Evaluation of a new treadmill exercise protocol to unmask type 1 Brugada electrocardiographic pattern: can we improve diagnostic yield?

AIMS: High precordial leads (HPL) on the resting electrocardiogram (ECG) are widely used to improve diagnostic detection of type 1 Brugada ECG pattern (Br1ECGp). A parasympathetic activation marks the initial recovery phase of treadmill stress testing (TET), and this can be useful for detecting the typical ECG pattern. Our study aimed to evaluate the role of a new HPL-treadmill exercise testing (TET) protocol in detecting Br1ECGp fluctuation compared to resting HPL-ECG. METHODS AND RESULTS: 74 out of 163 patients of a Brugada syndrome (BrS) Brazilian cohort (GenBra Registry) underwent exercise testing with HPL-TET protocol. Precordial leads were displayed in strategic positions in the right and left parasternal spaces. The step-by-step analysis included ECG classification (as presence or absence of Br1ECGp) in standard vs. HPL leads placement in the following sequences: resting phase, maximal exercise, and the passive recovery phase (including 'quick lay down'). For heart rate recovery (HRR) measurements and comparisons, a Student's t-test was applied. McNemar tests compared the detection of Br1ECGp. The significance level was defined as P < 0.05. Fifty-seven patients (57/74; 77%) were male, the mean age was 49.0 ± 14, 78.4% had spontaneous BrS, and the mean Shanghai score was 4.5. The HPL-TET protocol increased Br1ECGp detection by 32.4% against resting HPL-ECG (52.7% vs. 20.3%, P = 0.001) alone. CONCLUSION: Stress testing using HPL with the passive recovery phase in the supine position offers an opportunity to unmask the type 1 Br1ECGp, which could increase the diagnostic yield in this population.

Valor do teste de esforço computadorizado no diagnóstico diferencial entre fenômenos isquêmicos de origem obstrutiva e näo-obstrutiva / Value of Computadorized Exercise Stress Test in the Differentiation Among Ischemic Phenomena of Obstructive and Non-obstructive Origin

PURPOSE--To describe groups of patients who have obstructive and non-obstructive coronary artery disease, through computadorized exercise stress test. METHODS--The test was done in 121 patients, all male, divided into 3 groups: GN group, 50 patients with normal electrocardiographic response to exercise; GLO group, 40 patients with obstructive coronary artery disease and GNO group, 31 patients with normal coronary arteries, showing one or more of the following entities: intramural coronary traject, coronary tortuosity, slow flow, mitral valve prolapse or left ventricular hypertrophy. GLO and GNO groups presented with abnormal response of the ST segment during exercise. The quantitative variables registered by computer were particularly analyzed as follows: STL (point Y depression), slope, index and ST segment integral. The magnitude of ST vector was visually measured and quantified. The statistic study was made through ANOVA and multiples comparison by the Scheffe's method, Fisher's test, quisquare and sensibility, specificity and accuracy calculation. RESULTS--There was a significant statistic difference among the 3 groups relative to slope and index (p < 0.05). The integral variable of ST segment did not allow us to differentiate the GLO and GNO groups. In the association study between the ST vector magnitude and abnormal T loop, there was an increase in sensibility of 15//in the exercise stress test. CONCLUSION--The ST segment slope below zero values, define patients having obstructive disease, and the opposite, non-obstructive disease. Values of ST segment index lower than -2 are linked to obstructive disease and higher than -2 linked to non-obstructive. Values of ST segment lower than -7 microV. s separate individuals with normal exercise stress test from those with ischemic type response. The magnitude of ST vector equal to or lower than 0.20mV define normal vectorcardiographic response to the exercise