Comparison of diagnostic accuracy of sublingual nitroglycerin test and low-dose isoproterenol test in patients with unexplained syncope

Despite the widespread use of head-up tilt testing as a means for diagnosing vasovagal syncope, standardization of test methodology remains a controversial issue. The aim of this study was to compare the diagnostic value of head-up tilt testing potentiated with sublingual nitroglycerin with that of head-up tilt testing potentiated with low-dose isoproterenol. For this purpose, 71 patients with unexplained syncope (mean age 43 years) and 30 asymptomatic controls were studied. All underwent the sublingual nitroglycerin and low-dose isoproterenol tests on separate days in a randomized fashion. The protocol of the 2 tests was similar and consisted of 2 phases. Initially, subjects were tilted at 60 degrees for 20 minutes without medication; then, if syncope did not occur, patients and controls received sublingual nitroglycerin (300 microg) or low-dose intravenous isoproterenol (mean infusion rate 1.3 +/- 0.5 microg/min) and continued to be tilted at 60 degrees for a further 20 minutes. During the sublingual nitroglycerin test, a positive response (syncope associated with sudden hypotension and bradycardia) occurred in 35 patients (49%), a negative response in 36 (51%), and drug intolerance in none (0%). During the low-dose isoproterenol test, these percentages were 41%, 59%, and 6%, respectively. A concordant response was observed in 53 cases (75%). Among controls, 3 subjects (10%) had a positive response to the sublingual nitroglycerin test and 4 (13%) to the low-dose isoproterenol test. It is concluded that sublingual nitroglycerin and low-dose isoproterenol are equivalent tests for evaluating patients with unexplained syncope. The sublingual nitroglycerin test, however, is simpler, better tolerated, and safer than the low-dose isoproterenol test and, thus, more suitable for routine clinical use.

Isolated noncompaction of the ventricular myocardium. A study in an adult male and literature review

Noncompaction of the ventricular myocardium is a rare congenital disorder characterized by the presence of numerous prominent trabeculations and deep intertrabecular recesses which communicate with the left ventricular cavity. The disease uniformly affects the left ventricle, sometimes also affecting the right ventricle. Noncompaction of the ventricular myocardium is believed to be a disorder of endomyocardial embryogenesis. Familial occurrence has been observed. It may be accompanied by depressed ventricular function, cardiac arrhythmia and systemic embolism. Although noncompaction of the ventricular myocardium is a congenital myocardial disorder, the onset of symptoms is frequently delayed until adulthood. We describe a case of noncompaction of the ventricular myocardium in a 33-year-old male with the typical echocardiographic and cardiac magnetic resonance imaging features of this disease.

Atrial thrombosis in cardiac amyloidosis: diagnostic contribution of transesophageal echocardiography

Few cases of atrial thrombosis detected by transesophageal echocardiography (TEE) in cardiac amyloidosis have been reported recently. We present the cases of 3 consecutive patients affected by AL-type cardiac amyloidosis, symptomatic for heart failure and in sinus rhythm. All patients had a cardiac restrictive pattern at Doppler examination. TEE showed left atrial thrombus in 2 patients and biatrial thrombi in 1 patient; conventional transthoracic echocardiography detected only 1 left atrial thrombus. Our experience confirms the association between cardiac amyloidosis and atrial thrombosis, even in sinus rhythm. TEE should be considered to assess thromboembolic risk in all cases of cardiac amyloidosis with severe diastolic dysfunction.

Atrial thrombi resolution after prolonged anticoagulation in patients with atrial fibrillation

BACKGROUND

Cardioversion of atrial fibrillation in nonanticoagulated patients may be associated with clinical thromboembolism. Prolonged anticoagulation with warfarin before cardioversion of atrial fibrillation produces a marked reduction of cardioversion-related thromboembolism. The benefit of anticoagulant therapy is generally believed to be due to atrial thrombi organization.

PATIENTS AND METHODS

Transesophageal echocardiography (TEE) is highly accurate for diagnosis of atrial thrombi and gives the possibility to serially evaluate the effects of anticoagulant therapy. One hundred twenty-three patients with atrial fibrillation lasting longer than 2 days underwent TEE before cardioversion. An atrial thrombus was identified in 11 patients (9%), and was always confined to the left atrial appendage. TEE was repeated after a median of 4 weeks of oral warfarin. Atrial thrombus had completely resolved in 9 of 11 patients (81.8%; 95% CI, 48.2 to 97.7%); in two patients, clot was still present. No patient had clinical thromboembolism between the two TEE studies.

CONCLUSIONS

In the population of our study, a prolonged course of warfarin therapy was associated with resolution of atrial thrombi in the majority of patients. According to these data, the mechanism of thromboembolism reduction with 4 weeks of anticoagulation before cardioversion in patients with atrial fibrillation seems to be related mainly to thrombus lysis rather than organization. Due to the possibility of thrombus persistence even after prolonged anticoagulation, follow-up with TEE before cardioversion is necessary to document thrombus resolution.