IJCS | Volume 32, Nº4, July/August 2019

369 Mizzaci et al. Cardiopulmonary testing in patients with ICD Int J Cardiovasc Sci. 2019;32(4):368-373 Original Article with ICD. It is equally important in patients with left ventricular dysfunction, for prognostic evaluation, therapeutic control, prescription of physical activity and indication of cardiac transplantation. 6 In patients with ICD, CPET should be preferably performed in a hospital setting. It is essential to be aware of basic parameters and implantable device programming. The physician should be aware of the heart rate zones where ICD therapies are programmed, in order to avoid inappropriate therapies. This type of therapy is harmful to the patient, due to its psychological and clinical implications. 7,8 Literature data demonstrate that symptom-limited exercise testing causes ventricular extrasystole in more than half of patients with coronary artery disease. 9-11 However, 20% of exercise-induced arrhythmias are manifested as paired ventricular extrasystoles or nonsustainedVT. 9 Young et. al., 12 reported complications, such as VT, VF and bradycardia, requiring immediate medical treatment in 24 out of 263 patients (9.1%) at high risk for ventricular arrhythmias during maximal exercise testing. In another study in which 107 exercise tests were evaluated in individuals with ICD, ventricular arrhythmias requiring therapy or death 13 were not observed. Few data are available on the responses and complications associated with CPET in patients with ICD. This study aimed at evaluating the incidence of complications during this test in this population. To do this, the occurrence of ventricular arrhythmias (isolated extrasystoles, paired extrasystoles, ventricular bigeminism and ventricular tachycardia), appropriate therapies, inappropriate therapies, cardiorespiratory arrest during or immediately after exercise, hemodynamic instability, need for hospital admission due to cardiovascular complications and death were observed. Besides, other variables such as metabolic, ventilatory and cardiovascular response, symptoms, duration of exercise achieved and maximal oxygen consumption (VO 2 ) were also reported. Methodology This is a retrospective unicentric observational study conducted between 2007 and 2015, including which male and female patients with ICD for more than three months, for primary or secondary prevention of SCD, who underwent cardiopulmonary exercise testing as recommended by the attending physician. CPET was performed using a calibrated breath by breath gas analyzer, Ultima, Medical Graphic Corporation (MGC), performed according to traditional guidelines. Continuous 12-lead electrocardiographic monitoring and recording system modified by Mason and Likar, Tecnologia Eletrônica Brasileira (TEB), model APEX 2000, was used throughout the test. Measurement of arterial saturation was performed by pulse oximetry (CMS50D) and blood pressure measurement by aneroid sphygmomanometer (Welch Allyn). In addition, latex insulating gloves were used by the medical and technical team throughout the test in order to avoid potential electrical therapies. A magnet was available in the test room in case of inappropriate ICD therapies. The patients were submitted to ICD programming analysis by means of telemetry prior to the CPET. Telemetry was performed using specific equipment related to the manufacturer of the device, in order to obtain detailed programming information, such as VT and VF zones, and the relevant therapies. No therapy was changed or disabled before the test. For each patient, a heart rate cutoff value was determined, basedon individual deviceprogramming. The maximumheart rate established for the protocols applied during exercisewas 10 beats below the first VT zone (VT1) programmed in the ICD. In the VT1 zone, established during ICD programming, usually only the monitoring of electrocardiographic events occurs. In the secondVT or VT2 zone, there are three usual extra-stimulus series and in case of non-reversal, analyzed by the device algorithm, sequential joule discharges are automatically applied. In theVF zone, series of joule discharges are triggered, aiming at arrhythmia interruption. The tests were performed with ramp protocols individually applied according to the estimated functional capacity of each patient, physician’s experience and predicted VO 2 calculated using the Wasserman algorithm. 14 Traditionally, the criteria used are exhaustion, dyspnea, angina or dizziness, pathological abnormalities in blood pressure, sustained ventricular arrhythmia, orthopedic complaints and, in patients with interpretable rest electrocardiogram, ST segment depression greater than 3.0mmor ST segment elevation greater than 1.0mm. All tests would be discontinued if the heart rate reached 10 beats below the programmed VT1 zone as a safety measure intended to avoid inappropriate therapies.