Fred Lampropoulos
Analyst · Piper Sandler
Thank you, Brian. Let me start with a brief agenda of what we will cover during our remarks today. I will start with an overview of our revenue performance in the third quarter, including the improving business trends we experienced during the quarter. And the areas of our business have performed well despite the challenging operating environment. I will then provide an update on our operating progress and highlights during the third quarter.
After my opening remarks, Raul will provide you with a more in-depth review of our quarterly financial results and a formal financial guidance we reinstituted in this afternoon's press release as well as a summary of our balance sheet and financial condition. After that, we will then open the call for your questions.
Beginning with a review of our third quarter revenue performance, we reported total revenue growth of 0.4% year-over-year in the third quarter, driven by 1% growth in sales of our cardiovascular products, which was partially offset by a 12% decrease in sales of our endoscopy products compared to the prior year. Total sales on a constant currency basis were essentially flat compared to the third quarter of 2019.
Our revenue results increased almost 12% on a quarter-over-quarter basis, which reflects the overall improvement in business trends that we have experienced in recent months. Importantly, this sequential growth was well above expectations and exceeded the high end of our sequential growth range we discussed on our second quarter conference call. While we believe we remain in the early days of the global recovery, we're encouraged by the improving trends we experienced during the third quarter. Specifically, after a difficult April, where we saw a sales decline of 20% year-over-year, we saw a modest improvement on a days adjusted basis in May, and then significant improvement in the month of June. However, sales still decreased in the low single digits year-over-year.
Our business trends were somewhat choppy throughout the month of July, and we experienced the expected seasonal softness in overall procedure trends during the month of August. Together, our total sales for the first 2 months of the third quarter were down 1% year-over-year.
Now September, however, was a different story. We saw a steady improvement in the sales trends throughout the month, and sales increased in the low single digits year-over-year against a tougher comparison as well.
Now I want to take a minute to dig into the underlying trends we experienced during the third quarter as I think it may be helpful for investors that are gauging the patient recovery in Merit's business. First, clearly we are seeing a notable variation in the patient recovery, depending on what region of the world where we do business, and we are even seeing variation within certain geographic regions. By the way of reminder, roughly 60% of our total revenues come from business in the U.S. and the sales in the U.S. decreased 0.6% year-over-year in the third quarter.
Our U.S. business is roughly 80% direct, with the majority of the remaining U.S. business dedicated to servicing OEM customers. Importantly, the underlying business trends in each of these 2 U.S. businesses were notably different in the third quarter.
Understandably, the recovery from the pandemic has been more rapid in our U.S. direct business, where sales increased 5% year-over-year in quarter 3, fueled in part by the incremental sales contribution from our sample collection and transport kit, the Cultura collection and transport system, which is comprised of a nasopharyngeal swab and a transport vial used to collect specimen, with suspected presence of COVID-19.
Sales of the Cultura system were nearly $10 million in the third quarter, which fueled a 29% growth year-over-year in our U.S. custom procedural solutions business line this quarter, and the 22% increase in worldwide custom procedure solutions sales in quarter 3. Conversely, our OEM business, which has been slower to recover as a result of inventory management as our customers adjust to product demand in response to COVID-19, and sales to U.S. OEM customers decreased 21% year-over-year and decreased 17% worldwide this quarter.
Our other business lines in the U.S., peripheral innovation -- excuse me, intervention and cardiac intervention posted strong improvement in sales trends during the third quarter, but were still down year-over-year. Sales of the PI products in the U.S. were down 1% year-over-year and sales of the CI product lines in the U.S. were down 3% year-over-year in the third quarter.
Turning to a brief review of our sales outside the U.S. Total international sales in the third quarter increased 2% on a reported basis and 0.6% on a constant currency basis. Our 2 largest regions outside the U.S. are APAC and EMEA, representing approximately 50% and 43% of our total international sales, respectively, in the third quarter.
Third quarter total international constant currency growth of 0.6% was driven by a 3% increase year-over-year in APAC sales, a 0.5% decrease year-over-year in EMEA sales and a 4.5% decrease year-over-year in sales to the rest of the world.
All international regions had an impact from COVID-19 and are still recovering. Restrictions and lockdowns are changing constantly across regions, most notably in the European markets, causing some limitations to sales contact and low demand for elective procedures.
Turning to a brief review of our recent operating progress during the third quarter. We continue our efforts to move products to our facilities in Mexico and Texas and are on track with a complete transfer of all 14 product lines.
Our PAC business in Australia will be fully closed by the end of the year, and we are in the process of securing a sub tenant. Our Temecula site has been closed, and production has now moved to our Texas facility. And our R&D efforts are ongoing, and we expect to continue our track record of new product introductions going forward.
Finally, I wanted to provide a brief update on our clinical studies for the WRAPSODY Endovascular Stent Graft. First, we had a productive discussions with the FDA in recent months, and we received IDE approval for the WRAPSODY AV Access Efficacy Study, which we are calling the WAVE study, and IDE approval for a smaller study called the WRAPSODY Central Feasibility Study, which we are calling the Wave Central study. The WAVE study is a prospective, randomized, controlled multi-center study comparing the WRAPSODY Endovascular Stent Graft to percutaneous transluminal angioplasty for treatment of venous outflow circuit stenosis or occlusion in hemodialysis patients. The study will involve 357 patients and will evaluate the safety and efficacy of our stent among other criteria, which are detailed on the study page on clinicaltrials.gov. Start-up activities began in mid-October, and we are currently targeting enrollment for the first patients by the end of the first quarter.
The WAVE Central study is a 25-patient feasibility study to gain additional safety data surrounding the central venous occlusions. This feasibility study will run in parallel with the WAVE IDE study. And after we submit the evidence to the FDA and receive approval, we intend to roll this treatment arm into the Wave IDE. Startup activities are underway for this feasibility study as well, and we are also targeting enrollment for the first patients by the quarter 1 of 2021.
Now with that said, let me turn the time over to Raul, who would like to take you through a detailed review of our financial results and our 2020 financial guidance which we reinstated in this afternoon's press release. Raul?