Sunday, October 31, 2010


When I first started private practice, I was given a desk calender by one of the pharmas, which had these sayings " Humans are predetermined to have almost 3 billion heart beats / lifetime. ", and another one which says, " The Galapagos tortoise has a heart rate of 6 beats / minute, and so it should live 177 years ". Does that mean that a reduction in mean daily heart rate be expected to prolong life?
Are these sayings true. I am not so sure. Perhaps a bit exaggerated. Maybe there is some element of truth.
Recently, there were a couple of clinical studies which seem to imply that slowing the heart rate reduces cardiac events. Prime of which are the studies using the drug, Ivabradine. In fact, the good old CASS study of bypass surgery in the good old days, seemed to suggest this.
Well, at the just concluded Canadian Cardiovascular Congress 2010, Dr Sherryn Remihar and colleagues from the McMaster University, Hamilton, Ontario, presented a paper linking CV mortality and morbidity, with increase in basal heart rate. They actually when into the TRANSCEND and ONTARGET data base, of about 30,000 patients. These were patients with stable CAD who were on treatment for hypertension. They were deemed the high risk group. Dr Sherryn and colleagues looked into their baseline heart rate each time they came for follow-up over 56 months, and related it to CV mortality, strokes, MIs, and heart failure admissions. They found that if you suffer from stable CAD, and your baseline heart rate is in excess of 70 /min, you have a40-50 % increase risk of developing one of these CVS complications, namely CV death, strokes, heart attacks and heart failure. That is very significant. You cannot argue with a cohort of 30,000 patients. In fact, the risk starts to go up from a mean baseline heart rate of 50 / min. They observed an increasing trend from a HR of 50/min. Whats important, this trend seemed to be more important for those 65years or younger. It seemed to be less significant for those above 65 years.
These findings are important. Whether increase heart rates in stable CAD means that these patients had more stress, or poorer heart functions, or inadequate medications, is not certain. We also do not know if lowering heart rates artificially with beta-blockers or Ivabradine, will help. Looks like Ivabradine, helped those patients in heart failure, if SHIFT is to be believed, although BEAUTIFUL did not show the same ( both studies by Servier ).
At the end of the day, maybe it is true, that we each are pre-determined to have 2 billion heart beats per lifetime, so we must use it wisely, otherwise, the heart beats may run out and so may we. So treasure each day and each heart beat. We may live longer and better that way.

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