By Jane Ehrhardt
“There are patients with angina who are told they have a 100-percent blockage in a coronary artery and that nothing can be done about it. But, in fact, things can be done,” says Matthew Sample, MD, interventional cardiologist with Cardiovascular Associates in Birmingham.
Advances in interventional cardiology have produced multiple solutions for inserting stents in patients with chronic total occlusion (CTO). “In the early days, we didn’t have the skill-set or the appropriate equipment to handle 100-percent blockages,” Sample says. “Now we’ve advanced our abilities to the point where we know how to deal with these lesions better.”
Specialty coronary wires have been developed, such as micro catheters that are less than a millimeter in diameter, which help the coronary wires be more aggressive. “Typically a coronary wire has about a gram of tip load pushability,” Sample says. “But if you reinforce that wire by putting a catheter over it all the way to the tip, you dramatically increase the tip load and can push through more challenging lesions.”
Some wires offer greater torque ability, allowing the operator to turn the wire a quarter turn outside the catheter translating to a true quarter turn inside the coronary, which older wires could not do. Other wires come polymer-jacketed to increase or decrease friction. A thinner, stronger, stiffer and more responsive array of wires and sheaths has led to more options for treating CTO.
“Traditionally, in terms of a routine stent, we’d antegrade down the artery from the beginning to end,” Sample says. “But we have techniques now that allow us to go retrograde to the artery through the opposite coronary artery and use collateral branches to get wires into the distal end of the artery.”
For example, if a blockage in the mid-right coronary artery could not be reached antegrade, the operator can go in through the left anterior descending artery and use small connecting collateral branches to reach the right coronary and go backwards through that vessel to increase the likelihood of success.
The algorithms that determine the potential for routes have also grown more sophisticated. The algorithms are like a flow chart, mapping out the optimal option in a “if this, then do that” fashion based on variables for that patient. Factors can include the length of the blockage, the amount of calcium, the area of the total occlusion, and whether it involves side branches. That generates a difficulty score, called a J-CTO score.
Based on the score, the physician can determine how best to start the procedure to open the occlusion. The four options include using either the antegrade or retrograde approach of wire escalation or dissection reentry, in which it purposely enters the subintimal space to get past the blockage and reenter beyond it, then using a stent to connect true lumen to true lumen.
The algorithm also presents hard stopping points for when an operator should switch strategies. “These lesions used to fail opening because we would get stuck trying one strategy over and over,” Sample says. “But now we have better algorithms informing us when to give up on a strategy and adopt a new one. That keeps the procedure moving much quicker and provides better results.”
Not every patient with chronic total occlusion (CTO) qualifies for the procedure. “This is for patients with uncontrolled symptoms despite good medical therapy,” Sample says. “If patients with total occlusion don’t have symptoms like angina or shortness of breath day to day and they get around fine, they absolutely do not need that artery opened because the risks exceed the benefits.”
The risks run about five percent versus one percent for a standard stent procedure. “That’s pretty high in my occupation,” Sample says. “But if the patients understand the risks and what they stand to gain from it, it’s perfectly reasonable to move forward.”
Sample makes it clear to patients that the procedure is about relieving their life-limiting symptoms. Opening the vessels does not prolong life or prevent heart attacks. “We can do help patients who can’t enjoy their day-to-day lives because they’re limited by angina,” he says.
Most importantly, CTO patients need to know there is something that can be done. “If a patient had 90-percent blockage and was having angina, you’d probably recommend getting stented. The 100-percent blockage is no different,” Sample says. “Times have changed. If it’s indicated for the 95-percent blockage, it’s indicated for the 100-percent.”
