Application Series 2 Application Series 2
The two principal approaches to dealing with narrowing of the coronary blood vessels are bypass surgery and angioplasty. In bypass surgery, blood vessels from other areas of the body are removed and grafted onto the coronary arteries so that blocked areas are "bypassed". In angioplasty, the narrowings of the coronary arteries, called lesions, are directly opened or widened by balloon inflation, laser beam, rotational ablation or other methods.
"Just in the last year." according to Richard Shaw, Ph D, Director of Research, "the Institute has published a large number of papers that cover the whole gamut of what cardiac intervention does and how it relates to the long-term success of a patient."
One of the Institute's studies, done in the past year, looked at the success and complication rates of balloon angioplasty for different morphologic factors - was the lesion very tight, was it calcified, did contain blood clots, was the lesion located on a bend or straight area of the artery?
"Using our SIR database," said Dr Shaw, "we took 533 consecutive patients representing 1000 lesions that we had treated and conducted a detailed analysis of the different lesion morphologies and groupings within a vessel - a very complicated analysis that I don't think many people could have done in terms of just having that much data available and that much inter-correlation between the lesion characteristics and how they were treated."
"We were able to prove for the first time that the current technology had advanced so far that even in the very severe, very complicated lesion types, the average success rate is now in the low 90%'s and some of our very straightforward lesions have a success rate of 99%. "Two or three other papers we published this year are probably the longest term follow up that's ever been done on patients who have undergone balloon angioplasty. We followed our first 225 patients who were done back in the late 1970's for between 10 and 13 years. We showed the entire treatment history of these people - what kind of events occurred to them over that long history since they had balloon angioplasty - and which ones went on to have coronary bypass surgery. Then we looked at the crossovers between the bypass and angioplasty groups over time."
Ms Chan, who is also the primary SIR database programmer, said that the Institute maintains more than half a dozen databases on its DEC VAX computer. The largest is the angioplasty database with twelve years worth of data on over 5000 patients. The bypass database has data collected since 1985 on over 3000 patients. The catheterisation database, which characterises lesion size and distribution, has over 2000 patients.
"In the bypass database, Ms Chan said, "we look at the procedure itself - what was done to the patient, how many vessels were bypassed, and whether or not bypass surgery was done in combination with other heart procedures such as valve replacements or repairs. Information is collected on the patient's health both prior to and after surgery. Data on the length of hospital stay, days in intensive care, mortality rate, and complicating events are collected in order to identify high risk patients whose health may deteriorate shortly after surgery. By collecting information before and after surgery... we can evaluate how to ensure higher survival rates and to improve the quality of health care for future patients."
Several smaller databases are maintained to provide supporting information both prior to and after procedures are performed, as well.
The data for the databases come from a variety of sources: film of patient's arteries after injection of dye; photographs of the heart muscle after injecting a radioactive material; and data from a treadmill machine.
Patients are "followed-up" approximately one year after angioplasty, bypass and/or other heart surgery. Data are collected through mailed questionnaires which are filled out by the patient. Those patients who fail to respond are then telephoned to obtain the necessary information. Ms Chan said, "We monitor whether patients have had any new events since angioplasty or surgery, such as re-hospitalisation, other cardiovascular procedures, lifestyle changes, changes in the quality of life and any medications the patient may use. Then through written or oral requests we will either send educational pamphlets (eg, how to control blood pressure or how to cook low-fat-meals) or refer the patient to cardiac rehab or our diet and nutrition centres, which will help with long-term patient health care,"
The resultant pool of detailed clinical information would provide reliable information on both procedure outcomes and costs, two crucial factors in today's medical environment. "If you look at what's happening in health care research and reimbursement for health care, people are looking beyond just when a patient is hospitalised and considering the larger, long-term issues. An isolated hospital stay is but a small part of the cost of any procedure or what it does in relationship to productivity and to the long-term survival of patients".
Shaw continues, "our database structures allow us to really look at and reconstruct the patient's history in a very detailed way. we can then do some fairly sophisticated statistical analyses looking at long term outcome and survival of patients undergoing our procedures."
For more information, contact:
Ms Jean Chan, M A
San Francisco Heart Institute
1900 Sullivan Avenue
Daly City, California 94015
USA