Ventricular and supraventricular arrhythmias in clinically silent right ventricular infarction.

To study the relationship between clinically silent right ventricular infarction and the incidence of a-v block, atrial and ventricular arrhythmias, 100 patients with inferior wall myocardial infarction underwent equilibrium gated radioisotopic angiocardiography. Fifty-four of them had radioisotopic evidence of right ventricular involvement and 43 (80%) of them had a-v block and/or supraventricular arrhythmias during the acute phase of the infarct, while only 10 (22%) of the 46 patients without right ventricular involvement did. As regards the incidence of ventricular tachyarrhythmias, 14 (26%) patients with right ventricular involvement had ventricular tachycardia and/or fibrillation, while only one patient without right ventricular involvement had ventricular tachycardia, and no patients had ventricular fibrillation. Moreover, V4R-precordial lead showed a sensitivity in predicting the risk of developing a-v block/supraventricular arrhythmias and ventricular tachyarrhythmias of 0.84 and 0.79, respectively. Therefore, right ventricular involvement should be suspected when atrial arrhythmias, a-v block and ventricular tachyarrhythmias are found in early acute inferior wall myocardial infarction. On the other hand, when right precordial lead V4R in early acute inferior infarction shows ST-elevation and/or a QS pattern, the sudden occurrence of these arrhythmias should be suspected, and possibly prevented.

Effects of infusion of glucose-insulin-potassium on myocardial function after a recent myocardial infarction.

UNLABELLED: We studied the effects of glucose, insulin, and KCl infusion (GIK), on regional myocardial perfusion and function by 99m-Tc-tetrofosmin-gated SPECT. METHODS: We studied 21 male patients with their first uncomplicated acute myocardial infarction (AMI). All patients underwent a rest and submaximal stress before and after 24-hour infusion of GIK-solution (group A) or saline solution (group B). RESULTS: Group A showed better stress tolerance and ischaemic threshold improvement after GIK infusion whilst no statistical differences were found between basal and post-infusion test in group B. At first the stress test in group A, of the 192 segments analysed, 52 (27%) showed reversible perfusion defect. In group B, of 144 segments analysed, 31 (21%) showed reversible perfusion defect. A post-infusion analysis in group A showed a post-GIK end-diastolic significant count improvement in 21 segments, and a post-GIK end-systolic count improvement in 22 segments. In group B, perfusion increase was observed only in 4 segments, whilst systolic thickening increase was observed only in 1 segment. CONCLUSION: These data demonstrate the efficacy of GIK infusion to improve regional myocardial perfusion and function mainly in segments adjacent to the recently infarcted area.

[The autonomic nervous system in myocardial infarction]. / Il sistema nervoso autonomo nell'infarto miocardico.

The occurrence of alterations in the autonomic control of cardiovascular function has long been known. Nevertheless, only in the last 15 years with the development and utilization of techniques such as heart rate variability and baroreflex analysis, unforeseeable amounts of information have been collected. The appraisal of alterations in the autonomic control mechanisms in the acute and post-acute phase of myocardial infarction has not only confirmed the presence of an increased sympathetic and of a reduced vagal modulation in most of post-myocardial infarction patients. It has also allowed the clinically relevant identification of those patients with an increased arrhythmic and total cardiac mortality. Most the high-risk patients are indeed characterized by a marked reduction in heart rate variability that can be detected using different methodologies. For example, with time-domain analysis of heart rate variability, it has been shown that an SDNN < 70 ms identifies patients at risk. By using spectral analysis, it has been possible to realize that the loss or marked attenuation of those rhythmical components that reflect autonomic modulation is also a characteristic of the high-risk patients. A decreased responsiveness of the sinus node to autonomic inputs may also explain the reduction in baroreflex sensitivity that characterizes patients with an increased arrhythmic mortality. In conclusion, the appraisal in each patient of the extent of the alterations in the autonomic control mechanism is nowadays a critical component of the clinical assessment not only for risk stratification but also in order to guide the prescription of new pharmacological and non-pharmacological therapies.

Prognostic significance and evolution of late ventricular potentials in the first year after myocardial infarction: a prospective study.

We performed a prospective study of the high-frequency components of the terminal portion of the QRS complex in 220 patients who survived acute myocardial infarction. Signal-averaged electrocardiograms (SA-ECGs) were performed before hospital discharge (16 +/- 6 days) and then serially at regular intervals over the following year. SA-ECGs were processed using a 40 Hz high-pass bidirectional filter. Duration of "filtered" QRS (D-normal value less than 120 ms), duration of the low-amplitude signals (D40 - n.v. less than 39 ms) and last 40 ms voltage of the QRS complex (V40 - n.v. greater than 20 microV) were measured. Late potentials (LPs) were defined as the presence of two or more abnormal values. In addition, 24-hour Holter monitoring was performed in 208 patients and left ventricular ejection fraction (LVEF) was determined by scintigraphy in 111. Sixty-two patients (group 1) had LPs, 158 had normal SA-ECGs (group 2). Spontaneous normalization of SA-ECGs occurred in 20% of patients after 6 months, although the mean values of D, D40 and V40 did not change significantly and the reproducibility was very good for all the indexes during all the follow-up controls. Three patients had sudden death and three presented again with spontaneous, sustained ventricular tachycardia. Five of 62 (8%) group 1 patients had an arrhythmic event compared with one of 158 patients (0.6%) in group 2. The sensitivity of SA-ECGs as a predictor of arrhythmic events was 83% with a specificity of 73%. Patients with subsequent arrhythmic events had longer filtered QRS (133 +/- 19 vs 104 +/- 16 ms; P less than 0.001), longer duration of the low-amplitude signals (54 +/- 15 vs 33 +/- 14 ms; P less than 0.01), and lower voltages in the last 40 ms of the filtered QRS (11 +/- 3 vs 36 +/- 25 microV; P less than 0.02) and, moreover, higher peak CK values and lower LVEF than those without such events. In conclusion, SA-ECGs provide important prognostic information in identifying patients at risk of arrhythmic events after myocardial infarction although dynamic changes of LPs are observed during the first year after myocardial infarction.

[Late ventricular potentials in the post-infarct patient. A follow-up at 4 years]. / I potenziali tardivi ventricolari nel post-infarto. Follow-up a 4 anni.

We performed a prospective study to evaluate the prognostic significance and the natural history of late ventricular potentials (LPs) in 209 patients (165 males and 44 females; mean age 59.8 +/- 10 years) who survived acute myocardial infarction. Signal-averaged electrocardiograms (SA-ECGs) were performed before hospital discharge (16 +/- 5 days) and after four years (mean follow-up 42 +/- 7 months). SA-ECGs were processed using a 40 Hz high-pass bidirectional filter. Duration of "filtered" QRS (normal value < 120 msec), duration of the low-amplitude signals (n.v. < 39 msec) and last 40 msec voltage of the QRS complex (n.v. > 20 microV) were measured. LPs were defined as the presence of two or more abnormal values. In addition, 24-hour Holter monitoring was performed in all patients, and left ventricular ejection fraction (LVEF) was determined by scintigraphy in 120 (57.4%). Sixty patients (28.7%) had LPs before hospital discharge (group 1), and 149 (71.3%) had normal SA-ECGs (group 2). During the follow-up period there were 10 arrhythmic events, 7 of which were sudden deaths, and three cases of sustained ventricular tachycardia. SA-ECG was repeated in 141 patients (68%). The mean values of SA-ECG's parameters did not change significantly between the two controls, and the correlation was good for all of them. Despite this, spontaneous normalization of SA-ECGs occurred in 21 patients (60%) and the subsequent appearance of LPs was seen in 13 (12%); in these latter, the SA-ECG's parameters measured before hospital discharge were "borderline" and significantly different from those who did not change. The sensitivity of SA-ECG as a predictor of arrhythmic events was 80% and the specificity 74%. Patients with arrhythmic events had a longer filtered QRS (126 +/- 33 vs 103 +/- 12 msec; p < 0.001), longer duration of the low-amplitude signals (57 +/- 23 vs 32 +/- 11 msec; p < 0.001), lower voltages (17 +/- 8 vs 36 +/- 24 microV; p < 0.001), and, moreover, higher peak CK values, lower LVEF and higher value of Lown modified class. In conclusion, SA-ECG confirms its value in identifying patients at risk of arrhythmic events after myocardial infarction. SA-ECG recordings taken before the discharge can be used to predict serial changes during follow-up.

Non-pulmonary effects induced by the addition of formoterol to budesonide therapy in patients with mild or moderate persistent asthma.

OBJECTIVE: The present study was designed to assess the non-pulmonary effects of a 2-week treatment with the addition of formoterol to budesonide therapy in 10 patients with mild or moderate asthma. METHODS: Each patient was invited to perform a screening visit which included spirometry before and after inhalation of 12 microg formoterol with a metered dose inhaler (MDI), measurement of arterial blood pressure, baseline electrocardiography and 24-hour Holter monitoring, and a test for evaluating upper limb tremor. Patients then began bronchodilating therapy with 12 microg formoterol MDI and 400 microg budesonide Turbuhaler b.i.d. Each patient was also given a peak flowmeter and a diary in which he had to record the morning and evening values measured before taking inhaled drugs. Two weeks later, the patients repeated the same examinations; the diary card was returned 2 months after the beginning of the study. RESULTS: Adding formoterol to budesonide therapy caused a significant improvement in lung function, but neither induced any statistically significant effect on mean heart rate, nor altered the circadian rhythm of autonomic regulation nor elicited significant alterations in cardiac morphology. However, the evaluation of upper limb tremor revealed a statistically significant increase (p = 0.02). CONCLUSIONS: This study shows that adding the recommended dose of formoterol to an inhaled corticosteroid therapy does not induce significant cardiac undesirable effects, although tremor, surely due to stimulation of beta(2) receptors of the skeletal muscles, may sometimes be a limiting effect.

[A comparison between attenuation-corrected and -uncorrected transmission-emission SPECT images obtained with Tl-201 in CAD patients]. / Confronto tra immagini SPECT trasmissive-emissive corrette per attenuazione e non corrette, ottenute con Tl-201 in coronaropatici.

BACKGROUND: The aim of this study was to evaluate the impact of attenuation correction (AC) on the diagnostic accuracy of conventional stress/red thallium SPECT studies. METHODS: We studied 60 consecutive patients (36 males) who underwent conventional diagnostic stress/red study with and without AC (NAC) using a dual-head SPECT camera (Vertex ADAC) with a 153Gd source. The mean age of these patients was 60 years (30-80) and 29 of the subjects had a history of MI. Reconstructed images were visually analyzed using 20 segments scored on a 5-point scale (0 = normal, 4 = no uptake). Diagnostic accuracy was evaluated in 24 consecutive patients who underwent coronary angiography. Polar plots from each of the four reconstructed data sets per patient were normalized on the maximum and quantified using a nine segment model. RESULTS: The comparison between the segmental stress score obtained with and without AC showed agreement in 1057 out of 1200 (88%) segments analyzed, K statistic value = 0.67. The number of fixed defects was significantly lower after AC. The diagnostic accuracy, evaluated in 24 patients (480 segs), was not significantly different between AC and NAC analysis (80 vs 84% respectively). CONCLUSIONS: AC seems to reduce the number of fixed defects due to attenuation artefacts without improving diagnostic accuracy, probably because of the low number of subjects submitted to angiography and of the interpreting bias due to the expertise of the operators. In fact, in the rather small group of patients evaluated, no improvement in diagnostic accuracy was observed, probably because several attenuation defects were not considered pathological due to operator expertise.

[Myocardial scintigraphy by the gated SPECT method in coronary disease patients with postischemic stunning]. / Scintigrafia miocardica con metodica gated SPECT in coronaropatici con stordimento post-ischemico.

UNLABELLED: Gated SPECT using Tc-99m-labeled flow tracers provides simultaneous assessment of global and regional myocardial perfusion and function. The aim of this study was to evaluate whether regional wall thickening (WT) obtained after stress and at rest makes it possible to identify and analyze a subgroup of post-ischemic stunned patients. METHODS: We studied 20 patients (18 males) who underwent conventional diagnostic dual-day stress/rest Gated SPECT following injection of 925 MBq of 99mTc-tetrofosmin using a dual-head SPECT camera (Vertex ADAC). The mean age of these patients was 59 years (38-71) and 10 of them had a history of previous acute myocardial infarction (AMI). Perfusion was analyzed on ungated images using 20 segments scored on a 5-point scale (0 = normal, 4 = no uptake), while WT and motion were assessed visually on stress/rest end-systolic images using a 4-point score (0 = normal, 3 = absence of WT/motion). Left ventricular ejection fraction (LVEF) and volumes were calculated. All patients underwent coronary angiography. RESULTS: All patients showed at least one reversible defect with post-stress WT reduction and normal rest WT. The stunned group showed a significant post-stress reduction of LVEF and a statistically non-significant increase of end systolic volume (ESV). A good correlation was observed between global perfusion and WT score both at stress and rest conditions; LVEF showed a significant inverse correlation with global post-stress and rest perfusion and WT score. ESV and the global perfusion stress/rest score showed a good correlation, while end-diastolic volume did not correlate. In 44% of the segments with fixed defects, there was a normal WT and normal coronary-related vessel (false positives); 28% of reversible segments showed a post-stress pathological WT and five of them a rest pathological WT. CONCLUSIONS: The gated SPECT myocardial perfusion evaluation allowed us to analyze a subgroup of post-stress stunned coronary artery disease patients. The post-stress LVEF reduction in this population seems to be due to the increase of end-systolic volume caused by endocardial ischemia. The stunned segments showed severe perfusion defects.