Percutaneous transluminal coronary angioplasty: analysis of unsuccessful procedures as a guide toward improved results

Use of percutaneous transluminal coronary angioplasty: results of a current survey

To evaluate the current use of percutaneous transluminal coronary angioplasty (PTCA) in the treatment of coronary artery disease, 50 operators experienced in angioplasty (mean experience 949 +/- 706 cases) were surveyed. Although the use of angioplasty is still skewed toward less extensive disease (80% of 1-, 64% of 2- and 39% of 3-vessel disease), it is now estimated that 39 +/- 16% of patients undergoing diagnostic angiography are ultimately referred for PTCA, whereas only 28 +/- 13% are referred to bypass surgery. PTCA thus accounts for 58% of revascularization. Although approximately half of current PTCA patients are clinical candidates for bypass surgery, much of the growth of angioplasty has consisted of treating patients who are either too high a risk for bypass, or who have symptoms with medical therapy that are too mild to warrant surgery. Whereas elective procedures for stable angina (60 +/- 18%) are still the predominant indication for PTCA, a substantial fraction of procedures are performed for unstable angina (27 +/- 10%) or for acute myocardial infarction (13 +/- 15%). Despite a 91% current success rate, 9% of cases are unsuccessful, including 3% in which emergency bypass surgery is required. The most common reasons for unsuccessful procedures are failure to cross the lesion with a wire or balloon (52%), failure to dilate the lesion (4%), and abrupt closure of the dilated segment (44%) due predominantly to extensive local dissection. These data, based on a pooled experience of some 46,000 PTCA procedures, offer a unique glimpse into the current expanded application of this technique.

The use of an exchange guide wire in coronary angioplasty

Of 84 consecutive patients referred for coronary angioplasty, an exchange length (260 cm) guide wire was used in 17 (20%) to allow serial passage of different sized dilatation catheters. Exchanges were performed for the following reasons: 1) inability to cross the stenotic segment with a full-sized dilatation catheter, with exchange for a smaller catheter to permit initial dilatation followed by a second exchange to reintroduce the full-sized balloon catheter; 2) premeditated initial use of a low-profile balloon catheter in severe stenosis, with subsequent exchange to a full-sized balloon catheter; 3) inability to achieve a satisfactory reduction of the transstenotic gradient or angiographic stenosis with the initial dilation catheter, requiring subsequent passage of a larger balloon catheter into the partially dilated segment. Eighteen of 19 attempted exchanges and 18 of 19 angioplasty procedures were completed successfully. The use of exchange guide wires permits multiple recrossings of a dilated segment, allows safe serial passage of different sized balloon catheters, and obviates the need for renegotiating difficult proximal coronary anatomy. The exchange guide wire techique can be applied safely and effectively to coronary angioplasty and provides an additional option in the successful completion of movable guide wire angioplasty procedures.

Effect of investigator experience on percutaneous transluminal coronary angioplasty

The NHLBI PTCA Registry collected clinical data on 3,101 PTCA procedures performed at 105 clinical centers between September 1977 and September 1981. To investigate the "learning curve" from introduction through the early application of this new therapy for revascularization, success rates and complication rates were examined by calendar year and according to investigator experience. Success rates improved by calendar year, from 54% in 1979 to 66% in 1981. Investigators with fewer than 50 cases had a success rate of 55%. After an investigator had performed 150 procedures, the success rate was 77%. The increase in success rate was largely the result of a dramatic increase in the ability to cross the narrowing with the catheter, and was accounted for by experience and improved equipment. Patient selection for PTCA was characterized by sex, age, previous CABG, number of diseased coronary arteries and stable Canadian Heart classification over time. Reflecting the increase in the success rate was the decrease in the need to perform elective CABG. Emergency CABG, death and MI rates were low (1% mortality, 5% nonfatal MI) and did not change significantly with time or with investigator experience.