F. Cobelli

Left Atrial Appendage Dysfunction: A Cause of Thrombosis? Evidence by Transesophageal Echocardiography-Doppler Studies

The blood flow velocity patterns within the left atrial appendage were studied by transesophageal color flow imaging and pulsed Doppler in 84 patients. At the time of the study, 57 of the patients were in sinus rhythm, 25 were in atrial fibrillation, and two were in atrial flutter. The relationships between atrial rhythm, blood flow pattern and the presence/absence of spontaneous echocardiographic contrast or thrombus within the appendage were investigated. Transesophageal echocardiography allowed recording of blood flow velocities in 81 of the 84 patients studied. In 51 of the 55 patients in sinus rhythm the pulsed Doppler study showed a biphasic blood flow pattern, whereas a multiphasic pattern was found in the two patients with atrial flutter and in 14 patients with atrial fibrillation. In four patients with sinus rhythm and 10 patients with atrial fibrillation, no significant blood flow velocity could be detected. Thrombus or spontaneous echocardiographic contrast were found within the left atrial appendage in 20 patients, and in all these patients blood flow was either absent or significantly reduced. Our findings indicate that an absent or low blood flow velocity within the left atrial appendage represents a predisposing factor for thrombosis. Isolated left atrial appendage dysfunction has been documented in four patients during sinus rhythm, which may lead to thrombosis. This observation may offer an explanation for cardioembolic events that occur occasionally in patients without apparent heart disease and sinus rhythm.

Scopolamine improves autonomic balance in advanced congestive heart failure.

BackgroundSympathetic hyperactivity and parasympathetic withdrawal in patients with congestive heart failure correlate closely with disease severity and overall survival. The modulating effects of drugs on the autonomic dysfunction may contribute to improve survival. Low-dose scopolamine has a vagomimetic effect in normal subjects and patients after acute myocardial infarction. We assessed whether transdermal scopolamine would increase vagal activity in patients with congestive heart failure. Methods and ResultsHeart rate variability was assessed at baseline, 24 hours after one patch of transdermal scopolamine, and 48 hours after scopolamine withdrawal in 21 patients with moderate to severe heart failure. Scopolamine increased both time- and frequency-domain parameters of heart rate variability. Specifically, the mean RR interval and its SD increased by 5.5% (P<.001) and 45% (P<.001), respectively. The change remained significant when corrected for mean heart rate with a 39% (P<.01) increase of the coefficient of variation. The absolute power of the high-frequency component was also significantly augmented. All the parameters returned to base-line after scopolamine withdrawal. Individual analysis showed that in the 7 patients in whom scopolamine did not increase mean RR interval, heart rate variability did not change. ConclusionsTransdermal scopolamine increases vagal activity as assessed by heart rate variability in patients with congestive heart failure. This autonomic modulation does not occur in all patients and can be predicted by RR interval changes. Whether such restoration of the autonomic balance might have beneficial effects in the long-term management of patients with congestive heart failure remains to be determined.

Interaction Between Exercise Training and Ejection Fraction in Predicting Prognosis After a First Myocardial Infarction

BACKGROUNDnAlthough recent meta-analysis trials have shown that exercise training may improve survival after myocardial infarction, the mechanism of this beneficial effect is still unknown. The purpose of this study was to detect possible interactions between exercise training and predictors of prognosis after a first myocardial infarction.nnnMETHODS AND RESULTSnPatients with uneventful clinical courses after a first myocardial infarction were randomly assigned to a 4-week training period (125 patients, group 1) or to a control group (131 patients, group 2). Before randomization, all patients underwent a symptom-limited exercise test (28 +/- 2 days after myocardial infarction), 24-hour Holter monitoring, and coronary arteriography (31 +/- 3 days after the acute episode). After a mean follow-up period of 34.5 months, 18 patients had cardiac deaths (5 in group 1 and 13 in group 2). Multivariate analysis by Cox regression model showed that ejection fraction was the only independent prognostic indicator (P = .03). Evidence existed of an interaction between ejection fraction and exercise training, showing an effect of physical training on survival that depended on the patients ejection fraction. Among patients with ejection fractions < 41%, the relative risk for an untrained patient was 8.63 times higher than for a trained patient (P = .04), whereas for ejection fractions > 40%, the estimated risks for trained and untrained patients were similar.nnnCONCLUSIONSnThese data show that exercise training may prolong survival in post-myocardial infarction patients with depressed left ventricular function. A randomized trial in such patients seems warranted.

Incidence and Prognostic Significance of Symptomatic and Asymptomatic Exercise-Induced Ischemia in Patients with Recent Myocardial Infarction

To determine the incidence and the significance of anginal chest pain during abnormal exercise testing (S-T greater than or equal to 0.1 mV) in patients with recent myocardial infarction we reviewed a series of 353 patients who underwent maximal bicycle exercise stress 4-8 weeks following acute myocardial infarction. Of the 353 patients, 26 had ischemic ECG changes and chest pain (group A); 85 patients had ischemic ECG changes but no chest pain (group B). The two groups differ significantly only in the frequency of a history of typical angina pectoris more than 6 months prior to acute myocardial infarction (group A 42.3% vs. group B 15.2%, p less than 0.01). Typical chest pain is more frequent in anterior versus inferior myocardial infarction (50 vs. 14.4%, p less than 0.001). The patients were followed up for 28.8 +/- 8.7 months with clinical and exercise testing controls. The incidence of exertional angina during the follow-up was significantly more frequent in group A patients than in group B patients (80.7 vs. 24.7%, p less than 0.001). Unstable angina pectoris was more frequent in group A (34.6 vs. 11.8%, p less than 0.01). There was no statistically significant difference in mortality (group A 3.8% vs. group B 5.9%) and cardiac events (group A 3.8% vs. group B 5.9%) between the two groups. Thus, we concluded that the occurrence of anginal pain associated with S-T segment depression during exercise testing does not increase the prognostic risk.

Exercise Testing after Nontransmural Myocardial Infarction

In order to ascertain the prognostic value of exercise testing in patients suffering nontransmural myocardial infarction, 74 patients performed a bicycle-ergometric test 4 weeks after the onset of the

Relationships between Anaerobic Threshold and Exercise Hemodynamic Pattern in Patients with Previous Myocardial Infarction

UNLABELLEDnIn 78 male class I and II NYHA patients with previous myocardial infarction, the relationships between ventilatory anaerobic threshold levels and hemodynamic patterns during a maximal symptom-limited stress test in the supine position were studied. Among the 36 patients with abnormal exercise wedge values, 11 showed an anaerobic threshold (AT) less than 35% of the maximal predicted VO2(mpVO2) (group A) and 23 showed an AT of 36-50% mpVO2 (group B). In 2 patients, the AT was greater than 50% mpVO2. Among the 42 patients with normal exercise wedge pressure, 13 showed an AT of 36-50% mpVO2 (group C), whereas in 29 patients, the AT was greater than 50% mpVO2 (group D). The mean value of AT in group A was significantly lower than in group B (8.6 +/- 0.7 vs. 11.7 +/- 0.5 ml/kg.min; p less than 0.05). No difference was found in the mean of the AT between groups B and C, while the mean value of AT in group D was significantly higher than in group C (16.9 +/- 0.4 vs. 12.9 +/- 0.6 ml/kg.min; p less than 0.005). No significant differences between groups C and D were found in the invasive and noninvasive parameters considered. Groups C and D were statistically different from groups A and B for pulmonary capillary pressures, total pulmonary resistances, stroke indexes, heart rates, arteriovenous O2 differences, total systemic resistances and lactate concentrations. Total pulmonary resistances and heart rates were statistically higher and stroke indexes were statistically lower in group A than in group B.nnnIN CONCLUSIONn(1) patients with normal exercise wedge values show a higher AT than patients with abnormal exercise wedge values. (2) Patients with normal exercise hemodynamic patterns classified according to their AT show no difference in hemodynamics; in these patients the level of AT seems to be related to peripheral determinants. (3) Patients with abnormal exercise hemodynamic patterns classified according to their AT level show different hemodynamics and different responses in ventricular function; in these patients the level of AT seems to be related to the cardiac impairment.

Short-term reproducibility of ergometric parameters in functional stress test after recent myocardial infarction

In order to assess the short-term reproducibility of the most important ergometric parameters, 108 males (mean age 50.3 +/- 7.8 years) underwent a functional stress test (FST) on average 35 days after myocardial infarction. The exercise test was repeated 3 days later in the same conditions. Patients were fasting and in pharmacological washout. The following parameters were analyzed: total work performed (TWP), VO2, heart rate (HR), systolic blood pressure (SBP), arrhythmias and S-T segment depression and elevation. TWP and VO2 values did not show any significant difference during the two tests under the various workloads. HR and SBP responses proved to be well reproducible in patients with HR and SBP not exceeding the mean values obtained from 222 normal subjects who underwent the same exercise test by more than +/- 1 SD; reproducibility was significantly lower in the other patients, particularly in patients with HR and SBP exceeding normal values by more than +/- 1 SD. Therefore, in this case, further FST are necessary to obtain more reliable parameters to decide on individual pharmacological and exercise prescriptions. Arrhythmias were reproducible up to 67% (p less than 0.01) regardless of Lowns class and the presence of S-T segment depression or elevation. S-T segment depression or elevation was reproducible up to 100%.

Beurteilung von Gallopamil (D 600) bei Patienten mit chronisch stabiler Angina pectoris —, Ergebnisse einer plazebokontrollierten Einfachblindstudie

Die antianginosen Effekte von Kalziumantagonisten beruhen auf verschiedenen Wirkmechanismen, die entweder in einer Verringerung des myokardialen Sauerstoffverbrauchs und/ oder einer Verbesserung der Sauerstoffzufuhr zum Myokard bestehen, je nach Affinitat fur spezifische Wirkorte und Unterschieden in der Pathogenese der Myokardischamie.

Assessment of gallopamil (D 600) in patients with chronic stable angina pectoris Results of a placebo-controlled single-blind study

The anti-anginal effects of calcium antagonists are due to a reduction of myocardial oxygen uptake and/or an improvement of oxygen supply to the myocardium, depending on the affinity of the drug to specific sites of action and differences in the pathogenesis of the myocardial ischaemia.