with HCM: 27 (Group I) had a history of syncope and 16 (Group II) had no history of syncope but were investigated for conduction defects (n = 7) or unsustained ventricular tachycardia (VT) (n = 9). The stimulation protocol used programmed atrial pacing with 1 and 2 extrastimuli and ventricular pacing using up to 3 extrastimuli delivered at 2 sites. The following results were obtained: sustained atrial fibrillation (AF) (> 1 min) was induced in 21 patients in Group I (78%), 4 in Group II (25%); VT was induced in 3 patients in Group I (11%), and 3 in Group II (19%); infra-Hisian block was detected in 1 patient in Group I. The mechanism of syncope was elucidated in 23 patients in Group I (85%): one atrioventricular block 1 sinus node dysfunction, 18 atrial fibrillations, 2 associations of AF-VT and 1 VT. The authors conclude that the prevalence of inducible AF was higher in patients with HCA and syncope than in controls and HCM without syncope: this was the only detectable difference in 67% of patients with unexplained syncope. Paroxysmal AF could therefore explain malaise or syncope in up to 2/3 of cases of HCM.

[Incidence and prognosis of atrioventricular block induced by radiofrequency ablation of intranodal reentrant tachycardia. A multicenter study]

The object of this study was to assess the incidence and significance of atrioventricular block (AVB) induced by radiofrequency ablation of intranodal reentrant tachycardias. The study population was 18 patients aged 44 to 83, selected from a total population of 144 patients treated for recurrent, refractory tachycardias. These patients developed complete AVB (9 cases), 2nd degree ABV (3 cases) and 1st degree AVB (6 cases) either immediately or in the chronic phase after radiofrequency ablation. The outcomes were as follows: 1. In the 9 patients with complete AVB, the block regressed in a period ranging from 7 seconds to 5 minutes. It recurred as complete AVB 1 to 4 days later in 2 patients, and regressed again after a maximum of 10 days. One 47 year old woman had definitive complete AVB; 2. In the 3 patients with 2nd degree AVB, the block regressed within 7 days; 3. In the 6 cases of 1st degree AVB, 2 patients developed transient complete AVB the following day. The possible causes of AVB were: increased vagal tone in 1 case, ablation of the rapid pathway located in a postero-septal site in 8 cases and, in the remainder, pre-existing conduction defects. The authors conclude that transient complete AVB is common and usually has a good prognosis. Definitive complete AVB is a rare but possible (0.7%) complication of radiofrequency ablation of reentrant intranodal tachycardias; other forms of AVB generally regress quickly and, although they may recur within days, they carry a good prognosis in the following months. However, long-term follow-up remains necessary.

[Treatment with lepirudin in heparin-induced thrombocytopenia. A case report]

We report the case of a 71 old woman presenting a bilateral massive pulmonary embolism with intraventricular right thrombus complicating heparin induced thrombocytopenia (HIT) persistent after one month of conventional anticoagulant processing. We underline the effectiveness of lepirudin (Refludan) in the curative processing of pulmonary embolism allowing here to avoid a complex surgical thromboembolectomy. We evoke the place of this molecule in the curative therapeutic strategy of HIT with thrombotic phenomena.

[Alteration of sinus variability after cardiac surgery]

Sinus tachycardia is frequent after cardiac surgery and this tachycardia is probably due to changes of the autonomic nervous system. The objective of this study was to evaluate the changes possibly induced by cardiac surgery, by studying sinus variability (SV) during a 24-hour Holter monitoring. The examination was performed in 28 patients who had undergone cardiac surgery 1 to 6 weeks previously. These patients had no alteration of left ventricular function, or any causes likely to modify SV and they had a normal postoperative course. Their results were compared to those of 4 subjects developing a postoperative complication (1 case of ventricular tachycardia and 3 cases of resuscitated cardiac arrest). The results were also compared to those of 24 age-matched adult controls without heart disease (control group). The study of SV included temporal and spectral analysis of SV with measurement of the standard deviation of normal RR intervals (SD), mean heart rate (HR), percentage of RR intervals differing by more than 50 m/sec from the adjacent interval (pNN50), coefficient of variability (CV) (SD/RR), square root of the differences between successive RR (rMSSD), spectral properties of low frequencies (LF) and high frequencies (HF) and the fractionated spectral property (LF/HF).

RESULTS

(see tables, page 151 and 152). An alteration of SV was therefore observed in the surgical group, and lasted 4 to 6 months after surgery. No difference was observed between subjects without cardiac events and those presenting a cardiac event.

IN CONCLUSION

cardiac surgery decreases all parameters of SV during the first few postoperative months. Certain unexpected cardiac accidents during this period could be explained by these changes.