Usefulness and safety of shortened head-up tilt testing potentiated with sublingual glyceryl trinitrate in older patients with recurrent unexplained syncope

OBJECTIVES: To evaluate the sensitivity and tolerability of shortened, glyceryl trinitrate (GTN)-potentiated, head-up tilt test (HUT) in patients older and younger than 65 with unexplained syncope and to compare the specificity of GTN-potentiated HUT (GTN-HUT) in older and younger controls. DESIGN: Methodological study. SETTING: Syncope units in secondary and tertiary hospitals. PARTICIPANTS: Three hundred twenty-four consecutive patients with unexplained syncope (100 aged greater than or equal to65 (mean age +/- standard deviation 73 +/- 6; 35 men) and 224 aged <65 (41 +/- 15; 111 men)) and 64 controls (29 aged >= 65 (73 +/- 6; 13 men) and 35 aged <65 (42 +/- 13; 16 men)). INTERVENTION: Patients and controls were tilted upright to 60degrees for 20 minutes. If syncope did not occur, sublingual GTN (400 mug) was administered and 60degrees HUT was continued for 15 minutes. Responses were classified as positive, negative, or exaggerated (slow decrease in blood pressure with a slight decrease in heart rate after GTN). MEASUREMENTS: Electrocardiogram and arterial pressure were monitored continuously. RESULTS: GTN-HUT was positive in 60% and 66% (NS), negative in 29% and 33% (NS), and exaggerated in 11% and 1% (P < .001) of older and younger patients, respectively. In older and younger controls, the GTN-HUT was negative in 70% and 86% and exaggerated in 28% and 9% of cases, respectively, (P < .05). The overall specificity (considering as negative also the exaggerated responses) was 97% in older and 94% in younger subjects. No patient or control experienced serious side effects. CONCLUSION: The shortened GTN-HUT provides satisfactory positivity rate and specificity in older patients. This test may be considered as a diagnostic tool in assessing recurrent unexplained syncope in older patients.