Thromboembolic risk in atrial flutter. The FLASIEC (FLutter Atriale Società Italiana di Ecografia Cardiovascolare) multicentre study

AIMS

Patients with atrial flutter are believed to be at lower risk of thromboembolism than patients with atrial fibrillation. However, the incidence of atrial thrombi and the need for anticoagulation in patients with atrial flutter is not well established.

METHODS AND RESULTS

A prospective observational multicentre study was undertaken to assess the frequency of atrial thrombi and spontaneous echocontrast and the prevalence for aortic complex atherosclerotic lesions in a cohort of unselected patients with atrial flutter. We evaluated 134 patients (102 male, aged 70+/-9 years); exclusion criteria were history of atrial fibrillation, rheumatic mitral valve disease and mitral mechanical prosthesis. The median of atrial flutter duration was 33 days. Twelve patients had been taking warfarin for more than 7 days. One hundred and twenty-four patients (94%) underwent a transoesophageal echocardiogram, which revealed left atrial appendage thrombi in two patients (1.6%) and right atrial thrombi in one patient (1%). At least moderate left atrial echocontrast was found in 16/124 patients (13%). Complex atherosclerotic aortic plaques were detected in 10 patients (8%). Atrial flutter conversion was attempted in 93/134 patients (69%). At the 1-month follow-up, two patients experienced a thromboembolic event following restoration of sinus rhythm.

CONCLUSIONS

Atrial thrombi and echocontrast, and complex aortic atherosclerotic plaques are relatively uncommon in patients with atrial flutter. Post-cardioversion embolism was observed in two patients in our study population.

[Transesophageal echocardiography and risk factors for embolism]

Echocardiography is the main diagnostic tool for thromboembolic risk evaluation in patients with atrial fibrillation (AF). Transthoracic echocardiography (TTE) has low sensitivity and specificity in thrombus detection, especially in left atrium appendage; on the other hand the transesophageal approach (TEE) provides information about thrombi located anywhere. In recent years, large trials on thromboembolic risk in AF have given strong value to echocardiographic risk factors such as left atrial enlargement and left ventricular dysfunction, well detected by TTE. Transesophaged echocardiography can be considered the best technique to study factors even more closely correlated to thromboembolic risk, such as spontaneous echocontrast or left atrium appendage abnormalities both anatomical (enlargement and malformations) or functional (low peak velocity). Preliminary data from new trials, like SPAF III and FASTER, confirm this fact. On the other hand, TEE permits the study of thoracic aorta and atheromasic lesions, which can be considered additional direct (ulcerated plaques) or generic thrombotic risks.

[Presence of patent foramen ovale in different heart diseases: incidence in 211 consecutive patients studied by transesophageal echocardiography]

BACKGROUND

Contrast echocardiography during the decompression phase of the Valsalva manoeuvre in course of transesophageal echo study is the ideal method to identify patent foramen ovale.

METHODS

In order to evaluate the incidence of patent foramen ovale in patients with different cardiac diseases we performed contrast injection in 211 consecutive pts submitted to TEE (Transesophageal Echocardiography) in our laboratory between march 1991 and march 1993.

RESULTS

Fiftythree of 211 pts (25%) presented a patent foramen ovale. The incidence in the different cardiac diseases was as follows: 0% in rheumatic mitral disease, 23% in aortic valve disease, 17% in mitral and/or aortic valve prosthesis, 29% in congenital heart disease other than interatrial septal defect, 44% in mitral valve prolapse and 92% in atrial septal aneurysm.

CONCLUSIONS

This study indicates that patent foramen ovale is a common finding in different cardiac pathologies and frequent in mitral valve prolapse and even more in atrial septal aneurysm. In case of peripheral embolism of likely cardiac origin, the patency of the foramen ovale must be recognized, especially when these two latter cardiac anomalies are identified.

Dose and test for dipyridamole infusion and cardiac imaging early after uncomplicated acute myocardial infarction

To evaluate the relation of the dose of intravenous dipyridamole on results of thallium and echocardiographic testing, the results of standard- (0.56 mg/kg/4 minutes) versus high- (0.84 mg/kg/10 minutes) dose dipyridamole were obtained 9 +/- 3 days after uncomplicated acute myocardial infarction in 57 patients. New wall motion abnormalities were compared with redistribution of thallium imaging and results of discharge coronary angiography. The sensitivity of thallium in predicting the presence of multivessel coronary artery disease was significantly (p < 0.01) higher (85%) than echocardiography (53%) and was unaffected by the dose. However the sensitivity of echocardiography was better with the higher dose (53 vs 14%). Minor adverse effects occurred in 34 patients (59%) after receiving the high dose and only in 4 patients (7%) after the standard dose (p < 0.001). Thus, thallium-201 scintigraphy during standard-dose dipyridamole infusion is more effective than high-dose dipyridamole echocardiographic testing in safely identifying patients who could benefit from early invasive evaluation and therapy.

[Thallium and echo- dipyridamole in the early selection of patients at risk after acute myocardial infarction. Which test? What dose?]

The optimal iv dose of Dipyridamole (Dip) in echocardiography (echo) or Thallium scintigraphy (Tl) remains undetermined. To select the high-risk patients (pts) subset, we performed echo and Tl with standard dose (SD) and high dose (HD) Dip infusion (0.56 mg/Kg/4'-0.84 mg/Kg/10' respectively) in 40 pts 9 +/- 3 days after admission for acute myocardial infarction (AMI). Of these, 38 pts had coronary artery disease at angiography and 2 had no significant lesions. Worsening in regional wall motion on echo and reversible perfusion defects on Tl were considered abnormal patterns. SD had no side effects; only in one pt was ischemic ventricular dysfunction detected on echo, whereas Tl redistribution was found in 24 pts (12 had multivessel disease and 12 had one coronary stenosis greater than or equal to 70%). HD caused adverse reaction in 24 pts, did not enhance SD-Tl sensitivity, but induced abnormal echo in 18/24 pts with transient defects on SD-Tl. Eleven of the 16 Tl negative pts had occlusive disease, 3 had one vessel disease and 2 showed no evidence of coronary artery disease.

IN CONCLUSION

SD is safe but often provokes a submaximal coronary vasodilation. Failure to detect ischemia on echo may be explained by this. SD-Tl is, however, able to identify high-risk pts who may benefit from early myocardial revascularization. HD does not enhance SD-Tl sensitivity, but it is necessary to induce echo abnormalities which are all too often undetectable at SD.

[Myocardial scintigraphy using 201-thallium and 2-dimensional echocardiogram after dipyridamole infusion in the early evaluation of post-infarct residual ischemia]

Dipyridamole thallium scintigraphy (TI-DP) and dipyridamole two-dimensional echocardiography (Echo-DP) were performed on 38 patients (pts), 11 +/- 4 days after acute myocardial infarction. Our study intends to assess whether or not imaging methods are useful both in identifying residual jeopardized myocardium and in selecting pts for coronary angiography. No serious side effects were induced during the DP test. In 11 pts angina was not induced, worsening of wall motion abnormalities was not detected on Echo-DP; no reversible defects were found on TI-DP. The remaining 27 pts who showed transient defects on TI-DP underwent coronary angiography. All pts had either multivessel coronary disease or severe single-vessel disease and myocardial revascularisation was performed in all of them. Of these 27 patients, only 5 suffered angina and showed ST-T depression; only in 15 dyskinetic wall motion development was detected on Echo-DP. Finally we can conclude: the DP-test can be safely performed in the early post-infarction period; both the reported imaging methods enable the identification of jeopardized myocardium even if with different ranges of sensitivity; pts negative to both TI-DP and Echo-DP can be safely followed without coronary angiography; pts with transient defects on TI-DP can be reasonably referred to coronary angiography.