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Consultant cardiologist Dr Antonis Pantazis describes why survival rates are markedly better in dilated cardiomyopathy
Dilated cardiomyopathy (DCM) is a descriptive term and a diagnosis which characterises enlarged hearts with reduced pumping function. The condition can be inherited and it is likely that the familial element in its presentation is under-recognised. The study of families with DCM has helped identify early cases with no or subtle symptoms and to reveal the broader spectrum of the clinical presentation.
A great variety of causes should be considered when investigating familial but also sporadic (isolated) dilated cardiomyopathy. The causes may differ with age. Early clinical observations about this condition were disappointing. The prognosis appeared to be worse than for a number of cancers with most of the patients expected to die within five years. And one third of patients were thought to deteriorate after diagnosis where another third of them would not improve. The data, however, reflected the era before new strategies for the management of this condition were implemented. The situation started changing three decades ago. New medications and interventions have been tested in studies and proven to be very helpful, not just for the symptomatic improvement but also for the overall prognosis.
Increased awareness of the condition in recent years and recognition of subtle symptoms has helped early diagnosis and therefore early management. Without doubt, this can change the outcome of the condition and help to prevent complications. With the knowledge that the disease can be inherited, family screening has also contributed a great deal to early diagnosis. With knowledge of an existing or potential problem, lifestyle modifications and medication can be applied on time. Young people can be given appropriate advice when undergoing preventative screening and this is much better than treating an already severe condition.
Understanding of the condition
Understanding about the mechanisms and progression of heart dysfunction has significantly increased in the last few years. Studies have shown a number of mechanisms are activated when the heart function starts to go down and doctors are now trying to use these mechanisms in a beneficial way for the patient. In the context of a weak heart, the body’s reaction triggers compensatory mechanisms that can be helpful short term but damaging in the long term. Although it was previously thought that a weak heart needs medication that will make it beat more strongly, contemporary cardiology has been able to apply treatment that interferes with the more basic mechanisms.
An example of this is medication that prevents the heart condition from deteriorating further by keeping the heart rate and function mildly suppressed and under reasonable control. This is because studies have shown that the more you activate the failing heart, the worse it becomes in the long run. Whereas the more you protect the heart from its own compensatory reaction, the safer it is for the heart in the long term. So the philosophy in the management of heart dysfunction has changed over the years and is focusing on the prognosis and prevention of complications alongside the immediate reduction of symptoms.
To investigate the efficacy of this type of medication, studies have been conducted. Participating patients have been separated into two groups—those who would receive active medication and those who would only receive placebos (inactive substances). Some of the studies were interrupted early because the benefit of the medication and the improvement in survival and other parameters was so obvious that it was unethical to not treat both groups with the medication. These medications include the betablockers, ACE inhibitors, angiotensin receptor blockers (ARB), and spironolactone or eplerenone. Their use has introduced a new era in the clinical course of cardiomyopathy. Doctors are strongly encouraged to take advantage of these drugs. In some cases, treatments that prevent blood clots are also important to keep the patient safe and free of complications.
Another revolution rather than evolution in the management of heart dysfunction associated with DCM is the use of implantable devices that intervene in the heart’s electrical system. In some DCM patients the heart’s electrical impulse is interrupted or delayed. Then pacemakers can replace the natural conduction system of the heart. Initially pacemakers were only used to safeguard the uninterrupted heart rhythm but since then it has been found that a number of people with DCM have irregular and out of synchronisation contraction of the heart muscle. There are pacemakers available now that can deliver the electrical activation to both sides of the heart simultaneously (biventricular pacing) and coordinate contraction better. This can help improve the symptoms in a number of patients. It is likely that this has had a positive impact on survival too.
Some patients with DCM, especially when heart function is severely impaired, may suffer lethal arrhythmia in the form of a very fast heart beat. These days this can be predicted in most cases and prevented with internal defibrillators (ICDs) that monitor the heart rhythm constantly and deliver a shock when a life threatening arrhythmia is not self terminated. It is obvious that these devices save lives and have greatly changed survival in DCM. ICDs that can be biventricular pacing systems at the same time are probably an excellent combination in those patients who need them. Studies show that this option is also improving survival.
If everything else fails there is the option of a heart transplant. In some cases, patients need immediate heart function support until a new heart becomes available. In those cases, assist devices can be implanted. These are small pumps that take over the left ventricular pumping function of the heart. Sometimes they take over the function of both sides of the heart. These devices are being used on patients waiting for a transplant and unlikely to survive if they do not get one quickly. Although the assist devices and transplanted hearts have a number of complications and a limited time-span, they can now be in place for longer periods of time and are being improved continuously.
Last but not least, research in the field of stem cells shows encouraging results. Such a treatment and the combination of all other options that are available these days might help the clinical course of DCM.
Today DCM is recognised and treated very differently than in the years when the prognosis was thought to be very unfavourable. The target should be that all patients or potential patients take advantage of the advances. It would be fortunate if patients were recognised early, could benefit to the maximum from all available options indicated in their cases and that relatives of DCM patients received regular screening for the condition.