IJCS | Volume 32, Nº4, July/August 2019

370 Table 1 - Baseline characteristics of the study population Variable Value Age (years) 55 ± 10 Gender (%) Male 68.1 Female 31.9 BMI (kg/m 2 ) 25.5 ± 4.8 Diagnosis (%) Ischemic cardiomyopathy 40.6 Dilated cardiomyopathy 56.5 Hypertrophic cardiomyopathy 2.9 Resting ECG (%) Pacemaker rhythm 40.6 Sinus rhythm 15.9 Left bundle branch block 15.9 Right bundle branch block 7.2 Electrically inactive zone 7.2 Atrial fibrillation 2.9 Medication (%) Beta-blockers 94.2 Calcium channel blockers 5.8 ACEI or ARB 87.0 Diuretics 89.9 BMI: body mass index; ECG: electrocardiogram; ACEI: angiotensin- converting enzyme inhibitor; ARB: angiotensin receptor blocker. Mizzaci et al. Cardiopulmonary testing in patients with ICD Int J Cardiovasc Sci. 2019;32(4):368-373 Original Article Data analysis was performed by IBM SPSS software version 19 and Microsoft Office Excel 365 was used for data tabulation. The quantitative variableswere presented bymean and standard deviation and qualitative variables by absolute frequency and percentage, then descriptive analysis of the data was performed. A 95% confidence interval (95% CI) was calculated using the binomial test. To test whether the frequency of serious events was smaller than 10%, exact binomial test was used. Results In this study, 69 patients with ICD were included. Table 1 shows the characteristics of the study population.  Exercise time was 8.7 ± 2.3 minutes, with peak VO 2 of 13.3 ± 4.3 ml.kg - 1 .min -1 . The heart rate reached at the peak of exercise was 105.9 ± 22.9 beats per minute (bpm), corresponding to 62.9 ± 13.4% of the upper limit for the predicted age. All tests were discontinued due to patient exhaustion. Mean final speed was 3.9 ± 0.9 km/h, while mean final inclination was 11.2 ± 3.1% in this protocol. The other CPET variables are presented in Table 2. The heart rate programmed for the VT1 zone in the ICD was 150 ± 9.1 bpm on average. During exercise, the patients achieved 71.8% of the heart rate programmed in the VT1 zone, 61.7% in the VT2 zone and 53.4% in the VF zone. Chart 1 shows the arrhythmias found in the study. The following were considered as complex arrhythmias: paired ventricular extrasystoles, ventricular bigeminism, ventricular tachycardia. There were no sustained ventricular arrhythmia resulting in ICD therapy or inappropriate therapies. Also, there was no cardiorespiratory arrest, hemodynamic instability during or immediately after exercise or hospital admissions due to cardiovascular complications or death. The frequency of severe events was 0%, 95% CI (0 – 5.2%). Thus, we have that the frequency of serious events will be less than 10%. Discussion CPET is a fundamental test recommendedby consensus for the evaluation of patients with left ventricular dysfunction, both for prognostic characterization and for therapeutic control and assistance in the indication for cardiac transplantation. 15,16 However, there is little information regarding the safety of this test in individuals with ICD. As we know, CDI therapy has become a standard indication in this population, both for primary and secondary prevention. 1,3,4 Therefore, the importance of this study was to check the safety of CPET in this type of population. The major concern in performing CPET in patients with ICD is the risk of complications such as ventricular arrhythmias during exercise, resulting in therapies by the device. 7,17 Another risk inherent in the procedure is that it triggers inappropriate therapies by the implantable electronic device. It is known that unnecessary shocks should be avoided, while rapid appropriate therapy for ventricular tachyarrhythmia should be affordable. Inappropriate ICD therapy is not only traumatic for