Exercise as it relates to Disease/The Effects of Exercise in Patients with ICD's

This is a critique on a journal article about the effects of exercise in patients with an implantable cardioverter defibrillator (ICD). This critique has been written as part of a University assignment for the unit Health, Disease and Exercise.

The journal article: Luc Vanhees, Marion Kornaat, Johan Defoor, Geert Aufdemkampe, Dirk Schepers, An Stevens, Henk van Exel, Jeroen van den Beld, Hein Heidbüchel, Robert Fagard. Effect of exercise training in patients with an implantable cardioverter defibrillator. European Heart Journal. 2004; 25(13): p. 1120-1126.

What is the background to this research?
ICD stands for Implantable Cardioverter Defibrillator, which is a device that is surgically positioned on the left side of the chest near the heart or in the abdomen. ICD's are used in patients who develop arrhythmias, which are irregular heartbeats. When a patient with an ICD goes into arrhythmia, this small device uses electrical shocks to regulate and control the beating of the heart back to normal sinus rhythm.
 * What is an ICD?

Patients with ventricular arrhythmias of the heart have been treated with implantable cardioverter defibrillators for quite some time now, since 1994. Although these small implantable devices decrease the risk of sudden cardiac death, there is a great deal of apprehension and worry within todays society of ICD's providing patients with the incorrect shock release during physical activity and whether exercise training is safe to do with an ICD.

There is an insufficient amount of research that is present in regards to whether or not exercise training is safe for patients with an ICD. However of the few studies that have been done, there is evidence that exercise training is completely safe for ICD patients and it is not linked to an increased likelihood of being falsely shocked by the device.

The aim of this study was to determine the effects of physical activity in patients with an ICD compared to other cardiac patients without an ICD. It also looked at whether exercise training in ICD patients is linked to an increased risk of being inappropriately shocked.

Where is the research from?
All of the patients in the case group with an ICD were either part of the ambulatory cardiac rehabilitation program at the Department of Cardiovascular and Respiratory Rehabilitation of the Rijnlands Rehabilitation Centre in Leiden, The Netherlands, or from the Cardiovascular Rehabilitation Unit of the University Hospitals of Leuven, Belgium. All of the patients in the control group were patients with a cardiac disease from the University Hospitals in Leuven, Belgium.

The Ethics Committee of the Faculty of Medicine accepted informed consent documents from the patients prior to exercise.

The article being critiqued was written by Luc Vanhees who has a succeeding reputation within the exercise physiology field. He initially started his career as an exercise physiologist at the Catholic University in Leuven, then became a physical therapist in cardiopulmonary rehabilitation at the University Hospitals of Leuven. Currently he is a member of the board for the European Association of Cardiovascular Prevention and Rehabilitation and as part of his role he reviews many international medical journal articles.

What kind of research was this?
This journal article was a case control study, which is a type of study that gives a comparison of patients with a disease (case) and patients without the disease (control) and then determines the link between the risk factor and the particular disease.

Advantages:
 * Gives an immediate look at numerous risk factors
 * Examines uncommon diseases
 * Typically less time taken to carry out the experiment

Disadvantages:
 * Sometimes hard to obtain an appropriate control group
 * Retrospective, so they depend on memory (recall bias)

What did the research involve?
The research involved 92 patients with an ICD and 473 cardiac patients without an ICD. Two ambulatory exercise training programs in two different places, Leiden and Leuven, were set up for the patients to complete. Before and after this training program, a maximal cycle-spiroergometric exercise test was completed until the patients reached exhaustion. Additionally, these ambulatory training programs were offered to all patients 3 times a week for 3 months consisting of 90 minutes.

There were a few limitations to this study including the fact that some of the ICD patients stopped participating in the study leading to a limited sample size, very little research is available for this topic showing that the demand for larger studies is highly required, and the study is about 12 years old indicating that newer research should be carried out to determine any significant changes since the previous studies. This research however highly suggests that it is safe for patients with an ICD to participate in physical activity programs as it gives promising results, and they should not have any fear of receiving inappropriate shocks from the device.

What were the basic results?
The results indicated that most of the participants completed this study with only a few dropping out. From the remaining patients, exercise was stopped due to exhaustion.

Interestingly, there were no significant differences in blood pressure and heart rate during rest and sub maximal exercise between ICD patients and the control patients at baseline exercise. However, during baseline peak exercise, heart rate was considerably lower in ICD patients compared to the control group. Additionally, peak VO2 along with peak oxygen pulse were much lower in ICD patients.
 * Baseline Exercise:

There was an increase in heart rate, VO2 and oxygen pulse during peak exercise in both the ICD and control patients. Although there was an increase, the ICD patients VO2 and oxygen pulse at peak exercise remained much lower than the control patients, suggesting that ICD patients made much smaller improvements in aerobic power.
 * After Exercise Training:

During and in between exercise testing, there were numerous appropriate shocks delivered to patients. Furthermore, there was only one inappropriate shock delivered to a patient.

The data that was collected was analysed by the Sas Institute Inc, Cary, NC, USA by using the SAS statistical software 8.0 for windows.

What conclusions can we take from this research?
Although this article is quite strong, it is not without some faults. The results from this research show that the effects of exercise are fairly lower when compared to the control group indicating that the research could have studied not only the physical aspect of health, but the psychological as well. In addition, the population groups within this research were from two different training programs, one from Leiden and the other from Leuven. These two training programs were comparable as they both consisted of similar activities, however to get more accurate results, the research could have set up just one type of training program rather than two.

There are few studies that have investigated the effects of exercise in ICD patients, indicating that more comprehensive research should be carried out so that more evidence is provided for these patients. This may give patients more courage to participate in physical activity without any fear.

Practical Advice
This research is extremely important in the real world, as cardiovascular disease was the underlying cause of 21, 513 deaths in Australia during 2011. Furthermore, sudden cardiac death is responsible for about 50% of all cardiovascular deaths worldwide which is primarily caused by ventricular arrhythmias.

Although a few articles provide evidence that exercise is safe for ICD patients and should not be ruled out of their everyday life, it is still unclear and up for debate if exercise has an effect on the psychological aspects of health including depression, anxiety and quality of life.

ICD patients who are concerned about the safeness of exercising should contact their cardiologist.

Further Information/Resources
For further information on the effects of exercise training on patients with an ICD and whether or not exercise is safe for these patients read below; additionally contact a cardiologist for further information. http://electrophysiology.onlinejacc.org/article.aspx?articleid=2552065
 * Safety and Efficacy of Exercise Training in Patients With an Implantable Cardioverter-Defibrillator:

http://heartfailure.onlinejacc.org/article.aspx?articleid=1671244
 * Exercise Training and Implantable Cardioverter-Defibrillator Shocks in Patients With Heart Failure:

http://eurheartj.oxfordjournals.org/content/35/44/3097 http://www.heartrhythmcharity.org.uk/Documents/Booklets/Physical_activity_for_ICD.pdf
 * Exercise and competitive sports in patients with an implantable cardioverter-defibrillator:
 * Physical activity and exercise advice for patients with an ICD: