The signal-averaged electrocardiogram and ventricular arrhythmias after thrombolysis for acute myocardial infarction.

The prevalence of an abnormal signal-averaged electrocardiogram (ECG) and ventricular arrhythmias on 24 h ambulatory electrocardiography was evaluated in 118 patients 13 +/- 2 days after acute myocardial infarction. Group 1 (46 patients) underwent intravenous thrombolysis within 6 h of the onset of symptoms, whereas Group 2 (72 patients) did not. An abnormal signal-averaged ECG was seen in 15% of patients in Group 1 and 21% of those in Group 2 (difference not significant). The number of ventricular premature complexes/h was lower in Group 1 than in Group 2: 2.58 +/- 1.63 versus 7.91 +/- 10.75 (p less than 0.01). However, complex arrhythmias (greater than or equal to 10 ventricular premature complexes/h or ventricular tachycardia) were equally common in Groups 1 and 2 (20% versus 22%, respectively). Their prevalence was similar in patients with or without an abnormal signal-averaged ECG (29% versus 18%, respectively, in Group 1 and 27% versus 21%, respectively, in Group 2). Comparison between patients with (n = 26) or without (n = 20) angiographic patency of the infarct-related coronary artery after thrombolysis showed no significant difference in the prevalence of an abnormal signal-averaged ECG (8% versus 25%, respectively) and complex ventricular arrhythmias (19% versus 20%, respectively). These data suggest that thrombolysis does not affect the prevalence of complex ventricular arrhythmias and an abnormal signal-averaged ECG or their relation after acute myocardial infarction.

Prevalence, time course and malignancy of ventricular arrhythmia during spontaneous ischemic ST-segment depression.

Ventricular arrhythmias during transient myocardial ischemia were studied in 60 patients with spontaneous angina and greater than or equal to 1 ischemic attack with ST-segment depression during 24-hour ambulatory electrocardiography. The patients were divided into 2 groups: group 1, 10 patients (17%) who developed ventricular arrhythmias during 26 of 92 (28%) ischemic attacks; and group 2, 50 patients who did not show this phenomenon. Daily ischemic attacks, total ischemic time and the proportion of symptomatic ischemic attacks were significantly greater (p less than 0.01) in group 1 versus group 2. In group 1 patients, ischemic attacks were found to have twice the duration in the presence of arrhythmias than in their absence (20.4 +/- 11.9 vs 9.1 +/- 8.4 minutes, p less than 0.01); arrhythmias were more common during symptomatic than during silent ischemic attacks (39 vs 13%, p less than 0.02). Arrhythmias occurred at the onset or peak of ST-segment depression (ischemia phase) in 6 cases (60%), during the resolution of ST-segment depression (recovery phase) in 2 cases (20%) and during both phases of ischemic attacks in the remaining 2 (20%). When compared to recovery phase arrhythmias, ischemia phase arrhythmias were characterized by a later onset time (173 +/- 144 vs 58 +/- 54 seconds, p less than 0.01) and a longer duration (105 +/- 107 vs 41 +/- 22 seconds, p less than 0.01). During the ischemia phase, 16 of 353 ventricular premature complexes initiated ventricular tachycardia, while during the recovery phase only 1 of 161 ventricular premature complexes resulted in ventricular tachycardia (4.5 vs 0.6%, p less than 0.02). Thus, ventricular arrhythmias may accompany spontaneous ischemic ST-segment depression, when the latter is recurrent, prolonged and symptomatic; arrhythmias are characterized by a greater frequency, duration and malignancy during the ischemia phase than during the recovery phase of ischemic attacks.

Spontaneous myocardial ischemia and the signal-averaged electrocardiogram.

The effects of transient myocardial ischemia on the signal-averaged electrocardiogram were investigated in 13 patients with coronary artery disease and spontaneous angina undergoing 3-channel ambulatory electrocardiography. Ischemia was seen as ST elevation in 2 patients or ST depression in 11; it was anterior in 5 patients, inferior in 4 and undefined in 4. Signal-averaged electrocardiograms with noise levels less than or equal to 1 microV were obtained from Holter tapes during 54 of 61 ischemic attacks recorded in the study group (88%), and compared with 54 tracings recorded within 60 minutes of the index attacks. Baseline tracings were normal in 8 patients (62%), showed a long QRS duration in 2 (15%), and both a long QRS duration and a late potential in the remaining 3 (23%). Comparison of recordings at baseline and during ischemic attacks revealed no significant changes in signal-averaged electrocardiographic parameters. Absence of significant differences was also noted when analysis was performed according to the type of ischemic attacks (associated with ST elevation [n = 14] or ST depression [n = 40]), their location (anterior [n = 21] or inferior [n = 23]), their duration (greater than 10 minutes [n = 29] or less than or equal to 10 minutes [n = 25]), and their magnitude (greater than 2 mm [n = 18] or less than or equal to 2 mm [n = 36]). It is concluded that spontaneous transient myocardial ischemia, independent of its type, location, duration and magnitude, does not generate a substrate for late potentials on the signal-averaged electrocardiogram.

Lack of correlation between transient myocardial ischemia and late potentials on the signal-averaged electrocardiogram.

The relation between transient myocardial ischemia and late potentials was investigated in 100 patients with coronary artery disease who underwent serial recordings of the signal-averaged electrocardiogram before, during and after dipyridamole infusion. During this test, 47 patients (group 1) developed transient myocardial ischemia (with ST elevation in 14 cases and ST depression in 33), whereas 53 patients (group 2) did not. Baseline signal-averaged electrocardiogram was abnormal in 20 patients (20%): a QRS duration greater than 115 ms was seen in 6 patients, a late potential (root mean square voltage of last 40 ms of QRS [RMS40] less than 25 microV) in 9, both abnormalities in 5, with no significant differences between groups 1 and 2 (26 vs 15%, respectively). In both groups, comparison of recordings obtained before, during and after dipyridamole test revealed no significant changes in QRS duration and RMS40. Absence of significant differences was also observed when patients with transient ischemic ST elevation or ST depression were examined separately. During the test, 100% of abnormal basal recordings remained abnormal and 98% of normal recordings remained within normal limits. In only 2 patients (from group 1) RMS40, which showed borderline values at baseline, decreased to abnormal values during dipyridamole test. These data suggest that electrophysiologic abnormalities induced by transient myocardial ischemia may not bear any relation with the substrate for chronic reentrant ventricular tachyarrhythmias, as reflected by late potentials on the signal-averaged electrocardiogram.

Transient myocardial ischemia detected by Holter monitoring during the early post-infarction period.

BACKGROUND: On the basis of extensive studies concerning the prognostic value of Holter monitoring in patients with angina, we evaluated the clinical outcome of patients with transient ischemic episodes soon after myocardial infarction. METHODS: The incidence and clinical significance of myocardial ischemia, detected in the acute phase of myocardial infarction, were evaluated in 87 patients. Twenty-four-hour Holter recordings were obtained on the 2nd, 4th, 6th, and 12th hospital day. RESULTS: Myocardial ischemia was detected during at least one of the four recording periods in 28 patients (32%). A total of 157 ischemic episodes were documented. The proportion of recordings that showed transient myocardial ischemia progressively declined from 20% on the 2nd day to 5% on the 12th post-infarction day. Of the 157 ischemic episodes, 132 (84%) were silent and 25 (16%) were symptomatic. Transient ST-segment elevation was present in 99 of the 157 episodes (63%), while transient ST-segment depression occurred in the remaining 58 of the 157 cases (37%). One or more in-hospital cardiac events (reinfarction, acute pulmonary edema, ventricular tachycardia or fibrillation, cardiac death) were more frequent in patients with (group I) than in those without (group II) transient myocardial ischemia [nine out of 28 (32%) versus six out of 59 (10%); P < 0.03]. At follow-up (mean 11.5 +/- 2 months) the incidence of cardiac events (angina, reinfarction, heart failure, ventricular tachycardia or fibrillation, revascularization procedures, cardiac death, sudden death) was comparable in the two groups [four out of 24 (17%) versus 10 out of 49 (20%); NS]. Predischarge exercise testing, performed in 64 patients (74%), showed myocardial ischemia in 50%; the percentage did not vary significantly between group I and group II patients. Moreover, a positive exercise test was not predictive of major cardiac events at follow-up. CONCLUSION: Transient myocardial ischemia, frequently silent, is not uncommon in the acute phase of myocardial infarction and progressively decreases during the in-hospital stay. Its recognition in the subacute phase of myocardial infarction may lead to the identification of a subset of patients at the highest risk of early major complications, who may benefit from aggressive diagnostic and therapeutic strategies.

Combined cardiac cinefluoroscopy, exercise testing and ambulatory ST-segment monitoring in the diagnosis of coronary artery disease; a report of 104 symptomatic patients.

To enhance diagnostic accuracy in coronary artery disease, cardiac cinefluoroscopy for the detection of coronary artery calcification was combined with exercise test and ambulatory ST-segment monitoring in 104 symptomatic patients before they underwent coronary angiography. In 44 patients with typical angina the combination of the three noninvasive tests and the exercise test alone both detected 92% of subjects with clinically important coronary artery disease. In 60 patients with atypical angina, the combination of the three noninvasive tests screened 77% of the subjects with clinically important coronary artery disease versus 43% after exercise test only (P less than 0.001). The exercise electrocardiogram was false negative in a substantial number of patients with atypical angina due to the presence of a good coronary reserve or to a daily circadian variation in the tone of the coronary arteries. Under these circumstances, cardiac cinefluoroscopy gave additional anatomic information to the physiological assessment of ischemia provided by the exercise test and ambulatory ST-segment monitoring. Our study suggests that the combination of cardiac cinefluoroscopy with other noninvasive tests may be particularly useful in screening atypically symptomatic populations.

[Chronic pericarditis from radiation (author's transl)]. / Pericardite cronica da radiazioni

A case of chronic pericarditis with effusion in a 25 years old white man, 19 months after therapeutic irradiation of the mediastinum with a total dose of 4.350 rads for Hodgkin's disease. Pericardiectomy was followed by improvement of functional capacity persistent 7 months after operation.

[Negative post-ischemic T waves in variant angina]. / La T negativa post-ischemica nell'angina variante.

The clinical and prognostic significance of negative T waves on the basal electrocardiograms of patients with unstable angina has been recently investigated with controversial results. Moreover, there is little data regarding this phenomenon in patients with variant angina. In order to evaluate the significance of negative post-ischemic T waves in patients with variant angina, 72 patients underwent Holter recording and coronary angiography. Negative T waves were present in 38 out of 72 patients (53%): they were anterior in 24 cases and inferior in 14 cases. The negative T-wave phenomenon was present in 29 patients on admission and showed up in 9 patients during hospitalization. Holter recording showed no significant differences between patients with or without negative T waves with regards to: 1) the proportion of symptomatic transient myocardial ischemic attacks; 2) the frequency of arrhythmias during transient myocardial ischemic attacks; 3) the maximum duration of transient myocardial ischemic attacks; 4) the maximum degree of ST elevation during transient myocardial ischemic attacks. Negative T waves on the anterior leads showed a moderate sensitivity (54%) and total predictive accuracy (52%), as well as a lower specificity (43%) and negative predictive accuracy (15%) for a significant stenosis of the left anterior descending coronary artery. This was due to the presence of several patients with left anterior descending artery stenosis and without negative T waves. On the other hand, negative T waves on the inferior leads were characterized by high sensitivity (85%), specificity (80%) and total predictive accuracy (82%) for a significant stenosis of the right coronary artery and/or the circumflex artery.(ABSTRACT TRUNCATED AT 250 WORDS)

[Characterization and therapy of ventricular arrhythmias due to transient myocardial ischemic attacks in variant angina]. / Tipizzazione e terapia delle aritmie ventricolari da attacco ischemico miocardico transitorio nell'angina variante.

Forty-two patients with variant angina were studied by ambulatory ECG monitoring to determine the incidence and the characteristics of ventricular arrhythmias during ischemic attacks. Twenty-six patients had no ventricular arrhythmias in 633 ischemic attacks; 16 patients had ventricular arrhythmias in 116/586 ischemic attacks. The number of ischemic attacks per day and the magnitude of ST elevation were significantly (p less than 0.05) greater in patients with ventricular arrhythmias. Ventricular arrhythmias appeared at the onset or at the peak of ST elevation (first phase) in 17 ischemic attacks, during the resolution of ST elevation (second phase) in 43 attacks, during both the phases in 9 attacks. ST alternans appeared during 6 ischemic attacks with arrhythmias. Two episodes of ventricular fibrillation and 22 runs of ventricular tachycardia occurred during the first phase, 17 episodes of ventricular tachycardia were recorded during the second phase. Ventricular tachycardia of the second phase compared with ventricular tachycardias of the first phase were significantly (p less than 0.01) slower, uniform and initiated by a late premature beat. Incidence of arrhythmias of the second phase was strictly correlated with the duration of ischemic attacks. Nine patients who showed ventricular arrhythmias during the second phase of ischemic attacks were enrolled in a cross-over study to assess the antiarrhythmic effects of nifedipine (120 mg/day) and verapamil (480 mg/day). During treatment with nifedipine, the frequency of ischemic attacks declined by 85%, while the frequency of attacks with arrhythmias declined by 97% (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Combined gallopamil and isosorbide-5-mononitrate in "mixed" angina pectoris.

The efficacy of combining gallopamil and isosorbide-5-mononitrate (IS-5-MN) was evaluated in 15 patients with "mixed" angina and documented coronary artery disease who participated in a 4-week, double-blind, double-dummy, crossover, placebo-controlled trial. After the first week of the placebo phase (single-blinded), all patients received in three different weeks IS-5-MN 20 mg three times daily, gallopamil 50 mg three times daily, and the same dosages of IS-5-MN and gallopamil three times daily. Exercise tolerance, and peak values of heart rate, systolic blood pressure, double product (DP/100), and ST-segment were evaluated with a treadmill test at the end of each phase. The improvement in exercise tolerance obtained by the combination of the two drugs was significantly greater (p < 0.01) than that achieved by IS-5-MN but not that by gallopamil monotherapy (NS). This effect was accompanied by significant (p < 0.05) reduction (-61%) in ST-segment and significant (p < 0.05) increment (+8%) in peak heart rate only after administration of the combination of the two drugs. The number of ST-depression (ST-) > 1 mm or ST-elevation (ST+) episodes on 24-h Holter monitoring lasting > or = 1 min were also noted in all patients at the end of each phase of the trial.(ABSTRACT TRUNCATED AT 250 WORDS)

Value of low-dose echodobutamine in the diagnosis of patency of the infarct related coronary artery.

The resumption of contractility of asynergic segments in survivors after acute myocardial infarction (AMI) may be detected in viable myocardial areas. We have correlated the detection of viable myocardium, assessed with low dose dobutamine testing, with coronary angiography and clinical outcome in 66 consecutive survivors of AMI using the echocardiographic evidence of left ventricular wall motion abnormalities. The test enabled the identification of two groups: group A, comprising 32 patients (pts) demonstrating wall motion recovery at dobutamine infusion and group B, comprising 34 pts without wall motion recovery. The mean basal asynergy score index was 5.8 +/- 4.2 in group A and 6.0 +/- 4.2 in group B (p = ns). With dobutamine testing the score decreased to 2.8 +/- 3.6 in group A (p < 0.001 with respect to basal value), while it did not change significantly in group B. Left ventricular end diastolic volume (ml) was similar in the two groups (114 +/- 35 vs 107 +/- 79, p = NS). The infarct related artery (IRA) patency rate was 87.5% in group A, vs 26.5% in group B (p < 0.001). After a mean follow-up of 11 +/- 5 months, group A pts had basal asynergy score improvement (2.6 +/- 3.1, p < 0.001) and mild left ventricular end diastolic volume (ml) reduction, (108 +/- 32, p = NS), while group B pts had left ventricle end diastolic volume enlargement (130 +/- 38, p < 0.05), without score asynergy modification. Moreover all pts who experienced heart failure at follow-up were in group B.(ABSTRACT TRUNCATED AT 250 WORDS)

[Diagnostic value and safety of dobutamine echocardiography in the diagnosis of coronary disease]. / Valore diagnostico e sicurezza del test eco-dobutamina nella diagnosi di coronaropatia.

To assess the safety and diagnostic value of dobutamine stress-echocardiography (DSE), we studied 109 patients with ischemic heart disease: 78 patients with recent myocardial infarction, 31 patients with chest pain (14 patients without and 17 patients with previous myocardial infarction). Echocardiograms were recorded during dobutamine infusion in 5-minute stages to a maximum dose of 40 mcg/kg/min. The test was considered positive when dobutamine infusion induced a new wall motion abnormality. In 95 pts with recent or previous myocardial infarction new asynergies were classified as being within the infarct zone or outside the infarct zone based on the relation with vascular zones at coronary angiography. All patients underwent exercise stress test (EST) according to the Bruce protocol, and coronary angiography within one week from the test: significant coronary artery disease was defined as > or = 50% diameter stenosis for left main artery and > or = 70% for the other vessels. Five patients (4.6%) had ventricular arrhythmias and 3 patients (2.7%) had systolic blood pressure increase > or = 200 mm Hg in the first stage of DSE, without new wall motion abnormalities, and were excluded from diagnostic value analysis. DSE had a sensitivity of 86% vs 56% of EST (p < 0.001); both had specificity of 94% and positive prognostic value of 98%; diagnostic accuracy of DSE was 87% vs 62% of EST (p < 0.001); negative predictive value was not statistically different. Sensitivity of DSE in single vessel disease (78%) was significantly lower (p < 0.05) than sensitivity in multivessel disease (95%). Sensitivity of DSE in detecting multivessel disease in patients with myocardial infarction was 80% vs 55% of EST (p < 0.05); specificity 96% vs 63% (p < 0.001); diagnostic accuracy 90% vs 60% (p < 0.001); positive predictive value 93% vs 48% (p < 0.001); negative predictive value 89% vs 70% (p < 0.05). At the ischemic threshold, EST caused the achievement of higher heart rate and rate-pressure product; in patients with single vessel disease heart rate was higher than in multivessel disease (141 +/- 19 vs 117 +/- 21, p < 0.001). No differences were detected during DSE in heart rate, blood pressure, rate-pressure product; the dose of dobutamine infused at the ischemic threshold in patients with multivessel disease was significantly lower than in those with single vessel disease (15.2 +/- 5.4 vs 19.4 +/- 6 mcg/kg/min, p < 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)