New studies have shown that, although defibrillators complete their task of delivering a shock to restart a failing heart, patients are about six times more likely to die after they receive their first life-saving shock.

No less than 30 percent of the patients who receive the lucky jolt experience heart failure within a day. While for some the defibrillator actually works, for others it only announces the inevitable.

There is also the issue of appropriate and inappropriate shocks, the first one increasing risks of subsequent death more than fivefold and the second one making a patient 3 times more in danger.

In a study of 829 heart-failure patients with implanted defibrillators, researchers found that 269 received at least one shock over a period of 45.5 months. Of these, 128 got shocks that were medically warranted, 87 got "inappropriate" shocks, and 54 received both kinds.

"The important message is that the first occurrence of shocks is not a random event in an otherwise stable clinical course but a sign of clinical deterioration in the underlying disease process," says Dr. Jeff Healey and Stuart Connolly of McMaster University in Hamilton, Ontario, as quoted by Reuters.

The conclusion here is that defibrillators are not only a life-saving device that should be taken for granted, but also a medical instrument that triggers an alarm whenever the patient is in danger, something that patients and doctors as well should put their hearts into.