QT dispersion and early arrhythmic risk during acute myocardial infarction.

BACKGROUND: QT dispersion (maximal minus minimal QT interval calculated on a standard 12-lead electrocardiogram) has been suggested to reflect regional variations of ventricular repolarization and to provide a substrate for reentry ventricular arrhythmias. In this study we evaluate QT dispersion in patients with acute myocardial infarction and assess its relation with early severe ventricular arrhythmias. METHODS AND RESULTS: We studied 101 patients with acute myocardial infarction and a control group of 97 healthy subjects. We determined QT and QTc dispersion on the electrocardiograms performed 12 hours and 3 and 10 days after the onset of symptoms in myocardial infarction patients and on the control group. The average values of QT and QTc dispersion (measured hereafter in milliseconds, ms) were as follows: 70.5 +/- 42.5-87 +/- 46.6 (after 12 hours), 66.5 +/- 37.8-76.9 +/- 43.5 (on day 3), 68.9 +/- 42-76.3 +/- 43.8 (on day 10) and 44 +/- 13.4-54.2 +/- 16.3 (in control group). We observed statistically significant differences in QT and QTc dispersion between the electrocardiogram of normal subjects and each of the three electrocardiograms performed on patients with infarction (p < 0.0005, p < 0.005). We recorded a greater QT dispersion in patients with anterior infarction with respect to those with inferior/lateral infarction (79 +/- 38.6 vs 65.2 +/- 43.16, p < 0.05) and in patients with ejection fraction < 45% (93.1 +/- 28.4 vs 68.3 +/- 34.1 p < 0.005). During the first three days, QT dispersion did not differ in patients treated with thrombolytic agents with respect to those who were untreated, while on day 10 untreated patients showed higher values (74.9 +/- 45.3 vs 60.5 +/- 37.7, p < 0.05). Creatine kinase peak level, sex and age of the patients did not influence QT dispersion. Thirteen patients (12.8%) developed severe ventricular arrhythmias within 72 hours after infarction: 8 patients (7.9%) had ventricular fibrillation and 5 patients (4.9%) had sustained ventricular tachycardia. We found higher early QT and QTc dispersion values in patients who developed severe ventricular arrhythmias (108.8 +/- 63.2 and 125.8 +/- 68.5) with respect to patients who did not (63.3 +/- 32.9 and 80.8 +/- 38.9, p < 0.0005, p < 0.0005). CONCLUSIONS: Our data suggest that QT dispersion: 1) increases during acute myocardial infarction; 2) peaks in the early hours after symptom onset; 3) drops late after infarction in patients treated with thrombolytic agents; 4) is associated with early severe ventricular arrhythmias.

[The role of an electropharmacological transesophageal test in the prevention of paroxysmal atrial fibrillation. Experience with flecainide]. / Ruolo del test elettrofarmacologico transesofageo nella profilassi della fibrillazione atriale parossistica. Esperienza con flecainide.

BACKGROUND: The management of patients with paroxysmal atrial fibrillation (AF) is unsuccessful, because AF recurs in about 50% of patients despite an antiarrhythmic treatment. Usefulness of non-pharmacological strategies is available in a limited subset of patients and it does not present a global solution to the problem. At present, treatment with antiarrhythmic agents is the only available tool in patients with AF recurrence. The aim of this study was to assess the predictive value of the electropharmacological transesophageal (TE) test in the management of patients with paroxysmal AF treated by flecainide. METHODS: In 32 patients, ranging in age from 38 to 70 years (mean: 59 +/- 12 years), with documented episodes of paroxysmal AF (mean: 5.6 +/- 3.7 episodes/last year), we performed an electrophysiological transesophageal (TE) test following pharmacological wash-out. An aggressive protocol was used: step A: 10 sec atrial burst at Wenckebach point + 10 bpm, 200 and 250 bpm; step B: 10 sec atrial bursts at 300, 400, 500 and 600 bpm; step C: 8 sec increasing rate burst from 200 to 800 bpm. Induction of sustained AF (> 1 min) was considered the end-point. Patients were treated with flecainide 100 mg bid and a second TE test was performed at the steady-state, with an identical induction protocol and end-point. Based on the response of the second test, patients were divided into responders (R Group: non-inducible AF) and non-responders (NR Group: inducible, sustained AF). Patients were followed-up by periodical controls and contacted by telephone to confirm their clinical status. RESULTS: Sustained AF was induced in 30 patients (94%) at the first TE study. Eight of them dropped-out at the time of the second TE test (6 patients for lack of consent, 1 patient for side-effects and another one for proarrhythmic effects). In the mean follow-up of 15 +/- 6 months, among patients who underwent a second TE test, AF recurrence was documented in 2 out of 14 patients from the R Group and in 7 out of 10 patients from the NR Group (p < 0.01). There were 4 AF episodes in the R Group and 19 in the NR Group (p < 0.001). We did not find significant statistical differences between the two groups in terms of age, sex, body weight, AF episodes/past year, P-wave duration, left atrial dimension, structural heart disease, AF duration at the first TE test and follow-up duration. In five patients from the NR Group with induced AF lasting > 5 min, the percentage of recurrence was 100% and there were 16 AF episodes. Global percentage of patients with recurrence was 37%. CONCLUSIONS: Flecainide is effective in reducing the incidence of AF and results are similar to other antiarrhythmic agents generally used. The electropharmacological TE test might be a useful tool to predict the response to an antiarrhythmic treatment.

[Idiopathic atrial fibrillation of recent onset and atrial stunning: the echocardiographic evidence after pharmacological cardioversion]. / Fibrillazione atriale idiopatica di recente insorgenza e stunning atriale: evidenza ecocardiografica dopo cardioversione farmacologica.

Successful cardioversion of atrial fibrillation may result in prolonged recovery of normal atrial mechanical function. This prolonged recovery of atrial contraction (so-called atrial stunning) might depend on: the amount of energy delivered during direct current cardioversion; the time course between the onset of atrial fibrillation and the conversion to sinus rhythm; the size of the left atrium; the underlying cardiac disease. The aim of this study was to evaluate, in subjects with normal atrial size and without heart disease, the phenomenon of atrial stunning soon after pharmacological cardioversion of an episode of atrial fibrillation of recent onset. Twenty-five patients with an acute episode of atrial fibrillation, without evidence of heart disease and M-mode left atrial dimension (< or = 40 mm received i.v. propafenone or flecainide 2 mg/kg/10 min in order to restore sinus rhythm. Atrial fibrillation lasted < 48 hours in all patients. Doppler echocardiography was used to assess atrial function, by recording the peak velocity of atrial contraction (A wave). An echocardiographic study was performed within 12 hours of successful cardioversion and was repeated on day 3, 12 and 30. The size of the left atrium (37 +/- 3.9; 37.57 +/- 2.9; 37.4 +/- 4; 37.82 +/- 3.7 mm) and peak E velocity (57.97 +/- 18.3; 59.4 +/- 18.3; 59.0 +/- 16; 59.07 +/- 16.7 cm/s) did not show any significant differences over the time, as demonstrated by the serial echocardiographic evaluations. In contrast, both peak A velocity (cm/s) and E/A ratio evaluated within 12 hours of cardioversion (60.29 +/- 12.3 and 1.0 +/- 0.37) and on day 3 (73.71 +/- 10.7 and 0.82 +/- 0.27) were statistically different (p < 0.000001 and p < 0.00001). No further statistically significant increase was found in subsequent examinations (respectively 76.31 +/- 12 and 0.78 +/- 0.24 on day 12, and 76.91 +/- 14.8 and 0.78 +/- 0.21 on day 30). In conclusion, this study suggests that patients with alone atrial fibrillation of recent onset have a delayed recovery of normal atrial systolic function even after pharmacological cardioversion.

[Mitral valve prolapse. Age and sex incidence, echocardiographic diagnosis and clinical and electrocardiographic correlations]. / Prolasso della mitrale. Incidenza per età e sesso, diagnosi ecocardiografica e correlazioni cliniche ed elettrocardiografiche.

The paper reports an electrocardiographic and M and B-mode echocardiographical study in 3682 non-selected patients among which a total of 241 were identified with mitral valve prolapse. In males the highest frequency was found during the second decade of life with a tendency to decrease with increasing age. In females, who were found to be the most severely affected (2:1 in relation to males), two peaks of incidence were observed during the third and fifth decade, with a greater frequency in the latter and a marked absence of cases in the fourth decade. Many echocardiographically diagnosed mitral prolapses were both clinically and electrocardiographically silent; moreover it was observed that the risks of this complication increased in parallel to the thinness and redundance of the mitralic flap affected by prolapse and the dilation of the valvular ring.